Guaifenesin

{{Short description|Expectorant medication}} {{Use dmy dates|date=December 2024}} {{cs1 config|name-list-style=vanc|display-authors=6}} {{Drugbox | verifiedrevid = 458631122 | class = Expectorant | image = Guaifenesin.svg | image_class = skin-invert-image | image2 = Guaifenesin molecule spacefill.png | image_class2 = bg-transparent | width = 222 | chirality = Racemic mixture

| pronounce = {{IPAc-en|ɡ|w|aɪ|ˈ|f|ɛ|n|ᵻ|s|ɪ|n}}<ref>{{cite web| url = https://www.merriam-webster.com/medical/guaifenesin | title = Guaifenesin Definition & Meaning|work = Merriam-Webster}}</ref><br /> {{respell|gwy|FEH|nih|sin}} | tradename = Mucinex, others | Drugs.com = {{drugs.com|monograph|guaifenesin}} | MedlinePlus = a682494 | DailyMedID = Guaifenesin | routes_of_administration = By mouth | ATC_prefix = R05 | ATC_suffix = CA03 | ATC_supplemental = {{ATCvet|M03|BX90}} | legal_NZ = OTC | legal_US = OTC | legal_US_comment = / Rx-only

| bioavailability = | protein_bound = | metabolism = Kidney | metabolites = | elimination_half-life = 1–5 hours<ref name="pmid8218524">{{cite journal|vauthors=Aluri JB, Stavchansky S | title=Determination of guaifenesin in human plasma by liquid chromatography in the presence of pseudoephedrine | journal=J Pharm Biomed Anal | year= 1993 | volume= 11 | issue= 9 | pages= 803–808 | pmid=8218524 | doi= 10.1016/0731-7085(93)80072-9}}</ref> | excretion =  | IUPHAR_ligand = 7617 | CAS_number_Ref = {{cascite|correct|??}} | CAS_number = 93-14-1 | PubChem = 3516 | DrugBank_Ref = {{drugbankcite|correct|drugbank}} | DrugBank = DB00874 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 3396 | UNII_Ref = {{fdacite|correct|FDA}} | UNII = 495W7451VQ | KEGG_Ref = {{keggcite|correct|kegg}} | KEGG = D00337 | ChEMBL_Ref = {{ebicite|correct|EBI}} | ChEMBL = 980 | synonyms = Glyceryl guaiacolate

| IUPAC_name = (''RS'')-3-(2-methoxyphenoxy)propane-1,2-diol | C = 10 | H = 14 | O = 4 | SMILES = O(c1ccccc1OC)CC(O)CO | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/C10H14O4/c1-13-9-4-2-3-5-10(9)14-7-8(12)6-11/h2-5,8,11-12H,6-7H2,1H3 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = HSRJKNPTNIJEKV-UHFFFAOYSA-N }}

'''Guaifenesin''', also known as '''glyceryl guaiacolate''', sold under the brand name '''Mucinex''', among others,<ref name=AHFS2019>{{cite web|title=Guaifenesin Monograph for Professionals|url=https://www.drugs.com/monograph/guaifenesin.html|website=Drugs.com|publisher=American Society of Health-System Pharmacists|access-date=25 March 2019}}</ref> is an expectorant medication taken by mouth and marketed as an aid to eliminate sputum from the respiratory tract. Chemically, it is an ether of guaiacol and glycerine. It may be used in combination with other medications.<ref name="drugs">{{cite web|title=Guaifenesin: Monograph for Professionals|url=https://www.drugs.com/monograph/guaifenesin.html|publisher=Drugs.com, American Society of Health-System Pharmacists|date=23 January 2023|access-date=30 July 2023}}</ref> A 2014 study found that guaifenesin does not affect sputum volume in upper respiratory infections (the upper respiratory system includes most breathing parts above the lungs).<ref name="pmid24003241">{{cite journal | vauthors = Hoffer-Schaefer A, Rozycki HJ, Yopp MA, Rubin BK | title = Guaifenesin has no effect on sputum volume or sputum properties in adolescents and adults with acute respiratory tract infections | journal = Respiratory Care | volume = 59 | issue = 5 | pages = 631–636 | date = May 2014 | pmid = 24003241 | doi = 10.4187/respcare.02640 | doi-access = free }}</ref><ref name="pmid24789023">{{cite journal | vauthors = O'Connell OJ | title = Is extended-release guaifenesin no better than a placebo? | journal = Respir Care | volume = 59 | issue = 5 | pages = 788–9 | date = May 2014 | pmid = 24789023 | doi = 10.4187/respcare.03319 | url = }}</ref> In 2023, it was alleged to work by making airway secretions more liquid.<ref name=drugs/>

