Functional somatic syndrome

{{More medical citations needed|reason=Primary sources or excessively dated|date=July 2025}} {{cs1 config|name-list-style=vanc|display-authors=6}} {{Infobox medical condition | name = Functional somatic syndrome | synonyms = | field = Psychiatry, psychosomatic medicine, psychoneuroendocrinoimmunology | differential = Organic/medical illness, primary psychiatric disorders (depression/anxiety with somatic features; psychotic disorders with somatic delusions), functional neurological disorder, somatic symptom disorder, mass psychogenic illness, illness anxiety disorder, Munchausen's and Munchausen's by proxy, deconditioning, malingering | treatment = *Psychological therapies ** Cognitive-behavioural therapy ** Psychodynamic Psychotherapy ** Psychoeducation ** relaxation therapy * Physical therapies ** Exercise (sports) ** Supervised aerobic training ** Behavioral activation therapy * Other non-pharmacological interventions<ref name="Non-pharmacological interventions f">{{cite journal | title=Non-pharmacological interventions for somatoform disorders and medically unexplained physical symptoms (MUPS) in adults | journal=Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD011142 | doi=10.1002/14651858.CD011142.pub2 | pmid=25362239 | pmc=10984143 | vauthors = Van Dessel N, Den Boeft M, Van Der Wouden JC, Kleinstäuber M, Leone SS, Terluin B, Numans ME, Van Der Horst HE, Van Marwijk H }}</ref> | medication = *Primarily non-pharmacological treatments<ref>{{cite journal | title=Management of functional somatic syndromes | journal=Lancet | date=2007 | volume=369 | issue=9565 | pages=946–955 | doi=10.1016/S0140-6736(07)60159-7 | pmid=17368156 | vauthors = Henningsen P, Zipfel S, Herzog W }}</ref><ref name="Non-pharmacological interventions f">{{cite journal | title=Non-pharmacological interventions for somatoform disorders and medically unexplained physical symptoms (MUPS) in adults | journal=Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD011142 | doi=10.1002/14651858.CD011142.pub2 | pmid=25362239 | pmc=10984143 | vauthors = Van Dessel N, Den Boeft M, Van Der Wouden JC, Kleinstäuber M, Leone SS, Terluin B, Numans ME, Van Der Horst HE, Van Marwijk H }}</ref> ** SSRIs<ref name="Pharmacological interventions for s">{{cite journal | title=Pharmacological interventions for somatoform disorders in adults | journal=The Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD010628 | doi=10.1002/14651858.CD010628.pub2 | pmid=25379990 | pmc=11023023 | vauthors = Kleinstäuber M, Witthöft M, Steffanowski A, Van Marwijk H, Hiller W, Lambert MJ }}</ref> ** SNRIs<ref name="Pharmacological interventions for s">{{cite journal | title=Pharmacological interventions for somatoform disorders in adults | journal=The Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD010628 | doi=10.1002/14651858.CD010628.pub2 | pmid=25379990 | pmc=11023023 | vauthors = Kleinstäuber M, Witthöft M, Steffanowski A, Van Marwijk H, Hiller W, Lambert MJ }}</ref> ** Tricyclic Antidepressants<ref name="Pharmacological interventions for s">{{cite journal | title=Pharmacological interventions for somatoform disorders in adults | journal=The Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD010628 | doi=10.1002/14651858.CD010628.pub2 | pmid=25379990 | pmc=11023023 | vauthors = Kleinstäuber M, Witthöft M, Steffanowski A, Van Marwijk H, Hiller W, Lambert MJ }}</ref> ** Gabapentinoids (Pregabalin, Gabapentin)<ref name="Pharmacological interventions for s">{{cite journal | title=Pharmacological interventions for somatoform disorders in adults | journal=The Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD010628 | doi=10.1002/14651858.CD010628.pub2 | pmid=25379990 | pmc=11023023 | vauthors = Kleinstäuber M, Witthöft M, Steffanowski A, Van Marwijk H, Hiller W, Lambert MJ }}</ref> ** Low-dose Antipsychotics<ref name="Pharmacological interventions for s">{{cite journal | title=Pharmacological interventions for somatoform disorders in adults | journal=The Cochrane Database of Systematic Reviews | date=2014 | issue=11 | article-number=CD010628 | doi=10.1002/14651858.CD010628.pub2 | pmid=25379990 | pmc=11023023 | vauthors = Kleinstäuber M, Witthöft M, Steffanowski A, Van Marwijk H, Hiller W, Lambert MJ }}</ref> | prognosis = | frequency = | deaths = }} '''Functional somatic syndrome''' ('''FSS''') (sometimes termed "non-specific physical disorders") refers to a cluster of chronic conditions, characterized by persistent physical symptoms without demonstrable structural or organic disease despite extensive medical testing.<ref name="auto1" />

