Essential oil

{{Short description|Hydrophobic liquid containing volatile aroma compounds from plants}} {{Hatnote group| {{For|the Midnight Oil album|Essential Oils (album)}} {{Distinguish|essential fatty acid|fragrance oils}} }} {{cs1 config|name-list-style=vanc}} {{Vegetable oils|image=SandalwoodEssOil.png|caption=Sandalwood oil}}

'''Essential oils''' are composed of hydrophobic volatile organic compounds, usually in liquid form, obtained from plant material. Essential oils are also known as '''volatile oils''', '''ethereal oils''', '''aetheroleum''', or simply as the oil of the plant from which they were extracted, such as oil of clove. An essential oil is essential in the sense that the oil contains the fragrance or essence of the plant.<ref>{{cite book |chapter= essential oil |title= Oxford English Dictionary |edition= online, American English |chapter-url= http://www.oxforddictionaries.com/us/definition/american_english/essential-oil?q=essential+oil |access-date= 2014-07-21 |archive-url= https://web.archive.org/web/20140809030553/http://www.oxforddictionaries.com/us/definition/american_english/essential-oil?q=essential+oil |archive-date= 2014-08-09 }}</ref><ref>{{Cite journal |last=Mousavi-Sagharchi |first=Seyyed Mohammad Amin |last2=Rami |first2=Mina Rezghi |last3=Hasani |first3=Hanieh |last4=Ghasemi |first4=Maede Mohammad |last5=Farahhal |first5=Maryam |last6=Hasani |first6=Amir Hossein |last7=Seyyedian-Nikjeh |first7=Seyyedeh Fatemeh |last8=Meskini |first8=Maryam |last9=Siadat |first9=Seyed Davar |date=February 2026 |title=Assessment of the efficacy of plant-derived essential oils against Mycobacterium tuberculosis: A systematic review and meta-analysis |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC12830100/ |journal=New Microbes and New Infections |volume=69 |article-number=101699 |doi=10.1016/j.nmni.2026.101699 |issn=2052-2975 |pmc=12830100 |pmid=41583911}}</ref> The term "essential" used here does not indicate that it is nutritionally required in the diet, as with essential amino acid or essential fatty acid.<ref>{{cite journal |pmid=10867060 |year=2000 |last1=Reeds |first1=P. J. |title=Dispensable and indispensable amino acids for humans |journal=The Journal of Nutrition |volume=130 |issue=7 |pages=1835S–40S |doi=10.1093/jn/130.7.1835S |doi-access=free }}</ref>

Essential oils, according to ISO,<ref>{{Cite web |title=European, American and International Standards online |url=https://standards.iteh.ai/catalog/standards/sist/599cef4e-41ea-48e7-8dd1-2039e0ec6fbf/iso-9235-2021 |access-date=2026-02-05 |website=iTeh Standards |language=en}}</ref> are produced either by steam distillation, by mechanical manipulation of the rind of the fruits of the genus ''Citrus'' (also called cold pressing), or by dry distillation. Other methods, such as solvent extraction, are not accepted and, in fact, result in different perfumed products (pommades, concretes, and absolutes). They are used in perfumes, cosmetics, soaps, air fresheners and other products, for flavoring food and drink, and for adding scents to household cleaning products.<ref name="Rana">{{cite journal |last1=Rana |first1=P |last2=Pathania |first2=D |last3=Gaur |first3=P |last4=Patel |first4=SK |last5=Bajpai |first5=M |last6=Singh |first6=NT |last7=Pandey |first7=R |last8=Shukla |first8=SV |last9=Pant |first9=AB |last10=Ray |first10=RS |last11=Dwivedi |first11=A |title=Regulatory frameworks for fragrance safety in cosmetics: a global overview. |journal=Toxicological Research |date=May 2025 |volume=41 |issue=3 |pages=199–220 |doi= 10.1007/s43188-025-00283-2|pmid=40291114 |pmc=12021755 |bibcode= 2025ToxRe..41..199R}}</ref>

Essential oils are often used for aromatherapy. Improper use of essential oils may cause harm including allergic reactions, inflammation and skin irritation. Children may be particularly susceptible to the toxic effects of improper use.<ref name="ReferenceE">{{cite journal |doi=10.3233/JRS-2012-0568 |pmid=22936057 |year=2012 |last1=Posadzki |first1=P |title=Adverse effects of aromatherapy: A systematic review of case reports and case series |journal=The International Journal of Risk & Safety in Medicine |volume=24 |issue=3 |pages=147–61 |last2=Alotaibi |first2=A |last3=Ernst |first3=E }}</ref><ref name="poison.org">{{Cite web|title=Essential oils: Poisonous when misused|url=https://www.poison.org/articles/2014-jun/essential-oils|publisher=US National Capital Poison Center|language=en|access-date=2017-12-01}}</ref> Essential oils can be toxic if ingested or absorbed through the skin.<ref name=poison.org/>

==Production== {{main|Extraction (fragrance)}}

===Distillation=== {{see also|Distillation}} {{unreferenced section|date=November 2022}}

Essential oils such as lavender, peppermint, tea tree oil, patchouli, and eucalyptus are distilled. Raw plant material, consisting of the flowers, leaves, wood, bark, roots, seeds, or peel, is put into an alembic (distillation apparatus) connected to a steam generator (indirect steam distillation) or over water (direct steam distillation). As the water is heated, the steam passes through the plant material, vaporizing the volatile compounds. The vapors flow through a condenser, where they condense back to liquid, which is then collected in the receiving vessel, also called a florentine flask.

The recondensed water is referred to as a hydrosol, hydrolat, herbal distillate, or plant water essence, which may be sold as another fragrant product. Hydrosols include rose water, lavender water, lemon balm, clary sage, and orange blossom water.

The national association for Holistic aromatherapy and medical research published by the NIH report that some essential oils can cause allergic reactions, skin irritation, hormone disruption, and even toxicity if ingested or improperly applied. Poison control centers have documented increase calls related to essential oil exposure, especially in children.

===Expression=== Most citrus peel oils are expressed mechanically or cold-pressed.<ref>{{cite web|title=How Are Essential Oils Extracted?|url=https://naha.org/explore-aromatherapy/about-aromatherapy/how-are-essential-oils-extracted/|last1=Shutes|first1=Jade|website=NAHA – National Association for Holistic Aromatherapy|archive-url=https://web.archive.org/web/20130611075007/https://naha.org/explore-aromatherapy/about-aromatherapy/how-are-essential-oils-extracted/|archive-date=11 June 2013|access-date=16 June 2019}}</ref> Due to the relatively large quantities of oil in citrus peel and low cost to grow and harvest the raw materials, citrus-fruit oils are cheaper than most other essential oils. Lemon or sweet orange oils are obtained as byproducts of the citrus industry.