Side effects may include dizziness, sleepiness, skin rash, and nausea.<ref name=drugs/> While it has not been properly studied in pregnancy, it appears to be safe.<ref name=Wei2013>{{cite book | vauthors = Weiner CP, Rope K |title=The Complete Guide to Medications During Pregnancy and Breastfeeding: Everything You Need to Know to Make the Best Choices for You and Your Baby |date=2013 |publisher=St. Martin's Press |isbn=978-1-250-03720-6 |page=PT282 |url=https://archive.org/details/completeguidetom0000wein_t9k5 |url-access=registration |language=en}}</ref>

Guaifenesin has been used medically since at least 1933.<ref>{{cite book | vauthors = Riviere JE, Papich MG |title=Veterinary Pharmacology and Therapeutics |date=2013 |publisher=John Wiley & Sons |isbn=978-1-118-68590-7 |page=287 |url=https://books.google.com/books?id=xAPa4WDzAnQC&pg=PA287 }}</ref> It is available as a generic medication and over-the-counter (OTC).<ref name=drugs/><ref name=Wei2013/> In 2023, it was the 291st most commonly prescribed medication in the United States, with more than 500,000 prescriptions.<ref name="Top 300 of 2023">{{cite web | title=The Top 300 of 2023 | url=https://clincalc.com/DrugStats/Top300Drugs.aspx | website=ClinCalc | access-date=17 August 2025 | archive-date=17 August 2025 | archive-url=https://web.archive.org/web/20250817043812/https://clincalc.com/DrugStats/Top300Drugs.aspx | url-status=live }}</ref><ref>{{cite web | title = Guaifenesin Drug Usage Statistics, United States, 2014 - 2023 | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/Guaifenesin | access-date = 17 August 2025 }}</ref> In 2023, the combination dextromethorphan/guaifenesin was the 315th most commonly prescribed medication in the United States, with more than 200,000 prescriptions.<ref>{{cite web | title = Dextromethorphan; Guaifenesin Drug Usage Statistics, United States, 2013 - 2022 | website = ClinCalc | url = https://clincalc.com/DrugStats/Drugs/DextromethorphanGuaifenesin | access-date = 30 August 2024 }}</ref>

==Medical uses== Guaifenesin is used to try to help with coughing up thick mucus. It is sometimes combined with the antitussive (cough suppressant) dextromethorphan, such as in Mucinex DM or Robitussin DM.<ref>{{cite web |url=http://www.webmd.com/drugs/mono-704-GUAIFENESIN%2fDEXTROMETHORPHAN+-+ORAL.aspx?drugid=5508&drugname=Guaifenesin+DM+Oral&source=0 |title=Guaifenesin DM |publisher=WebMD.com }}</ref> It is also combined with ephedrine in Primatene and Bronkaid tablets for symptomatic relief of asthma. Guaifenesin is combined with phenylephrine and paracetamol in certain Lemsip formulations.<ref>{{Cite web |title=Lemsip Max All in One |url=https://www.lemsip.co.uk/collections/lemsip-max-all-in-one |access-date=4 November 2024 |website=LemsipUK |language=en |archive-date=6 November 2024 |archive-url=https://web.archive.org/web/20241106042844/https://www.lemsip.co.uk/collections/lemsip-max-all-in-one |url-status=dead }}</ref>

A Cochrane review identified three clinical trials assessing guaifenesin for the treatment of acute cough, with one finding significant benefit and the other two trials finding that it was not effective.<ref name="pmid25420096">{{cite journal | vauthors = Smith SM, Schroeder K, Fahey T | title = Over-the-counter (OTC) medications for acute cough in children and adults in community settings | journal = Cochrane Database Syst Rev | volume = 2014 | issue = 11 | article-number = CD001831 | date = November 2014 | pmid = 25420096 | pmc = 7061814 | doi = 10.1002/14651858.CD001831.pub5 | url = }}</ref>