Contemporary theories describe the aetiology as involing a dysregulation in the brain-body signaling, which includes negative emotional states pathologically activating somatosensory and nociceptive circuits, generating genuine physical sensations through central sensitization, maladaptive stress response systems and learned neuroplastic rewiring, with symptoms resulting from complex interactions between the autonomic nervous system, hypothalamo-pituitary axis and possibly the immune system, rather than from peripheral tissue damage.<ref>{{Cite journal |last1=Bogaerts |first1=Katleen |last2=Van Den Houte |first2=Maaike |last3=Jongen |first3=Daniëlle |last4=Ly |first4=Huynh Giao |last5=Coppens |first5=Eline |last6=Schruers |first6=Koen |last7=Van Diest |first7=Ilse |last8=Jan |first8=Tack |last9=Van Wambeke |first9=Peter |last10=Petre |first10=Bogdan |last11=Kragel |first11=Philip A. |last12=Lindquist |first12=Martin A. |last13=Wager |first13=Tor D. |last14=Van Oudenhove |first14=Lukas |last15=Van den Bergh |first15=Omer |date=2023-08-21 |title=Brain mediators of negative affect-induced physical symptom reporting in patients with functional somatic syndromes |journal=Translational Psychiatry |language=en |volume=13 |issue=1 |page=285 |doi=10.1038/s41398-023-02567-3 |pmid=37604880 |pmc=10442365 |issn=2158-3188}}</ref><ref>{{Cite journal |last1=Bourke |first1=Julius H. |last2=Langford |first2=Richard M. |last3=White |first3=Peter D. |date=March 2015 |title=The common link between functional somatic syndromes may be central sensitisation |journal=Journal of Psychosomatic Research |volume=78 |issue=3 |pages=228–236 |doi=10.1016/j.jpsychores.2015.01.003 |issn=1879-1360 |pmid=25598410}}</ref><ref>{{Cite journal |last1=Barsky |first1=Arthur J. |last2=Borus |first2=Jonathan F. |date=June 1999 |title=Functional Somatic Syndromes |url=https://www.acpjournals.org/doi/10.7326/0003-4819-130-11-199906010-00016 |journal=Annals of Internal Medicine |volume=130 |issue=11 |pages=910–921 |doi=10.7326/0003-4819-130-11-199906010-00016 |pmid=10375340 |issn=0003-4819|url-access=subscription }}</ref><ref>{{Cite journal |last1=Burton |first1=Christopher |last2=Fink |first2=Per |last3=Henningsen |first3=Peter |last4=Löwe |first4=Bernd |last5=Rief |first5=Winfried |last6=EURONET-SOMA Group |date=2020-03-03 |title=Functional somatic disorders: discussion paper for a new common classification for research and clinical use |journal=BMC Medicine |volume=18 |issue=1 |page=34 |doi=10.1186/s12916-020-1505-4 |doi-access=free |issn=1741-7015 |pmc=7052963 |pmid=32122350}}</ref>