===Production quantities===

Estimates of total production of essential oils are difficult to obtain. One estimate, compiled from data in 1989, 1990, and 1994 from various sources, gives the following total production, in tonnes, of essential oils for which more than 1,000 tonnes were produced.<ref>{{cite web |url= http://isotc.iso.org/livelink/livelink/971087/ISO_TC_054__Essential_oils_.pdf |title= ISO TC 54 Business Plan – Essential oils | access-date= 2006-09-14}} It is unclear from the source what period of time the quoted figures include.</ref>

:{| class="wikitable" ! Oil !! Tonnes |- | Sweet orange || style="text-align:right;"| 12,000 |- | ''Mentha arvensis'' || style="text-align:right;"| 4,800 |- | Peppermint || style="text-align:right;"| 3,200 |- | Cedarwood || style="text-align:right;"| 2,600 |- | Lemon || style="text-align:right;"| 2,300 |- | ''Eucalyptus globulus'' || style="text-align:right;"| 2,070 |- | ''Litsea cubeba'' || style="text-align:right;"| 2,000 |- | Clove (leaf) || style="text-align:right;"| 2,000 |- | Spearmint || style="text-align:right;"| 1,300 |}

==Uses and cautions== {{More medical citations needed|section|date=September 2010}}

Taken by mouth, many essential oils can be dangerous in high concentrations. Typical effects begin with a burning feeling, followed by salivation.<ref name=Sapeika>{{cite book |last= Sapeika |first= Norman |title= Actions and Uses of Drugs |publisher= A.A. Balkema |year= 1963}}{{page needed|date= October 2014}}</ref> Different essential oils may have drastically different pharmacology. Some act as local anesthetic counterirritants and, thereby, exert an antitussive (cough suppressing) effect.<ref name=Sapeika/><ref name="Turpentine">{{citation|last=Haneke|first=Karen E|title=Turpentine (Turpentine Oil, Wood Turpentine, Sulfate Turpentine, Sulfite Turpentine) [8006-64-2]: Review of Toxicological Literature|date=February 2002|url=http://ntp.niehs.nih.gov/ntp/htdocs/chem_background/exsumpdf/turpentine_508.pdf|archive-url=https://archive.today/20200429004932/https://ntp.niehs.nih.gov/ntp/htdocs/chem_background/exsumpdf/turpentine_508.pdf|archive-date=April 29, 2020|issue=Contract No. N01–ES–65402|publisher=National Institute of Environmental Health Sciences}}{{page needed|date=October 2014}}</ref> Many essential oils, particularly tea tree oil, may cause contact dermatitis.<ref>{{cite journal |doi=10.1097/DER.0b013e31823e202d |pmid=22653070 |title=Tea Tree Oil |journal=Dermatitis |volume=23 |issue=1 |pages=48–9 |year=2012 |last1=Larson |first1=David |last2=Jacob |first2=Sharon E. }}</ref><ref name="ReferenceA">{{cite journal |doi=10.1111/j.1600-0536.2007.01275.x |pmid=18416758 |title=Occupational contact dermatitis due to essential oils |journal=Contact Dermatitis |volume=58 |issue=5 |pages=282–4 |year=2008 |last1=Trattner |first1=Akiva |last2=David |first2=Michael |last3=Lazarov |first3=Aneta |s2cid=10674102 }}</ref><ref name="ReferenceB">{{cite journal |doi=10.1046/j.1440-0960.2002.00598.x |pmid=12121401 |title=Allergic contact dermatitis following exposure to essential oils |journal=Australasian Journal of Dermatology |volume=43 |issue=3 |pages=211–3 |year=2002 |last1=Bleasel |first1=Narelle |last2=Tate |first2=Bruce |last3=Rademaker |first3=Marius |s2cid=46674505 }}</ref><ref name="ReferenceC">{{cite journal |doi=10.1034/j.1600-0536.2000.043001041.x |pmid=10902588 |title=Short Communications |journal=Contact Dermatitis |volume=43 |issue=1 |pages=41–2 |year=2000 |last1=Isaksson |first1=M |last2=Brandão |first2=F. M. |last3=Bruze |first3=M |last4=Goossens |first4=A |s2cid=221576846 }}</ref> Menthol and some others produce a feeling of cold followed by a sense of burning.{{cn|date=April 2026}}

In Australia, essential oils (mainly eucalyptus) have been increasingly causing cases of poisoning, mostly of children. During the years 2014 to 2018, there were 4,412 poisoning incidents reported in New South Wales.<ref name=leeka>{{cite journal |vauthors=Lee KA, Harnett JE, Cairns R|title=Essential oil exposures in Australia: analysis of cases reported to the NSW Poisons Information Centre |journal=Medical Journal of Australia |year=2019 |volume=212 |issue=3 |pages=132–133 |issn=0025-729X |doi=10.5694/mja2.50403 |pmid=31709543 |s2cid=207940224 |doi-access=free }} *{{lay source |template = cite news|url = https://sydney.edu.au/news-opinion/news/2019/12/09/essential-oil-poisoning-calls-on-the-rise-children-most-affected.html||title = Essential oil poisoning calls on the rise, children most affected |date= December 9, 2019 |website= University of Sydney}}</ref>

==Use in aromatherapy== {{main|Aromatherapy}}

thumb|Essential oils can be used in aromatherapy by using essential oil diffusers An overview of systematic reviews found that while aromatherapy has been studied for conditions like anxiety, depression, and pain, the evidence is generally of poor quality and not convincing enough to support its effectiveness.<ref name="lee">{{cite journal |last1=Lee |first1=Myeong Soo |last2=Choi |first2=Jiae Choi |date=2012 |title=Aromatherapy for health care: an overview of systematic reviews |journal=Maturitas |volume=3 |issue=71 |pages=257–260 |doi=10.1016/j.maturitas.2011.12.018 |pmid=22285469}}</ref> Use of essential oils may cause harm including allergic reactions and skin irritation.<ref>{{Cite news |last=Schiffer |first=Jessica |date=March 11, 2021 |title=Essential Oils May Be Wreaking Havoc on Your Skin |url=https://www.nytimes.com/2021/03/11/style/self-care-essential-oils-may-be-wreaking-havoc-on-your-skin.html |work=The New York Times}}</ref> There has been at least one case of death.<ref name="ReferenceE"/>

The effectiveness of aromatherapy has been studied in preliminary research for sleep disorders<ref>{{Cite journal |last1=Ostovar |first1=Mohadeseh |last2=Khademizadeh |first2=Mohammad Hamed |last3=Namjoyan |first3=Foroogh |last4=Kazemi |first4=Asma |last5=Vakili |first5=Sina |last6=Mosavat |first6=Seyed Hamdollah |last7=Mohit |first7=Mohsen |last8=Hashempur |first8=Mohammad Hashem|display-authors=3 |date=2025 |title=A systematic review and meta-analysis of clinical trials on lavender for sleep disorders in older adults |journal=Experimental Gerontology |language=en |volume=211 |article-number=112919 |doi=10.1016/j.exger.2025.112919|doi-access=free |pmid=41057090 }}</ref> and anxiety.<ref>{{Cite journal |last1=Tan |first1=Ling |last2=Liao |first2=Fei-fei |last3=Long |first3=Lin-zi |last4=Ma |first4=Xiao-chang |last5=Peng |first5=Yu-xuan |last6=Lu |first6=Jie-ming |last7=Qu |first7=Hua |last8=Fu |first8=Chang-geng|display-authors=3 |date=2023-06-01 |title=Essential oils for treating anxiety: a systematic review of randomized controlled trials and network meta-analysis |journal=Frontiers in Public Health |volume=11 |article-number=1144404 |doi=10.3389/fpubh.2023.1144404 |issn=2296-2565 |pmc=10267315 |pmid=37325306|doi-access=free |bibcode=2023FrPH...1144404T }}</ref>