==Side effects== Although generally well-tolerated, side effects of guaifenesin may include an allergic reaction (rare), nausea, vomiting, dizziness, or headache.<ref name="drugs-se">{{cite web |title=Guaifenesin Side Effects |url=https://www.drugs.com/sfx/guaifenesin-side-effects.html |publisher=Drugs.com |access-date=30 July 2023 |date=3 July 2023}}</ref><ref name=nlm>{{cite web | title = Guaifenesin | url = https://www.medlineplus.gov/druginfo/meds/a682494.html |publisher = MedlinePlus, United States National Library of Medicine|date=15 January 2022|access-date=30 July 2023}}</ref>

==Pharmacology==

===Mechanism of action=== Guaifenesin might act as an expectorant by increasing the volume and reducing the viscosity of secretions in the trachea and bronchi via stimulation of the gastric mucosa. This stimulation leads to an increased parasympathetic activity in the respiratory tract via the so-called gastro-pulmonary reflex, although some in vitro studies suggested that it might also act directly on the respiratory epithelium.<ref>{{cite journal | vauthors = Albrecht HH, Dicpinigaitis PV, Guenin EP | title = Role of guaifenesin in the management of chronic bronchitis and upper respiratory tract infections | journal = Multidisciplinary Respiratory Medicine | volume = 12 | issue = 1 | article-number = 31 | date = 11 December 2017 | pmid = 29238574 | pmc = 5724298 | doi = 10.1186/s40248-017-0113-4 | doi-access = free }}</ref> This increase in volume and reduction in viscosity aids in the flow of respiratory tract secretions, allowing ciliary movement to carry the loosened secretions upward toward the pharynx.<ref name="e824">{{cite book | vauthors = Gutierrez K | title=Pharmacotherapeutics: clinical reasoning in primary care | publisher=Saunders Elsevier | publication-place=St. Louis, Mo | date=2007 | isbn=978-1-4160-3287-8 | page=}}</ref><ref>{{cite journal | vauthors = Ohar JA, Donohue JF, Spangenthal S | title = The Role of Guaifenesin in the Management of Chronic Mucus Hypersecretion Associated with Stable Chronic Bronchitis: A Comprehensive Review | language = en-US | journal = Chronic Obstructive Pulmonary Diseases | volume = 6 | issue = 4 | pages = 341–349 | date = October 2019 | doi = 10.15326/jcopdf.6.4.2019.0139 | pmid = 31647856 | url = https://journal.copdfoundation.org/jcopdf/id/1248/The-Role-of-Guaifenesin-in-the-Management-of-Chronic-Mucus-Hypersecretion-Associated-with-Stable-Chronic-Bronchitis-A-Comprehensive-Review | pmc = 7006698 }}</ref> Thus, guaifenesin may increase the efficiency of the cough reflex and facilitate the removal of the secretions. Additionally, guaifenesin has a demonstrated central antitussive effect.<ref>{{cite journal | vauthors = Ohar JA, Donohue JF, Spangenthal S | title = The Role of Guaifenesin in the Management of Chronic Mucus Hypersecretion Associated with Stable Chronic Bronchitis: A Comprehensive Review | language = en-US | journal = Chronic Obstructive Pulmonary Diseases | volume = 6 | issue = 4 | pages = 341–349 | date = October 2019 | doi = 10.15326/jcopdf.6.4.2019.0139 | pmid = 31647856 | url = https://journal.copdfoundation.org/jcopdf/id/1248/The-Role-of-Guaifenesin-in-the-Management-of-Chronic-Mucus-Hypersecretion-Associated-with-Stable-Chronic-Bronchitis-A-Comprehensive-Review | pmc = 7006698 }}</ref>

==History== Similar medicines derived from the guaiac tree were used as a generic remedy by American indigenous peoples when explorers reached North America in the 16th century. The Spanish encountered guaiacum wood "when they conquered Santo Domingo; it was soon brought back to Europe, where it acquired an immense reputation in the sixteenth century as a cure for syphilis and certain other diseases..."<ref name="Wallis1955">{{cite book | vauthors = Wallis TE |title=Textbook of Pharmacognosy|url=https://archive.org/details/textbookofpharma00wall |url-access=registration |year=1955}}</ref>

The 1955 edition of the ''Textbook of Pharmacognosy'' states: "Guaiacum has a local stimulant action which is sometimes useful in sore throat. The resin is used in chronic gout and rheumatism, whilst the wood is an ingredient in the compound concentrated solution of sarsaparilla, which was formerly much used as an alterative in syphilis."<ref name="Wallis1955" />