Fibromyalgia, chronic fatigue syndrome (now called ME/CFS) and irritable bowel syndrome are some of the most common disorders that have been described as FSS conditions,<ref>{{Cite journal |last1=Häuser |first1=Winfried |last2=Eich |first2=Wolfgang |last3=Herrmann |first3=Markus |last4=Nutzinger |first4=Detlev O. |last5=Schiltenwolf |first5=Marcus |last6=Henningsen |first6=Peter |date=June 2009 |title=Fibromyalgia syndrome: classification, diagnosis, and treatment |journal=Deutsches Arzteblatt International |volume=106 |issue=23 |pages=383–391 |doi=10.3238/arztebl.2009.0383 |issn=1866-0452 |pmc=2712241 |pmid=19623319}}</ref><ref>{{Cite journal |last1=Lacourt |first1=Tamara |last2=Houtveen |first2=Jan |last3=van Doornen |first3=Lorenz |date=2013-01-01 |title="Functional somatic syndromes, one or many?": An answer by cluster analysis |url=https://www.sciencedirect.com/science/article/pii/S0022399912002620 |journal=Journal of Psychosomatic Research |volume=74 |issue=1 |pages=6–11 |doi=10.1016/j.jpsychores.2012.09.013 |pmid=23272982 |issn=0022-3999|url-access=subscription }}</ref><ref>{{Cite journal |last1=Hausteiner-Wiehle |first1=Constanze |last2=Henningsen |first2=Peter |date=2014-05-28 |title=Irritable bowel syndrome: relations with functional, mental, and somatoform disorders |journal=World Journal of Gastroenterology |volume=20 |issue=20 |pages=6024–6030 |doi=10.3748/wjg.v20.i20.6024 |doi-access=free |issn=2219-2840 |pmc=4033442 |pmid=24876725}}</ref> although the classification of ME/CFS as an FSS has been increasingly called into question in the recent years.<ref>{{Cite journal |last1=Thoma |first1=Manuel |last2=Froehlich |first2=Laura |last3=Hattesohl |first3=Daniel B. R. |last4=Quante |first4=Sonja |last5=Jason |first5=Leonard A. |last6=Scheibenbogen |first6=Carmen |date=2023-12-31 |title=Why the Psychosomatic View on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Is Inconsistent with Current Evidence and Harmful to Patients |journal=Medicina (Kaunas, Lithuania) |volume=60 |issue=1 |page=83 |doi=10.3390/medicina60010083 |doi-access=free |issn=1648-9144 |pmc=10819994 |pmid=38256344}}</ref><ref>{{Cite book |last1=Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome |url=http://www.ncbi.nlm.nih.gov/books/NBK274235/ |title=Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness |last2=Board on the Health of Select Populations |last3=Institute of Medicine |date=2015 |publisher=National Academies Press (US) |isbn=978-0-309-31689-7 |series=The National Academies Collection: Reports funded by National Institutes of Health |location=Washington (DC) |pmid=25695122}}</ref><ref>{{Cite journal |last=Komaroff |first=Anthony L. |date=2019-08-13 |title=Advances in Understanding the Pathophysiology of Chronic Fatigue Syndrome |journal=JAMA |volume=322 |issue=6 |pages=499–500 |doi=10.1001/jama.2019.8312 |issn=1538-3598 |pmid=31276153}}</ref> Functional somatic syndromes are very common, although specific criteria differ, they are estimated to affect about anywhere from 4% to 16% of the general population.<ref>{{Cite journal |last1=Madsen |first1=Michael M. |last2=Trolle |first2=Christian |last3=Fynne |first3=Lotte V. |last4=Colombo |first4=Michele |last5=Pedersen |first5=Rasmus L. |last6=Sørensen |first6=Vibeke N. |last7=Christensen |first7=Susan R. |last8=Fink |first8=Per |last9=Gormsen |first9=Lise K. |date=November 2025 |title=Early identification of functional somatic disorders in an internal medicine diagnostic clinic: The DISTRESS trial |journal=Contemporary Clinical Trials |language=en |volume=158 |article-number=108082 |doi=10.1016/j.cct.2025.108082 |pmid=40972891 |doi-access=free }}</ref><ref>{{Cite journal |last1=Rometsch |first1=Caroline |last2=Mansueto |first2=Giovanni |last3=Maas Genannt Bermpohl |first3=Frederic |last4=Martin |first4=Alexandra |last5=Cosci |first5=Fiammetta |date=June 2024 |title=Prevalence of functional disorders across Europe: a systematic review and meta-analysis |journal=European Journal of Epidemiology |language=en |volume=39 |issue=6 |pages=571–586 |doi=10.1007/s10654-024-01109-5 |issn=0393-2990 |pmc=11249491 |pmid=38551715}}</ref><ref>{{Cite journal |last1=Petersen |first1=Marie Weinreich |last2=Schröder |first2=Andreas |last3=Jørgensen |first3=Torben |last4=Ørnbøl |first4=Eva |last5=Dantoft |first5=Thomas Meinertz |last6=Eliasen |first6=Marie |last7=Carstensen |first7=Tina Wisbech |last8=Falgaard Eplov |first8=Lene |last9=Fink |first9=Per |date=July 2020 |title=Prevalence of functional somatic syndromes and bodily distress syndrome in the Danish population: the DanFunD study |journal=Scandinavian Journal of Public Health |volume=48 |issue=5 |pages=567–576 |doi=10.1177/1403494819868592 |issn=1651-1905 |pmid=31409218}}</ref><ref>{{Cite journal |last1=Rometsch |first1=Caroline |last2=Cosci |first2=Fiammetta |last3=Martin |first3=Alexandra |date=July 2024 |title=Prävalenz von chronischem Schmerz und funktionellen somatischen Syndromen in Deutschland: Systematisches Review und Metaanalyse |url=https://cris.maastrichtuniversity.nl/en/publications/pr%C3%A4valenz-von-chronischem-schmerz-und-funktionellen-somatischen-s/ |journal=Psychotherapie |volume=69 |issue=4 |pages=217–230 |doi=10.1007/s00278-024-00734-5 |issn=2731-7161}}</ref>