== Use as pesticide ==

Research has shown that some essential oils have potential as a natural pesticide. In case studies, certain oils have been shown to have a variety of deterring effects on pests, specifically insects and select arthropods.<ref name=":0">{{Cite journal|date=2010-01-01|title=Repellent activity of essential oils: A review|journal=Bioresource Technology|language=en|volume=101|issue=1|pages=372–378|doi=10.1016/j.biortech.2009.07.048|pmid=19729299|issn=0960-8524|last1=Nerio|first1=Luz Stella|last2=Olivero-Verbel|first2=Jesus|last3=Stashenko|first3=Elena|bibcode=2010BiTec.101..372N }}</ref> These effects may include repelling, inhibiting digestion, stunting growth,<ref name="Regnault-Roger-et-al-2012">{{cite journal | last1=Regnault-Roger | first1=Catherine | last2=Vincent | first2=Charles | last3=Arnason | first3=John Thor | title=Essential Oils in Insect Control: Low-Risk Products in a High-Stakes World | journal=Annual Review of Entomology | volume=57 | issue=1 | date=2012-01-07 | issn=0066-4170 | doi=10.1146/annurev-ento-120710-100554 | pages=405–424 | pmid=21942843}}</ref> decreasing rate of reproduction, or death of pests that consume the oil. However, the molecules within the oils that cause these effects are normally non-toxic for mammals. These specific actions of the molecules allow for widespread use of these "green" pesticides without harmful effects to anything else other than pests.<ref name=":3">{{Cite journal|last=Regnault-Roger|first=Catherine|s2cid=39007186|date=1997-02-01|title=The potential of botanical essential oils for insect pest control|journal=Integrated Pest Management Reviews|language=en|volume=2|issue=1|pages=25–34|doi=10.1023/A:1018472227889|issn=1353-5226}}</ref> Essential oils that have been investigated include rose, lemon grass, lavender, thyme, peppermint, basil, cedarwood, and eucalyptus.<ref name="Koul-et-al-2008">{{cite journal | last1=Koul | first1=Opender | last2=Suresh | first2=Walia | first3=G. S. | last3=Dhaliwal | title=Essential Oils as Green Pesticides: Potential and Constraints |url=https://www.researchgate.net/publication/270157815 | journal=Biopesticides International | volume=4 | issue=1 | date=2008 | pages=63–84 | s2cid=85741148}}</ref>

Although they may not be the perfect replacement for all synthetic pesticides, essential oils have prospects for crop or indoor plant protection, urban pest control,<ref>{{Cite journal|date=2000-09-12|title=Plant essential oils for pest and disease management|journal=Crop Protection|language=en|volume=19|issue=8–10|pages=603–608|doi=10.1016/S0261-2194(00)00079-X|issn=0261-2194|last1=Isman|first1=Murray B|bibcode=2000CrPro..19..603I |s2cid=39469817 }}</ref> and marketed insect repellents, such as bug spray. Certain essential oils have been shown in studies to be comparable, if not exceeding, in effectiveness to DEET, which is currently marketed as the most effective mosquito repellent. Although essential oils are effective as pesticides when first applied in uses such as mosquito repellent applied to the skin, it is only effective in the vapor stage. Since this stage is relatively short-lived, creams and polymer mixtures are used in order to elongate the vapor period of effective repellency.<ref name=":0" />

In any form, using essential oils as green pesticides rather than synthetic pesticides has ecological benefits such as decreased residual actions.<ref name="Koul-et-al-2008" /> In addition, increased use of essential oils as pest control could have not only ecological, but economical benefits as the essential oil market diversifies<ref name=":3" /> and popularity increases among organic farmers and environmentally conscious consumers.<ref name="Regnault-Roger-et-al-2012" /> {{As of|2012}} some EOs are authorized, and in use, in the European Union: ''Melaleuca'' oil as a fungicide, citronella oil as a herbicide, ''Syzygium aromaticum'' oil as a fungicide and bactericide, ''Mentha spicata'' oil as a plant growth regulator; ''Citrus sinensis'' oil (only in France) for ''Bemisia tabaci'' on ''Cucurbita pepo'' and ''Trialeurodes vaporariorum'' on ''Solanum lycopersicum''; and approvals for oils of ''Thymus'', ''C. sinensis'', and ''Tagetes'' as insecticides are pending.<ref name="Regnault-Roger-et-al-2012" />

== Use in food == {{Globalize|date=June 2024}} In relation with their food applications, although these oils have been used throughout history as food preservatives, it was in the 20th century when essential oils were considered as Generally Recognized as Safe (GRAS) by the United States' Food and Drug Administration (FDA).<ref>{{Cite book|title=Essential oils in food preservation, flavor and safety|publisher=Academic Press|vauthors =Preedy VR|isbn=978-0-12-416644-8| location=Amsterdam |oclc=922581414|date = 2015-09-28}}</ref>