In the US, guaifenesin was first approved by the Food and Drug Administration (FDA) in 1952. Although previously deemed "Generally Regarded as Safe" in its original approval, the drug received a New Drug Application for the extended-release version, which received approval on 12 July 2002.<ref>{{cite web | title=Drug Approval Package: Mucinex (Guaifenesin) NDA #21-282 | website=accessdata.fda.gov | date=25 November 2002 | url=https://www.accessdata.fda.gov/drugsatfda_docs/nda/2002/21-282_Mucinex.cfm | archive-url=https://web.archive.org/web/20150425040951/http://www.accessdata.fda.gov/drugsatfda_docs/nda/2002/21-282_Mucinex.cfm | archive-date=25 April 2015 | access-date=26 October 2022}}</ref> Because of this, the FDA then issued letters to other manufacturers of ''timed-release'' guaifenesin to stop marketing their unapproved versions, leaving Adams Respiratory Therapeutics in control of the market. In 2007, Adams was acquired by Reckitt Benckiser.<ref>{{cite web |url=http://www.rb.com/site/RKBR/Templates/MediaInvestorsGeneral2.aspx?pageid=262&cc=GB |title=Announcements RB Press release - 10/12/2007 |access-date=16 November 2010 |archive-url=https://web.archive.org/web/20110715161154/http://www.rb.com/site/RKBR/Templates/MediaInvestorsGeneral2.aspx?pageid=262&cc=GB |archive-date=15 July 2011 }}</ref><ref>{{cite news | vauthors = Goldstein J |title=FDA Bumps Phlegm-Fighters From Market |url=https://blogs.wsj.com/health/2007/05/25/fda-bumps-phlegm-fighters-from-market/ |date=25 May 2007 |newspaper=The Wall Street Journal |access-date=16 November 2010}}</ref> The drug is now sold over-the-counter by many companies, alone and in combination.<ref>{{Cite web|title=Guaifenesin (Oral Route) Description and Brand Names |url=https://www.mayoclinic.org/drugs-supplements/guaifenesin-oral-route/description/drg-20068720|access-date=27 July 2021|website=Mayo Clinic }}</ref>

==Veterinary use== Guaifenesin's neurological properties first became known in the late 1940s. Guaifenesin is a centrally acting muscle relaxant used routinely in large-animal veterinary surgery. Guaifenesin is used in combination with, for example, ketamine, since guaifenesin does not provide analgesia or produce unconsciousness.<ref>{{cite book |title=Lumb and Jones' Veterinary Anesthesia and Analgesia |date=2007 |publisher=Blackwell Publishing |veditors=Tranquilli WJ, Thurmon JC, Grimm KA |edition=2nd |chapter=Centrally Acting Muscle Relaxants}}</ref><ref name="horse">{{cite journal |vauthors=Valverde A |date=Apr 2013 |title=Balanced anesthesia and constant-rate infusions in horses |journal=Vet Clin North Am Equine Pract |volume=29 |issue=1 |pages=89–122 |doi=10.1016/j.cveq.2012.11.004 |pmid=23498047}}</ref> In horses, the drug's biological half-life is 77 minutes. Premedication with xylazine (1.1 mg/kg) can reduce the dose required from 163 mg/kg (in geldings) to just 88 mg/kg.<ref name="horse" />

== Society and culture == === Brand names === Guaifenesin is taken by mouth,<ref name=drugs/> and is supplied as a tablet, a capsule, an extended-release (long-acting) tablet, dissolving granules, and a syrup.<ref name=nlm/> It is available under many brand names, as either the sole active ingredient or part of a combination drug.<ref name=nlm/> Drugs combined with guaifenesin in over-the-counter preparations include the cough-suppressant dextromethorphan, analgesics such as paracetamol/acetaminophen, and decongestants such as ephedrine, pseudoephedrine, or phenylephrine.<ref name=nlm/>

=== Economics === In 2014, sales of guaifenesin were estimated to be approximately $135 million per year in the United States.<ref name="pmid24789023" />

==See also== *Guaifenesin protocol

==References== {{Reflist}}

==External links== * {{cite web | title=F.D.A. Study Worries Makers of Drugs | website=The New York Times | date=20 October 1981 | url=https://www.nytimes.com/1981/10/20/business/fda-study-worries-makers-of-drugs.html }}

Category:Drugs with unknown mechanisms of action Category:Expectorants Category:Catechol ethers Category:Wikipedia medicine articles ready to translate Category:Glycerol ethers Category:2-Methoxyphenyl compounds Category:Over-the-counter drugs in the United States