==Definition and Terminology== FSS refers to disturbances in bodily functioning where aetiology is unknown.<ref>{{cite journal | doi=10.1038/s41598-020-66685-4 | title=Comorbidities of Patients with Functional Somatic Syndromes Before, During and After First Diagnosis: A Population-based Study using Bavarian Routine Data | date=2020 | journal=Scientific Reports | volume=10 | issue=1 | article-number=9810 | pmid=32555301 | pmc=7299983 | bibcode=2020NatSR..10.9810D | vauthors = Donnachie E, Schneider A, Enck P }}</ref> The term 'functional somatic disorders' (FSD) was proposed in 2020.<ref>{{cite journal | author6=on behalf of the EURONET-SOMA Group | title=Functional somatic disorders: Discussion paper for a new common classification for research and clinical use | journal=BMC Medicine | date=2020 | volume=18 | issue=1 | page=34 | doi=10.1186/s12916-020-1505-4 | doi-access=free | pmid=32122350 | pmc=7052963 | vauthors = Burton C, Fink P, Henningsen P, Löwe B, Rief W }}</ref>

===Related terms=== "Medically unexplained physical symptoms" only include symptoms where no explanation is found at all, but not poorly understood syndromes like fibromyalgia or IBS. These symptoms can sometimes be worsened in the presence of mental health problems.<ref name="auto3">{{Cite web|url=https://www.nhs.uk/conditions/medically-unexplained-symptoms/|title=Medically unexplained symptoms|date=October 15, 2025|website=nhs.uk}}</ref>

"Persistent physical symptoms"<ref>{{Cite journal|url=https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00623-8/fulltext|title=Persistent physical symptoms: definition, genesis, and management|first1=Bernd|last1=Löwe|first2=Anne|last2=Toussaint|first3=Judith G. M.|last3=Rosmalen|first4=Wei-Lieh|last4=Huang|first5=Christopher|last5=Burton|first6=Angelika|last6=Weigel|first7=James L.|last7=Levenson|first8=Peter|last8=Henningsen|date=June 15, 2024|journal=The Lancet|volume=403|issue=10444|pages=2649–2662|via=www.thelancet.com|doi=10.1016/S0140-6736(24)00623-8|pmid=38879263|hdl=11370/4dab9091-5fd6-47d9-84f8-cbfb2d7b4f76|hdl-access=free}}</ref> includes FSS situations but also situations where persistent physical symptoms are caused by a known illness, such as arthritis.

In "somatic symptom disorder" chronic physical symptoms, which may or may not be linked to a known illness, coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those symptoms. In FSS these features are not present.

==Classification== Being an umbrella term, the disorder is not encoded in the ICD-11, rather its separate manifestations have specific codes there. Proposals for classifications have been made.<ref name="ReferenceA">{{Cite journal|author6=on behalf of the EURONET-SOMA Group |title=Functional somatic disorders: discussion paper for a new common classification for research and clinical use - PMC |journal=BMC Medicine |date=2020 |volume=18 |issue=1 |page=34 |doi=10.1186/s12916-020-1505-4 |doi-access=free |pmid=32122350 |pmc=7052963 | vauthors = Burton C, Fink P, Henningsen P, Löwe B, Rief W }}</ref>