'''GRAS substances according to the FDA<ref name="US FDA" />''' {| class="wikitable" !Common name !Botanical name of plant source |- |Alfalfa |''Medicago sativa'' L. |- |Allspice |''Pimenta officinalis'' Lindl. |- |Bitter almond, free from cyanide<ref>{{cite web | url=https://www.spektrum.de/quiz/wieviel-prozent-blausaeure-enthaelt-natuerliches-bittermandeloel/594066 | title=Wieviel Prozent Blausäure enthält natürliches Bittermandelöl? }}</ref> |''Prunus amygdalus'' Batsch, ''Prunus armeniaca'' L., or ''Prunus persica'' (L.) Batsch. |- |Ambrette (seed) |Hibiscus moschatus Moench. |- |Angelica root |rowspan=3|''Angelica archangelica'' L. |- |Angelica seed |- |Angelica stem |- |Angostura (cusparia bark) |''Galipea officinalis'' Hancock, ''Angostura trifoliata'' |- |Anise |''Pimpinella anisum'' L. |- |Asafetida |''Ferula assa-foetida'' L. and related spp. of ''Ferula'' |- |Balm (lemon balm) |''Melissa officinalis'' L. |- |Balsam of Peru |''Myroxylon pereirae'' Klotzsch. |- |Basil |''Ocimum basilicum'' L. |- |Bay leaves |''Laurus nobilis'' L. |- |Bay (myrcia oil) |''Pimenta racemosa'' (Mill.) J. W. Moore. |- |Bergamot (bergamot orange) |''Citrus aurantium'' L. subsp. ''bergamia'' Wright et Arn. |- |Bitter almond (free from prussic acid) |''Prunus amygdalus'' Batsch, ''Prunus armeniaca'' L., or ''Prunus persica'' (L.) Batsch. |- |Bois de rose |''Aniba rosaeodora'' Ducke. |- |Cacao |''Theobroma cacao'' L. |- |Camomile (chamomile) flowers, German or Hungarian |''Matricaria chamomilla'' L. |- |Camomile (chamomile) flowers, Roman or English |''Anthemis nobilis'' L. |- |Cananga |''Cananga odorata'' Hook. f. and Thoms. |- |Capsicum |''Capsicum frutescens'' L. and ''Capsicum annuum'' L. |- |Caraway |''Carum carvi'' L. |- |Cardamom seed (cardamon) |''Elettaria cardamomum'' Maton. |- |Carob bean |''Ceratonia siliqua'' L. |- |Carrot |''Daucus carota'' L. |- |Cascarilla bark |''Croton eluteria'' Benn. |- |Cassia bark, Chinese |''Cinnamomum cassia'' Blume. |- |Cassia bark, Padang or Batavia |''Cinnamomum burmanni'' Blume. |- |Cassia bark, Saigon |''Cinnamomum loureirii'' Nees. |- |Celery seed |''Apium graveolens'' L. |- |Cherry, wild, bark |''Prunus serotina'' Ehrh. |- |Chervil |''Anthriscus cerefolium'' (L.) Hoffm. |- |Chicory |''Cichorium intybus'' L. |- |Cinnamon bark, Ceylon |''Cinnamomum zeylanicum'' Nees. |- |Cinnamon bark, Chinese |''Cinnamomum cassia'' Blume. |- |Cinnamon bark, Saigon |''Cinnamomum loureirii'' Nees. |- |Cinnamon leaf, Ceylon |''Cinnamomum zeylanicum'' Nees. |- |Cinnamon leaf, Chinese |''Cinnamomum cassia'' Blume. |- |Cinnamon leaf, Saigon |''Cinnamomum loureirii'' Nees. |- |Citronella |''Cymbopogon nardus'' Rendle. |- |Citrus peels |''Citrus'' spp. |- |Clary (clary sage) |''Salvia sclarea'' L. |- |Clover |''Trifolium'' spp. |- |Coca (decocainized) |''Erythroxylum coca'' Lam. and other spp. of ''Erythroxylum'' |- |Coffee |''Coffea'' spp. |- |Cola nut |''Cola acuminata'' Schott and Endl., and other spp. of ''Cola'' |- |Coriander |''Coriandrum sativum'' L. |- |Cumin (cummin) |''Cuminum cyminum'' L. |- |Curaçao orange peel (orange, bitter peel) |''Citrus aurantium'' L. |- |Cusparia bark |''Galipea officinalis'' Hancock |- |Dandelion |rowspan=2|''Taraxacum officinale'' Weber and ''Taraxacum laevigatum'' DC. |- |Dandelion root |- |Dog grass (quackgrass, triticum) |''Agropyron repens'' (L.) Beauv. |- |Elder flowers |''Sambucus canadensis'' L. and ''Sambucus nigra'' I. |- |Estragole (esdragol, esdragon, tarragon) |rowspan=2|''Artemisia dracunculus'' L. |- |Estragon (tarragon) |- |Fennel, sweet |''Foeniculum vulgare'' Mill. |- |Fenugreek |''Trigonella foenum-graecum'' L. |- |Galanga (galangal) |''Alpinia officinarum'' Hance. |- |Geranium |''Pelargonium'' spp. |- |Geranium, East Indian |''Cymbopogon martini'' Stapf. |- |Geranium, rose |''Pelargonium graveolens'' L'Her. |- |Ginger |''Zingiber officinale'' Rosc. |- |Grapefruit |''Citrus paradisi'' Macf. |- |Guava |''Psidium'' spp. |- |Hickory bark |''Carya'' spp. |- |Horehound (hoarhound) |''Marrubium vulgare'' L. |- |Hops |''Humulus lupulus'' L. |- |Horsemint |''Monarda punctata'' L. |- |Hyssop |''Hyssopus officinalis'' L. |- |Immortelle |''Helichrysum augustifolium'' DC. |- |Jasmine |''Jasminum officinale'' L. and other spp. of ''Jasminum'' |- |Juniper (berries) |''Juniperus communis'' L. |- |Kola nut |''Cola acuminata'' Schott and Endl., and other spp. of ''Cola'' |- |Laurel berries |''Laurus nobilis'' L. |- |Laurel leaves |''Laurus'' spp. |- |Lavender |''Lavandula officinalis'' Chaix |- |Lavender, spike |''Lavandula latifolia'' Vill. |- |Lavandin |Hybrids between ''Lavandula officinalis'' Chaix and ''Lavandula latifolin'' Vill. |- |Lemon |''Citrus limon'' (L.) Burm. f. |- |Lemon balm (see balm) |''Melissa officinalis'' L. |- |Lemongrass |''Cymbopogon citratus'' DC. and ''Cymbopogon lexuosus'' Stapf. |- |Lemon peel |''Citrus limon'' (L.) Burm. f. |- |Lime |''Citrus aurantifolia'' Swingle. |- |Linden flowers |''Tilia'' spp. |- |Locust bean |''Ceratonia siliqua'' L, |- |Lupulin |''Humulus lupulus'' L. |- |Mace |''Myristica fragrans'' Houtt. |- |Mandarin |''Citrus reticulata'' Blanco. |- |Marjoram, sweet |''Majorana hortensis'' Moench. |- |Mate, yerba |''Ilex paraguariensis'' St. Hil. |- |Melissa (see balm) | |- |Menthol |rowspan=2|''Mentha'' spp. |- |Menthyl acetate |- |Molasses (extract) |''Saccharum officinarum'' L. |- |Mustard |''Brassica'' spp. |- |Naringin |''Citrus paradisi'' Macf. |- |Neroli, bigarade |''Citrus aurantium'' L. |- |Nutmeg |''Myristica fragrans'' Houtt. |- |Onion |''Allium cepa'' L. |- |Orange, bitter, flowers |rowspan=2|''Citrus aurantium'' L. |- |Orange, bitter, peel |- |Orange leaf |rowspan=4|''Citrus sinensis'' (L.) Osbeck. |- |Orange, sweet |- |Orange, sweet, flowers |- |Orange, sweet, peel |- |Origanum |''Origanum'' spp. |- |Palmarosa |''Cymbopogon martini'' Stapf. |- |Paprika |''Capsicum annuum'' L. |- |Parsley |''Petroselinum crispum'' (Mill.) Mansf. |- |Pepper, black |rowspan=2|''Piper nigrum'' L. |- |Pepper, white |- |Peppermint |''Mentha piperita'' L. |- |Peruvian balsam |''Myroxylon pereirae'' Klotzsch. |- |Petitgrain |''Citrus aurantium'' L. |- |Petitgrain lemon |''Citrus limon'' (L.) Burm. f. |- |Petitgrain mandarin or tangerine |''Citrus reticulata'' Blanco. |- |Pimenta |rowspan=2|''Pimenta officinalis'' Lindl. |- |Pimenta leaf |- |Pipsissewa leaves |''Chimaphila umbellata'' Nutt. |- |Pomegranate |''Punica granatum'' L. |- |Prickly ash bark |''Xanthoxylum'' (or ''Zanthoxylum'') ''americanum'' Mill. or ''Xanthoxylum clava-herculis'' L. |- |Rose absolute |rowspan=5|''Rosa alba'' L., ''Rosa centifolia'' L., ''Rosa damascena'' Mill., ''Rosa gallica'' L., and vars. of these spp. |- |Rose (otto of roses, attar of roses) |- |Rose buds |- |Rose flowers |- |Rose fruit (hips) |- |Rose geranium |''Pelargonium graveolens'' L'Her. |- |Rose leaves |''Rosa'' spp. |- |Rosemary |''Rosmarinus officinalis'' L. |- |Saffron |''Crocus sativus'' L. |- |Sage |''Salvia officinalis'' L. |- |Sage, Greek |''Salvia triloba'' L. |- |Sage, Spanish |''Salvia officinalis'' subsp. ''lavandulifolia'' (Vahl) Gams |- |Carob |''Ceratonia siliqua'' L. |- |Savory, summer |''Satureia hortensis'' L. |- |Savory, winter |''Satureia montana'' L. |- |''Schinus molle'' |''Schinus molle'' L. |- |Sloe berries (blackthorn berries) |''Prunus spinosa'' L. |- |Spearmint |''Mentha spicata'' L. |- |Spike lavender |''Lavandula latifolia'' Vill. |- |Tamarind |''Tamarindus indica'' L. |- |Tangerine |''Citrus reticulata'' Blanco. |- |Tarragon |''Artemisia dracunculus'' L. |- |Tea |''Thea sinensis'' L. |- |Thyme |rowspan=2|''Thymus vulgaris'' L. and ''Thymus zygis'' var. ''gracilis'' Boiss. |- |Thyme, white |- |Thyme, wild or creeping |''Thymus serpyllum'' L. |- |Triticum (see dog grass) |''Elymus repens'' |- |Tuberose |''Polianthes tuberosa'' L. |- |Turmeric |''Curcuma longa'' L. |- |Vanilla |''Vanilla planifolia'' Andr. or ''Vanilla tahitensis'' J. W. Moore. |- |Violet flowers |rowspan=3|''Viola odorata'' L. |- |Violet leaves |- |Violet leaves absolute |- |Wild cherry bark |''Prunus serotina'' Ehrh. |- |Ylang-ylang |''Cananga odorata'' Hook. f. and Thoms. |- |Zedoary bark |''Curcuma zedoaria'' Rosc. |}