==Signs and symptoms== Functional somatic syndromes are characterized by ambiguous, non-specific symptoms that appear in otherwise-healthy people. Overlap in symptomology exists across diagnoses, including gastrointestinal issues, pain, fatigue, cognitive difficulties, and sleep difficulties. Some have proposed to group symptoms into clusters<ref>{{cite journal | vauthors = Fink P, Schröder A | title = One single diagnosis, bodily distress syndrome, succeeded to capture 10 diagnostic categories of functional somatic syndromes and somatoform disorders | journal = Journal of Psychosomatic Research | volume = 68 | issue = 5 | pages = 415–426 | date = May 2010 | pmid = 20403500 | doi = 10.1016/j.jpsychores.2010.02.004 }}</ref><ref>{{cite journal | vauthors = Lacourt T, Houtveen J, van Doornen L | title = "Functional somatic syndromes, one or many?" An answer by cluster analysis | journal = Journal of Psychosomatic Research | volume = 74 | issue = 1 | pages = 6–11 | date = January 2013 | pmid = 23272982 | doi = 10.1016/j.jpsychores.2012.09.013 | doi-access = free }}</ref> or into one general functional somatic disorder given the finding of correlations between symptoms and underlying etiologies.<ref>{{cite journal | vauthors = Wessely S, White PD | title = There is only one functional somatic syndrome | journal = The British Journal of Psychiatry | volume = 185 | issue = 2 | pages = 95–96 | date = August 2004 | pmid = 15286058 | doi = 10.1192/bjp.185.2.95 | doi-access = free }}</ref>

==FSS conditions==

The following conditions are often considered to be representations of the functional somatic syndrome: *Myalgic encephalomyelitis/chronic fatigue syndrome<ref>{{Cite journal |last1=Fischer |first1=Susanne |last2=Kleinstäuber |first2=Maria |last3=Fiori |first3=Laura M. |last4=Turecki |first4=Gustavo |last5=Wagner |first5=Julia |last6=von Känel |first6=Roland |date=2023 |title=DNA Methylation Signatures of Functional Somatic Syndromes: Systematic Review |journal=Psychosomatic Medicine |language=en |volume=85 |issue=8 |pages=672–681 |doi=10.1097/PSY.0000000000001237 |issn=1534-7796|doi-access=free |pmid=37531610 }}</ref> *Fibromyalgia<ref name=":3" /> *Mold allergy *Temporomandibular disorder *Irritable bowel syndrome<ref name=":3" /><ref name="trauma">{{cite journal | vauthors = Afari N, Ahumada SM, Wright LJ, Mostoufi S, Golnari G, Reis V, Cuneo JG | title = Psychological trauma and functional somatic syndromes: a systematic review and meta-analysis | journal = Psychosomatic Medicine | volume = 76 | issue = 1 | pages = 2–11 | date = January 2014 | pmid = 24336429 | pmc = 3894419 | doi = 10.1097/PSY.0000000000000010 }}</ref> *Electromagnetic hypersensitivity *Lower back pain *Tension headache *Atypical face pain *Insomnia *Long-haul COVID<ref>{{Cite journal |last1=Joffe |first1=Ari R |last2=Elliott |first2=April |date=2023-01-01 |title=Long COVID as a functional somatic symptom disorder caused by abnormally precise prior expectations during Bayesian perceptual processing: A new hypothesis and implications for pandemic response |journal=Sage Open Medicine |language=EN |volume=11 |doi=10.1177/20503121231194400 |issn=2050-3121 |pmc=10467233 |pmid=37655303 |article-number=20503121231194400}}</ref> *Palpitation *Dyspepsia *Dizziness<ref name="mayou">{{cite journal | vauthors = Mayou R, Farmer A | title = ABC of psychological medicine: Functional somatic symptoms and syndromes | journal = BMJ | volume = 325 | issue = 7358 | pages = 265–268 | date = August 2002 | pmid = 12153926 | pmc = 1123778 | doi = 10.1136/bmj.325.7358.265 }}</ref> * Unevidenced claims of food allergies<ref name=":3" /> * Gulf War syndrome<ref name=":3" /> * Undemonstrable hypoglycaemia (with symptoms appearing when the blood sugar is normal)<ref name=":3" /> * Chronic Lyme disease<ref name=":3" /> * Multiple chemical sensitivity<ref name=":3">{{Citation |title=2.2 The Putative Disappearance of Somatic Manifestations of Hysteria |date=2022-12-31 |work=From Photography to fMRI |pages=219–237 |publisher=transcript Verlag |doi=10.1515/9783839461761-009 |isbn=978-3-8394-6176-1 |quote=In the late 1990s, it became a matter of heated debate if hysteria's nosological successors were conceptually and diagnostically distinguishable from a range of possibly related clinical conditions that were equally characterised by the lack of any demonstrable physical abnormality. Jointly referred to as functional somatic syndromes, these conditions include multiple chemical sensitivity, sick building syndrome, chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, chronic whiplash, chronic Lyme disease, the Gulf War syndrome, food allergies, hypoglycaemia. To this date, the delineation between present-day forms of hysteria and other functional somatic syndromes remains unresolved.|doi-access=free }}</ref> * Food intolerance (when not a true allergy)<ref>{{Cite journal |last1=Manu |first1=P. |last2=Matthews |first2=D. A. |last3=Lane |first3=T. J. |date=March 1993 |title=Food intolerance in patients with chronic fatigue |journal=The International Journal of Eating Disorders |volume=13 |issue=2 |pages=203–209 |doi=10.1002/1098-108x(199303)13:2<203::aid-eat2260130208>3.0.co;2-u |issn=0276-3478 |pmid=8477289}}</ref><ref>{{Cite journal |last1=Yantcheva |first1=B. |last2=Mohr |first2=P. |last3=Martin |first3=M. |date=2016-12-31 |title=Food intolerance â€" evidence for functional somatic syndrome? |url=https://ehps.net/ehp/index.php/contents/article/view/2235 |journal=European Health Psychologist |language=en |page=882 |issn=2225-6962}}</ref> * Sick building syndrome<ref name=":3" /> * Chronic whiplash<ref name=":3" />

===Overlap of FSS conditions=== A considerable overlap of symptoms exists between the FSS diagnoses, with high rates of comorbidity between them. For example, the prevalence of comorbid FSS diagnoses ranges from 20% to 70%, while comorbid affective disorders with a fibromyalgia diagnosis ranges from 20% to 80%.<ref>{{cite journal | vauthors = Häuser W, Kosseva M, Üceyler N, Klose P, Sommer C | title = Emotional, physical, and sexual abuse in fibromyalgia syndrome: a systematic review with meta-analysis | journal = Arthritis Care & Research | volume = 63 | issue = 6 | pages = 808–820 | date = June 2011 | pmid = 20722042 | doi = 10.1002/acr.20328 | doi-access = free }}</ref>

==Prevalence== Studies have found prevalence in the general population of having at least one FSS of 16.3% (n = 9656),<ref>{{Cite journal|title=Prevalence of functional somatic syndromes and bodily distress syndrome in the Danish population: the DanFunD study|first1=Marie Weinreich|last1=Petersen|first2=Andreas|last2=Schröder|first3=Torben|last3=Jørgensen|first4=Eva|last4=Ørnbøl|first5=Thomas Meinertz|last5=Dantoft|first6=Marie|last6=Eliasen|first7=Tina Wisbech|last7=Carstensen|first8=Lene|last8=Falgaard Eplov|first9=Per|last9=Fink|date=July 1, 2020|journal=Scandinavian Journal of Public Health|volume=48|issue=5|pages=567–576|doi=10.1177/1403494819868592|pmid=31409218}}</ref> and 9.3% (n = 3054).<ref name="auto">{{Cite journal|title=Prevalence, overlap, and predictors of functional somatic syndromes in a student sample|first1=Susanne|last1=Fischer|first2=Jens|last2=Gaab|first3=Ulrike|last3=Ehlert|first4=Urs M.|last4=Nater|date=June 1, 2013|journal=International Journal of Behavioral Medicine|volume=20|issue=2|pages=184–193|doi=10.1007/s12529-012-9266-x|pmid=23055025}}</ref>

Some 10% of the general population, and around 33% of adult patients in clinical populations, suffer from functional somatic symptoms.<ref>{{Cite journal|title=Functional Somatic Symptoms|first1=Casper|last1=Roenneberg|first2=Heribert|last2=Sattel|first3=Rainer|last3=Schaefert|first4=Peter|last4=Henningsen|first5=Constanze|last5=Hausteiner-Wiehle|date=Aug 9, 2019|journal=Deutsches Ärzteblatt International|volume=116|issue=33–34|pages=553–560|doi=10.3238/arztebl.2019.0553|pmid=31554544|pmc=6794707}}</ref>

==Potential causes==

A mixture of physical and psychological factors may predict FSS.<ref name="auto1"/><ref name="ReferenceA"/>

=== Psychological factors === Low-quality evidence suggests that patients with somatic syndromes, such as fibromyalgia and irritable bowel syndrome, tend to have a more frequent history of both physical and sexual abuse prior to the onset of their physiological symptoms. Additionally, patients show higher rates of previous emotional abuse, emotional neglect, and physical neglect when compared to the general population.<ref>{{cite journal | vauthors = Yavne Y, Amital D, Watad A, Tiosano S, Amital H | title = A systematic review of precipitating physical and psychological traumatic events in the development of fibromyalgia | journal = Seminars in Arthritis and Rheumatism | volume = 48 | issue = 1 | pages = 121–133 | date = August 2018 | pmid = 29428291 | doi = 10.1016/j.semarthrit.2017.12.011 | s2cid = 205143853 }}</ref>