===As antimicrobials=== The most commonly used essential oils with antimicrobial action are: phenol-rich EOs such as ''Thymus'' spp. ''Origanum'' spp., ''Satureja'' spp., phenylpropene-rich EOs such as ''Cinnamomum verum cortex'' and ''leaves'', ''Syzygium aromaticum'', and alcohol-rich EOs such as ''Melaleuca alternifolia'', ''Lavandula x intermedia'', ''Lavandula angustifolia, Pelargonium'' spp., etc.: important antimicrobial compounds are eugenol, eugenol acetate, carvacrol, linalool, thymol, geraniol, cinnamaldehyde, geranial, neral, 1,8-cineole, methyl chavicol, methyl cinnamate, methyl eugenol, camphor, α-thujone, (''Z'')-linalool oxide.<ref name="Rao-et-al-2019" />

Some essential oils are effective antimicrobials and have been evaluated for food incorporation in vitro. However, actual deployment is rare because much higher concentrations are required in real foods. Some or all of this lower effectiveness is due to large differences between culture medium and foods in chemistry (especially lipid content), viscosity, and duration of inoculation/storage.<ref name="Rao-et-al-2019">{{cite journal | last1=Rao | first1=Jiajia | last2=Chen | first2=Bingcan | last3=McClements | first3=David Julian | author3-link=David J. McClements | title=Improving the Efficacy of Essential Oils as Antimicrobials in Foods: Mechanisms of Action | journal=Annual Review of Food Science and Technology | volume=10 | issue=1 | date=2019-03-25 | issn=1941-1413 | doi=10.1146/annurev-food-032818-121727 | pages=365–387| pmid=30653350 | s2cid=58656780 | doi-access=free }}</ref>

==Dilution==

Essential oils are usually lipophilic (literally: ''"oil-loving"'') compounds that are immiscible (not miscible) with water. They can be diluted in solvents like pure ethanol and polyethylene glycol.{{citation needed|date=May 2021}}

==Raw materials== {{main|List of essential oils}}

Essential oils are derived from sections of plants. Some plants, like the bitter orange, are sources of several types of essential oil.

:{| class="wikitable" | | valign="top" | ;Bark * Cassia * Cinnamon * Sassafras

;Berries * Allspice * Juniper

;Flowers * Cannabis * Chamomile * Clary sage * Clove * Hops * Hyssop * Jasmine * Lavender * Manuka * Marjoram * Orange * Pelargonium (Scented geranium) * Plumeria * Rose * Ylang-ylang | valign="top" |

;Leaves * Basil * Bay leaf * Buchu * Cinnamon * Common sage * Eucalyptus * Guava * Lemon grass * Melaleuca * Oregano * rose * bergamot * Patchouli * Peppermint * Pine * Rosemary * Spearmint * Tea tree * Thyme * Tsuga * Wintergreen ;Peel * Bergamot * Grapefruit * Lemon * Lime * Orange * Tangerine | valign="top" |

;Resin

*Benzoin * Copaiba * Frankincense * Labdanum * Myrrh

;Rhizome

*Galangal * Ginger

;Roots

*Valerian

;Seeds

*Anise * Buchu * Celery * Cumin * Flax * Nutmeg oil

;Woods

*Agarwood * Camphor * Cedar * Rosewood * Sandalwood |}

===Balsam of Peru=== Balsam of Peru, an essential oil derived from ''Myroxylon'' plants, is used in food and drink for flavoring, in perfumes and toiletries for fragrance, and in animal care products.<ref>{{Cite web|date=11 December 2021|title=Balsam of Peru|url=https://go.drugbank.com/drugs/DB11482|publisher=DrugBank|access-date=2021-12-15|website=go.drugbank.com}}</ref> However, national and international surveys identified balsam of Peru among the "top five" allergens most commonly causing patch test allergic reactions in people referred to dermatology clinics.<ref name="Gottfried2008">{{cite book |title= Biocompatibility of Dental Materials |chapter= Diagnosis of Side Effects of Dental Materials, with Special Emphasis on Delayed and Immediate Allergic Reactions |chapter-url= https://books.google.com/books?id=mrreTHuo54wC&pg=PA352 |first1= D |last1= Arenholt-Bindslev |first2= R |last2= Jolanki |first3= L |last3= Kanerva |date= 2009 |editor-first1= Gottfried |editor-last1= Schmalz |editor-first2= Dorthe |editor-last2= Arenholt-Bindslev |publisher= Springer |page= 352 |access-date= March 5, 2014 |isbn= 978-3-540-77782-3 |doi= 10.1007/978-3-540-77782-3_14 |url-status= live |archive-url= https://web.archive.org/web/20160518233136/https://books.google.com/books?id=mrreTHuo54wC&pg=PA352 |archive-date= May 18, 2016 }}</ref><ref name="Habif2009">{{cite book|last=Habif|first=Thomas P.|url=https://books.google.com/books?id=kDWlWR5UbqQC&q=%22balsam+of+peru%22+allergy&pg=PT530|title=Clinical Dermatology|publisher=Elsevier Health Sciences|year=2009|isbn=978-0-323-08037-8|access-date=March 6, 2014}}</ref><ref>{{cite book|last1=Yiannias|first1=JA|title=Conn's Current Therapy 2014: Expert Consult|publisher=Elsevier Health Sciences|year=2013|isbn=978-0-323-22572-4|editor-last1=Bope|editor-first1=Edward T.|chapter=Contact Dermatitis|editor-last2=Kellerman|editor-first2=Rick D.|chapter-url=https://books.google.com/books?id=fmwYAgAAQBAJ&pg=PT264}}</ref>

===Garlic oil=== Garlic oil is an essential oil derived from garlic.<ref name="Linskens Adams Crespo Jackson 2012 p. 105">{{cite book | last1=Linskens | first1=H.F. | last2=Adams | first2=R.P. | last3=Crespo | first3=M.E. | last4=Jackson | first4=J.F. | last5=Deans | first5=S.G. | last6=Dobson | first6=H.E.M. | last7=Dunlop | first7=P. | last8=Erdelmeier | first8=C.A.J. | last9=Ghosh | first9=A. | last10=Hammond | first10=E.G. | title=Essential Oils and Waxes | publisher=Springer Berlin Heidelberg | series=Molecular Methods of Plant Analysis | year=2012 | isbn=978-3-642-84023-4 | url=https://books.google.com/books?id=eKz1CAAAQBAJ&pg=PA105 | access-date=December 29, 2017 | page=105}}</ref>

===Eucalyptus oil=== {{main|Eucalyptus oil}}

Most eucalyptus oil on the market is produced from the leaves of ''Eucalyptus globulus''. Steam-distilled eucalyptus oil is used throughout Asia, Africa, Latin America and South America as a primary cleaning/disinfecting agent added to soaped mop and countertop cleaning solutions; it also possesses insect and limited vermin control properties.<ref>{{cite journal |title=Eucalyptus essential oil as a natural pesticide |first1=Daizy R. |last1=Batish |first2=Harminder Pal |last2=Singh |first3=Ravinder Kumar |last3=Kohlia |first4=Shalinder |last4=Kaur |journal=Forest Ecology and Management |volume=256 |issue=12 |date=10 December 2008 |pages=2166–2174 |doi=10.1016/j.foreco.2008.08.008 |bibcode=2008ForEM.256.2166B }}</ref> Note, however, there are hundreds of species of eucalyptus, and perhaps some dozens are used to various extents as sources of essential oils. Not only do the products of different species differ greatly in characteristics and effects, but also the products of the very same tree can vary grossly.<ref name=Thorpe1>{{cite book |title= Thorpe's Dictionary of Applied Chemistry |volume= 8 |edition= 4th |publisher= Longmans Green |year= 1947}}{{page needed|date= October 2014}}</ref>