Attentional bias has been posited as the psychological mechanism by which trauma and somatic symptoms are tied.<ref name=":1">{{cite journal | vauthors = Golding JM | title = Sexual assault history and physical health in randomly selected Los Angeles women | journal = Health Psychology | volume = 13 | issue = 2 | pages = 130–138 | date = March 1994 | pmid = 8020456 | doi = 10.1037/0278-6133.13.2.130 }}</ref><ref name=":2">{{Cite journal| vauthors = Carleton RN, Duranceau S, McMillan KA, Asmundson GJ |date=April 2018|title=Trauma, Pain, and Psychological Distress|journal=Journal of Psychophysiology|volume=32|issue=2|pages=75–84|doi=10.1027/0269-8803/a000184|s2cid=151333609 |issn=0269-8803}}</ref>{{Unreliable medical source|date=July 2025}} Attentional bias refers to the idea that traumatic events can cause individuals to become more attuned to their bodily functions, thus intensifying the perception of pain, fatigue, and other common somatic symptoms.<ref name=":2" />{{Unreliable medical source|date=July 2025}} The initial traumatic event is interpreted as a threat to the body, and therefore the stress response of the body takes on a new, heightened awareness to any potential subsequent threats. This attentional bias leads to health anxiety, wherein the patient becomes increasingly concerned that common somatic symptoms are related to a physical disease or injury, and therefore, another potential bodily threat.<ref name=":1" />{{Unreliable medical source|date=July 2025}} An initial perception of lost control can further intensify attentional bias; sense of control is negatively associated with symptom reporting, suggesting that somatic symptoms are more closely monitored when psychologically recovering from an incident of lost control.<ref>{{Cite book| vauthors = Pennebaker JW |date=1982|title=The Psychology of Physical Symptoms|doi=10.1007/978-1-4613-8196-9|isbn=978-1-4613-8198-3}}</ref>{{Unreliable medical source|date=July 2025}} Functional somatic syndromes are thought to be a result of conditioned hyperarousal following a trauma; victims are conditioned to respond more sensitively to the somatic symptoms following a trauma by their attention to and reinforcement of the symptom existence. This feedback loop is similar to that of panic disorder, in which fear of a subsequent panic attack causes an increased hyper-vigilance towards, and exacerbation of, physiological symptoms, such as heart palpitations, dizziness, and breathlessness.<ref>{{Cite journal| vauthors = Antony MM, Brown TA, Craske MG, Barlow DH, Mitchell WB, Meadows EA |date=September 1995|title=Accuracy of heartbeat perception in panic disorder, social phobia, and nonanxious subjects|journal=Journal of Anxiety Disorders|volume=9|issue=5|pages=355–371|doi=10.1016/0887-6185(95)00017-i|issn=0887-6185}}</ref>{{Unreliable medical source|date=July 2025}}

=== Biological factors === One hypothesis implicates the hypothalamic–pituitary–adrenal axis (HPA axis) in the manifestation of somatic symptoms following trauma. The HPA axis plays a major role in moderating the body's stress response to both emotional and physical pain, relating to both the experience of psychological symptoms prevalent following trauma as well as the physiological symptoms prevalent in FSS conditions.<ref>{{cite book | vauthors = Bryant RA |chapter=Psychological Interventions for Trauma Exposure and PTSD|date=2011-07-15|pages=171–202|publisher=John Wiley & Sons, Ltd |isbn=978-1-119-99847-1 |doi=10.1002/9781119998471.ch5 |title=Post-Traumatic Stress Disorder }}</ref> When an individual experiences a traumatic event, the HPA axis causes the increased release of cortisol, activating the sympathetic nervous system and causing negative feedback to be sent to the hypothalamus and pituitary gland. In people who have experienced major trauma, this reaction can become dysfunctional and can cause a chronic decrease in cortisol production, though the rates of this decrease in cortisol levels vary across different types and frequencies of trauma.<ref>{{cite journal | vauthors = Weber DA, Reynolds CR | title = Clinical perspectives on neurobiological effects of psychological trauma | journal = Neuropsychology Review | volume = 14 | issue = 2 | pages = 115–129 | date = June 2004 | pmid = 15264712 | doi = 10.1023/b:nerv.0000028082.13778.14 | s2cid = 24172922 }}</ref>