===Lavender oil=== {{main|Lavender oil}}

[[File:Marchés des Producteurs de Pays 11 16 14.jpg|thumb|Lavender essential oil sold at a market in France]] Lavender oil has long been used in the production of perfume.<ref>N. Groom. New Perfume Handbook. Springer Science & Business Media, 1997 {{ISBN|9780751404036}}, pp. 184-186</ref> However, studies have shown it can be estrogenic and antiandrogenic, causing problems for prepubescent boys and pregnant women, in particular.<ref>{{cite journal|date=2007|title=Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils|journal=New England Journal of Medicine|volume=356|issue=5|pages=479–485|doi=10.1056/NEJMoa064725|pmid=17267908|last1=Henley|first1=Derek V|last2=Lipson|first2=Natasha|last3=Korach|first3=Kenneth S|last4=Bloch|first4=Clifford A|doi-access=free}}</ref> Lavender essential oil is also used as an insect repellent.<ref>{{cite book | title=Insect Repellents Handbook | editor1=Debboun, Mustapha | editor2=Frances, Stephen P. | editor3=Strickman, Daniel | publisher=CRC Press | year=2014 | edition=2nd | isbn=978-1-4665-5355-2 | page=362 }}</ref>

===Rose oil=== {{main|Rose oil}}

There are two major species of rose whose petals used for the production of Rose oil; ''Rosa damascena'' and ''Rosa centifolia''.<ref>{{cite journal |last1=Mohebitabar |first1=S |last2=Shirazi |first2=M |last3=Bioos |first3=S |last4=Rahimi |first4=R |last5=Malekshahi |first5=F |last6=Nejatbakhsh |first6=F |title=Therapeutic efficacy of rose oil: A comprehensive review of clinical evidence. |journal=Avicenna Journal of Phytomedicine |date=May 2017 |volume=7 |issue=3 |pages=206–213 |pmid=28748167 |pmc=5511972 }}</ref> Rose oils can be classified according to their botanical name, their place of origin and their extraction process. Steam-distilled rose oil is known as "rose otto", while the solvent extracted oil is known as "rose absolute". Rose otto is extracted through hydro-distillation, in which Rosa damascena petals are slowly heated with water. The heat causes the petals to release the essential rose oil. When cooled, the oil (rose otto) floats to the surface of the water (rose hydrosol). In contrast, rose absolute is solvent-extracted. Rose petals are combined with an organic solvent in a slowly rotating drum to draw out the aromatic matter from the flowers. After the solvent is evaporated, the waxy substance remaining is called rose concrete. Rose concrete is filtered with ethanol alcohol to remove waxes and non-aromatic components and leave behind the liquid known as rose absolute.<ref>{{cite journal |last1=Nedeltcheva-Antonova |first1=Daniela |last2=Stoicheva |first2=Petya |last3=Antonov |first3=Liudmil |title=Chemical profiling of Bulgarian rose absolute (''Rosa damascena'' Mill.) using gas chromatography–mass spectrometry and trimethylsilyl derivatives |journal=Industrial Crops and Products |date=1 December 2017 |volume=108 |pages=36–43 |doi=10.1016/j.indcrop.2017.06.007 |url=https://www.sciencedirect.com/science/article/abs/pii/S092666901730393X |issn=0926-6690|url-access=subscription }}</ref>

==Toxicity==  The potential toxicity of essential oil is related to the toxicity of specific chemical components of the oil, and to its level or grade of purity.<ref name=poison.org/> Industrial users of essential oils should consult the safety data sheets to determine the hazards and handling requirements of particular oils.<ref name=poison.org/>

Some essential oils, even at extremely low levels, can pose health threats for pregnant women, those who are breastfeeding, those with estrogen-dependent cancers or individuals with epilepsy.<ref name="Dosoky"/><ref name="Rana"/> Essential oil use in children can pose a danger when misused because of their thin skin and developing livers.<ref name="Alnuqaydan">{{cite journal |last1=Alnuqaydan |first1=AM |title=The dark side of beauty: an in-depth analysis of the health hazards and toxicological impact of synthetic cosmetics and personal care products. |journal=Frontiers in Public Health |date=2024 |volume=12 |article-number=1439027 |doi=10.3389/fpubh.2024.1439027 |doi-access=free |pmid=39253281 |pmc=11381309 |bibcode=2024FrPH...1239027A }}</ref> This might cause them to be more susceptible to toxic effects than adults.<ref name="poison.org"/>

Some essential oils can cause severe irritation, provoke an allergic reaction and, over time, prove toxic to the liver. If ingested or rubbed into the skin, essential oils can be toxic, causing confusion, choking, loss of muscle coordination, difficulty in breathing, pneumonia, seizures, and possibly severe allergic reactions or coma.<ref name=poison.org/>

Some essential oils, including many of the citrus peel oils, are photosensitizers, increasing vulnerability of the skin to sunlight.<ref name="KadduKerl2001">{{cite journal |doi=10.1067/mjd.2001.116226 |pmid=11511848 |title=Accidental bullous phototoxic reactions to bergamot aromatherapy oil |journal=Journal of the American Academy of Dermatology |volume=45 |issue=3 |pages=458–61 |year=2001 |last1=Kaddu |first1=Steven |last2=Kerl |first2=Helmut |last3=Wolf |first3=Peter }}</ref>

===Flammability=== The flash point of each essential oil is different. Many of the common essential oils, such as tea tree, lavender, and citrus oils,<ref>{{cite web |title=Safety Data Sheet Organic Tea Tree Essential Oil (Melaleuca alternifolia) |url=https://www.nhrorganicoils.com/uploads/20221202134851e_Tea_Tree_SDS.pdf |website=NHR |access-date=4 December 2025}}</ref><ref>{{cite web |title=Safety Data Sheet Organic English Lavender Essential Oil (Lavandula angustifolia) |url=https://www.nhrorganicoils.com/uploads/20211018152840e_Lavender_English_SDS.pdf |website=NHR |access-date=4 December 2025}}</ref><ref>{{cite web |title=Material Safety Data Sheet: Organic Orange Oil Sweet |url=https://www.nhrorganicoils.com/uploads/20201221151223e_20151214115021e_Orange_SDS.pdf |website=NHR |access-date=4 December 2025}}</ref> are classed as Class 3 Flammable Liquids, as they have a flash points at or below 60 °C.<ref>{{cite web |title=Hazard Class 3: Flammable Liquids {{!}} Environment, Health and Safety |url=https://ehs.cornell.edu/shipping-and-transportation/hazardous-materials-shipping/hazard-class-3-flammable-liquids |website=Environment, Health and Safety, Cornell University |access-date=4 December 2025}}</ref>

===Gynecomastia=== Estrogenic and antiandrogenic activity have been reported by ''in vitro'' study of tea tree oil and lavender essential oils. Two published sets of case reports suggest that lavender oil may be implicated in some cases of gynecomastia, an abnormal breast tissue growth in prepubescent boys.<ref>{{cite journal |doi=10.1056/NEJMoa064725 |pmid=17267908 |title=Prepubertal Gynecomastia Linked to Lavender and Tea Tree Oils |journal=New England Journal of Medicine |volume=356 |issue=5 |pages=479–85 |year=2007 |last1=Henley |first1=Derek V. |last2=Lipson |first2=Natasha |last3=Korach |first3=Kenneth S. |last4=Bloch |first4=Clifford A. |doi-access=free }}</ref><ref>{{cite journal |vauthors=Diaz A, Luque L, Badar Z, Kornic S, Danon M |s2cid=19454282 |title=Prepubertal gynecomastia and chronic lavender exposure: report of three cases |journal=J. Pediatr. Endocrinol. Metab. |volume=29 |issue=1 |pages=103–107 |date=2016 |pmid=26353172 |doi=10.1515/jpem-2015-0248 }}</ref> The European Commission's Scientific Committee on Consumer Safety dismissed the claims against tea tree oil as implausible, but did not comment on lavender oil.<ref>{{citation|author=Scientific Committee on Consumer Products|title=Opinion on tea tree oil|date=December 16, 2008|url=http://ec.europa.eu/health/archive/ph_risk/committees/04_sccp/docs/sccp_o_160.pdf|issue=Report No. SCCP/1155/08|publisher=Directorate-General for Health and Consumers: European Commission: European Union}}</ref> In 2018, a BBC report on a study stated that tea tree and lavender oils contain eight substances that when tested in tissue culture experiments, increasing the level of estrogen and decreasing the level of testosterone. Some of the substances are found in "at least 65 other essential oils". The study did not include animal or human testing.<ref>{{Cite news|title=More evidence essential oils 'make male breasts develop'|url=https://www.bbc.co.uk/news/health-43429933|publisher=BBC|access-date=18 March 2018|date=18 March 2018|quote=A suspected link between abnormal breast growth in young boys and the use of lavender and tea tree oils has been given new weight, after a study found eight chemicals contained in the oils interfere with hormones.|work=BBC News}}</ref>

===Handling=== Exposure to essential oils may cause contact dermatitis.<ref name="ReferenceA"/><ref name="ReferenceB"/><ref name="ReferenceC"/> Essential oils can be aggressive toward rubbers and plastics, so care must be taken in choosing the correct handling equipment. Glass syringes are often used, but have coarse volumetric graduations. Chemistry syringes are ideal, as they resist essential oils, are long enough to enter deep vessels, and have fine graduations, facilitating quality control. Unlike traditional pipettes, which have difficulty handling viscous fluids, the chemistry syringe, also known as a positive displacement pipette, has a seal and piston arrangement which slides inside the pipette, wiping the essential oil off the pipette wall.

===Ingestion=== Some essential oils qualify as GRAS flavoring agents for use in foods, beverages, and confectioneries according to strict good manufacturing practice and flavorist standards.<ref name="US FDA">{{Cite web|url=https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=182.20|archive-url=https://web.archive.org/web/20030915162222/http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?FR=182.20|archive-date=September 15, 2003|title=CFR - Code of Federal Regulations Title 21|website=www.accessdata.fda.gov|access-date=2018-12-08}} {{PD-notice}}</ref> Pharmacopoeia standards for medicinal oils should be heeded.<ref name="Ali">{{cite journal |last1=Ali |first1=S |last2=Ekbbal |first2=R |last3=Salar |first3=S |last4=Yasheshwar |last5=Ali |first5=SA |last6=Jaiswal |first6=AK |last7=Singh |first7=M |last8=Yadav |first8=DK |last9=Kumar |first9=S |last10=Gaurav |title=Quality Standards and Pharmacological Interventions of Natural Oils: Current Scenario and Future Perspectives. |journal=ACS Omega |date=31 October 2023 |volume=8 |issue=43 |pages=39945–39963 |doi=10.1021/acsomega.3c05241 |doi-access=free|pmid=37953833 |pmc=10635672 }}</ref>

The internal use of essential oils can pose hazards to pregnant women, as some can be abortifacients or cause fetal damage, and thus should not be used during pregnancy.<ref name="Dosoky">{{cite journal |last1=Dosoky |first1=NS |last2=Setzer |first2=WN |title=Maternal Reproductive Toxicity of Some Essential Oils and Their Constituents. |journal=International Journal of Molecular Sciences |date=27 February 2021 |volume=22 |issue=5 |page=2380 |doi=10.3390/ijms22052380 |doi-access=free |pmid=33673548 |pmc=7956842 }}</ref> Some oils can be toxic to some domestic animals, cats in particular.<ref>{{cite journal |doi=10.1177/104063879801000223 |pmid=9576358 |title=Australian Tea Tree (Melaleuca Alternifolia) Oil Poisoning in Three Purebred Cats |journal=Journal of Veterinary Diagnostic Investigation |volume=10 |issue=2 |pages=208–10 |year=1998 |last1=Bischoff |first1=K. |last2=Guale |first2=Fessesswork |doi-access=free }}</ref>

===Pesticide residues=== Concern about pesticide residues in essential oils, particularly those used therapeutically, means many practitioners of aromatherapy buy organically produced oils. Not only are pesticides present in trace quantities, but also the oils themselves are used in tiny quantities and usually in high dilutions. Where there is a concern about pesticide residues in food essential oils, such as mint or orange oils, the proper criterion is not solely whether the material is organically produced, but whether it meets the government standards based on actual analysis of its pesticide content.<ref>{{cite book |last= Menary |first= RC |title= Minimising pesticide residues in essential oils |year= 2008 |publisher= Rural Industries Research and Development Corporation |isbn= 978-1-74151-709-5}}{{page needed|date= October 2014}}</ref>

===Pregnancy=== Some essential oils should not be used by pregnant or breastfeeding women, because they can be abortifacients, cause fetal damage, or disrupt hormones.<ref name="Dosoky"/> Key components of essential oils and whole essential oils do not always have the same hormonal effects. Minor compounds in whole oils may have both individual or group (synergistic) effects.<ref name="Fouyet">{{cite journal |last1=Fouyet |first1=S |last2=Olivier |first2=E |last3=Leproux |first3=P |last4=Dutot |first4=M |last5=Rat |first5=P |title=Evaluation of Placental Toxicity of Five Essential Oils and Their Potential Endocrine-Disrupting Effects. |journal=Current Issues in Molecular Biology |date=28 June 2022 |volume=44 |issue=7 |pages=2794–2810 |doi=10.3390/cimb44070192 |doi-access=free |pmid=35877416 |pmc=9323951 }}</ref> Some essential oils may contain impurities or additives that may be harmful.<ref name="Iordache">{{cite journal |last1=Iordache |first1=Andreea Maria |last2=Nechita |first2=Constantin |last3=Voica |first3=Cezara |last4=Roba |first4=Carmen |last5=Botoran |first5=Oana Romina |last6=Ionete |first6=Roxana Elena |title=Assessing the Health Risk and the Metal Content of Thirty-Four Plant Essential Oils Using the ICP-MS Technique |journal=Nutrients |date=7 June 2022 |volume=14 |issue=12 |page=2363 |doi=10.3390/nu14122363 |pmid=35745094 |pmc=9229550 |doi-access=free |issn=2072-6643}}</ref> Some uses of essential oils may be safe during pregnancy (e.g. smelling lavender to reduce stress<ref>{{cite journal |last1=Vidal-García |first1=E |last2=Vallhonrat-Bueno |first2=M |last3=Pla-Consuegra |first3=F |last4=Orta-Ramírez |first4=A |title=Efficacy of Lavender Essential Oil in Reducing Stress, Insomnia, and Anxiety in Pregnant Women: A Systematic Review |journal=Healthcare (Basel, Switzerland) |date=5 December 2024 |volume=12 |issue=23 |page=2456 |doi=10.3390/healthcare12232456 |doi-access=free |pmid=39685078 |pmc=11641599 |issn=2227-9032}}</ref>), but care must be taken when selecting quality and brand.

Sensitivity to certain smells may cause pregnant women to have adverse side effects with essential oil use, such as headache, vertigo, and nausea. Pregnant women often report a heightened sensitivity to smells and taste,<ref name="Kwon">{{cite journal |last1=Kwon |first1=D |last2=Fessler |first2=DMT |last3=Knorr |first3=DA |last4=Wiley |first4=KS |last5=Sartori |first5=J |last6=Coall |first6=DA |last7=Fox |first7=MM |title=Of scents and cytokines: How olfactory and food aversions relate to nausea and immunomodulation in early pregnancy. |journal=Evolution, Medicine, and Public Health |date=2025 |volume=13 |issue=1 |pages=269–280 |doi=10.1093/emph/eoaf016 |pmid=41017872 |pmc=12476167 }}</ref> and essential oils can cause irritation and nausea if ingested.<ref name="poison.org" />

===Toxicology=== The following table lists the {{LD50}} or median lethal dose for common oils; this is the dose required to kill half the members of a tested animal population. LD50 is intended as a guideline only, and reported values can vary widely due to differences in tested species and testing conditions.<ref>{{Cite journal |url= http://www.zenitech.com/documents/Toxicity_of_essential_oils_p1.pdf |title= Toxicology of essential oils reviewed |date= September 2009 |journal= Personal Care |first= AC |last= Dweck |archive-url= https://web.archive.org/web/20110718152502/http://www.zenitech.com/documents/Toxicity_of_essential_oils_p1.pdf |archive-date= 2011-07-18 |access-date= 2011-01-05 }}</ref> {| class="wikitable" |- ! Common name !! Oral LD50!! Dermal LD50 !! Notes |- | Neem || 14 mg/kg|| >2 mg/kg || |- | Lemon myrtle || 2.43 mg/kg || 2.25 mg/kg || |- | Frankincense || >5 mg/kg || >5 mg/kg || ''Boswellia carterii'' |- | Frankincense || >2 mg/kg || >2 mg/kg || ''Boswellia sacra'' |- | Indian frankincense || >2 mg/kg || >2 mg/kg || ''Boswellia serrata'' |- | Ylang-ylang || >5 mg/kg || >5 mg/kg || |- | Cedarwood || >5 mg/kg || >5 mg/kg || |- | Roman chamomile || >5 mg/kg || >5 mg/kg || |- | White camphor || >5 mg/kg || >5 mg/kg || ''Cinnamomum camphora'', extracted from leaves |- | Yellow camphor || 3.73 mg/kg || >5 mg/kg || ''Cinnamomum camphora'', extracted from bark |- | Hot oil || 3.80 mg/kg || >5 mg/kg || ''Cinnamomum camphora'', oil extracted from leaves |- | Cassia || 2.80 mg/kg || 0.32 mg/kg || |}

==Standardization of derived products== {{Further|British Pharmacopoeia|United States Pharmacopoeia}} In 2002, ISO published ISO 4720 in which the botanical names of the relevant plants are standardized.<ref name="eoni">{{cite web|title=ISO 4720:2002 Essential oils – Nomenclature|url=http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?ics1=01&ics2=040&ics3=71&csnumber=30435|author=International Organization for Standardization|author-link=International Organization for Standardization|access-date=April 23, 2009}}</ref> The rest of the standards with regards to this topic can be found in the section of ICS 71.100.60.<ref name="eo">{{cite web|title=71.100.60: Essential oils|url=http://www.iso.org/iso/products/standards/catalogue_ics_browse.htm?ICS1=71&ICS2=100&ICS3=60&|author=International Organization for Standardization|author-link=International Organization for Standardization|access-date=June 14, 2009}}</ref>

==History== {{more citations needed section|date=November 2021}}

The resins of aromatics and plant extracts were retained to produce traditional medicines and scented preparations, such as perfumes and incense, including frankincense, myrrh, cedarwood, juniper berry and cinnamon.<ref name="BaserBuchbauer2009">{{cite book | author1 = K. Husnu Can Baser | author2 = Gerhard Buchbauer | date = 28 December 2009 | title = Handbook of Essential Oils: Science, Technology, and Applications | publisher = CRC Press | pages = | isbn = 978-1-4200-6316-5 | url = https://books.google.com/books?id=2AEtSKfB2nUC}}</ref>{{Better source needed|date=December 2025}} Essential oils have been used in folk medicine over centuries. The Persian physician Ibn Sina, known as Avicenna in Europe, was first to derive the fragrance of flowers from distillation,<ref>{{Cite book|url=https://books.google.com/books?id=WMvVBi5EbhMC&q=attar+perfume+muslim&pg=PA70|title=Studies in Islamic Civilization: The Muslim Contribution to the Renaissance|last1=Essa|first1=Ahmed|last2=Ali|first2=Othman|date=2010|publisher=International Institute of Islamic Thought (IIIT)|isbn=978-1-56564-350-5|language=en|page=70}}</ref> while the earliest recorded mention of the techniques and methods used to produce essential oils may be Ibn al-Baitar (1188–1248), an Arab Al-Andalusian (Muslim Spain) physician, pharmacist and chemist.<ref name="Houtsma1993">{{cite book |first= M.Th. |last= Houtsma |title= E. J. Brill's First Encyclopaedia of Islam, 1913–1936 |volume= 4 |year= 1993 |publisher= Brill |isbn= 978-90-04-09790-2 |pages=1011– }}</ref>

Rather than refer to essential oils themselves, modern works typically discuss specific chemical compounds of which the essential oils are composed, such as referring to methyl salicylate rather than "oil of wintergreen".<ref name="G&G">{{cite book |editor1-last=Gilman |editor1-first=A. G. |editor2-last=Rall |editor2-first=T. W. |editor3-last=Nies |editor3-first=Alan S. |editor4-last=Taylor |editor4-first=Palmer |title=Goodman & Gilman's The Pharmacological Basis of Therapeutics |edition=8th |publisher=Pergamon |location=New York |year=1990 |isbn=978-0-08-040296-3|title-link=Goodman & Gilman's The Pharmacological Basis of Therapeutics }} {{page needed|date= October 2014}}</ref><ref name="isbn0-07-105239-9">{{cite book |last1= Klaassen |first1= Curtis D. |last2= Amdur |first2= Mary O. |last3= Casarett |first3= Louis J. |last4= Doull |first4= John |title= Casarett and Doull's Toxicology: The Basic Science of Poisons |publisher= McGraw-Hill |location= New York |year= 1991 |isbn= 978-0-07-105239-9}}{{page needed|date= October 2014}}</ref>

==See also== {{Commons category|Essential oils}} {{Wikibooks|Complete Guide to Essential Oils}} * Aroma lamp * Enfleurage * Fragrance oil * List of essential oils * Tincture * Volatility

==References== {{Reflist}}

==Further reading== * {{cite book | author=Baser, K.H.C. | author2=G. Buchbauer | title=Handbook of Essential Oils: Science, Technology and Applications | publisher=CRC Press, Boca Raton, London, New York | year=2010 | isbn= 978-1-4200-6315-8 }} * {{cite book | author=Schnaubelt, Kurt | title=Advanced Aromatherapy: The Science of Essential Oil Therapy | publisher=Healing Arts Press | year=1999 | isbn= 978-0-89281-743-6 }} * {{cite book | author=Sellar, Wanda | title=The Directory of Essential Oils | location=Essex | publisher=The C.W. Daniel Company, Ltd. | edition=Reprint | year=2001 | isbn= 978-0-85207-346-9 }} * {{cite book | author=Tisserand, Robert | title=Essential Oil Safety: A Guide for Health Care Professionals | publisher=Churchill Livingstone | year=1995 | isbn= 978-0-443-05260-6 }} * {{cite journal|last1=Rimal|first1=Vishal|last2=Shishodia|first2=Shubham|last3=Srivastava|first3=Prem Kumar|last4=Gupta|first4=Subhadeep|last5=Mallick|first5=Amirul Islam|title=Synthesis and characterization of Indian essential oil Carbon Dots for interdisciplinary applications|journal=Applied Nanoscience|volume=11|issue=4|year=2021|pages=1225–1239|issn=2190-5509|doi=10.1007/s13204-021-01737-3|bibcode=2021ApNan..11.1225R|s2cid=232145772}}

{{DEFAULTSORT:Essential Oil}} Category:Essential oils