==Diagnosis== Diagnosis of a FSS is usually a diagnosis of exclusion, where physicians rule out other disorders that could explain the dysfunctions being experienced.<ref>{{Cite journal|title=Functional somatic syndromes: asking about exclusionary medical conditions results in decreased prevalence and overlap rates|first1=Susanne|last1=Fischer|first2=Urs M.|last2=Nater|date=October 4, 2014|journal=BMC Public Health|volume=14|article-number=1034|doi=10.1186/1471-2458-14-1034|doi-access=free |pmid=25280494|pmc=4286915}}</ref> The DDx is often complex and involves factual organic pathology, as well as a number of psychiatric disorders, including somatic delusions, primary mood/anxiety disorders with somatic manifestations, somatic symptom disorder, illness anxiety disorder, functional neurological disorder, factitious disorder, and malingering, as well as primary deconditioning.

==Management and Treatment== Psychological interventions are considered the primary treatment for functional somatic syndromes, with cognitive behavioral therapy (CBT) representing the most empirically supported approach. Systematic reviews indicate CBT reduces somatic symptom severity and disability through small-to-moderate effect sizes, primarily by modifying maladaptive illness beliefs and reducing avoidance behaviors rather than altering symptom intensity directly. Short-term psychodynamic psychotherapy (STPP) has demonstrated efficacy comparable or superior to CBT in long-term follow-up studies, while third-wave therapies such as mindfulness-based interventions and Acceptance and Commitment Therapy (ACT) target psychological flexibility and experiential avoidance. Psychoeducation regarding the psychophysiological mechanisms of symptoms serves as a foundational component across all modalities, aiming to reframe the patient's understanding of their condition from organic disease to functional dysregulation.<ref name="thelancet.com">{{Cite web |title=Management of functional somatic syndromes: The Lancet |url=http://www.thelancet.com/journals/lancet/article/PIIS0140673607601597/abstract |archive-url=http://web.archive.org/web/20100922191921/http://www.thelancet.com/journals/lancet/article/PIIS0140673607601597/abstract |archive-date=2010-09-22 |access-date=2026-01-19 |website=www.thelancet.com |language=en}}</ref><ref>{{Cite journal |last1=van Dessel |first1=Nikki |last2=den Boeft |first2=Madelon |last3=van der Wouden |first3=Johannes C. |last4=Kleinstäuber |first4=Maria |last5=Leone |first5=Stephanie S. |last6=Terluin |first6=Berend |last7=Numans |first7=Mattijs E. |last8=van der Horst |first8=Henriëtte E. |last9=van Marwijk |first9=Harm |date=2014-11-01 |title=Non-pharmacological interventions for somatoform disorders and medically unexplained physical symptoms (MUPS) in adults |journal=The Cochrane Database of Systematic Reviews |volume=2014 |issue=11 |article-number=CD011142 |doi=10.1002/14651858.CD011142.pub2 |issn=1469-493X |pmc=10984143 |pmid=25362239}}</ref><ref>{{Cite journal |last1=Henningsen |first1=Peter |last2=Zipfel |first2=Stephan |last3=Herzog |first3=Wolfgang |date=2007-03-17 |title=Management of functional somatic syndromes |journal=Lancet |volume=369 |issue=9565 |pages=946–955 |doi=10.1016/S0140-6736(07)60159-7 |issn=1474-547X |pmid=17368156}}</ref><ref>https://psycnet.apa.org/record/2021-33780-001</ref>

Physical therapies for functional somatic syndromes primarily comprise graded exercise therapy, structured aerobic training, and activity-based rehabilitation programs that aim to reverse deconditioning and reduce symptom-focused inactivity. Graded exercise therapy typically involves individually titrated, stepwise increases in physical activity (e.g., walking, cycling) under supervision, with progression guided by time rather than symptoms to prevent reinforcement of avoidance behavior. Additional components include physiotherapy targeting posture, muscle tension, and pain-modulating movement patterns, as well as occupational therapy interventions that systematically rebuild daily functioning and participation in work and leisure activities. These interventions are predicated on evidence that functional symptoms are maintained by a cycle of inactivity, hypervigilance to bodily sensations, and fear-avoidance, and they therefore emphasize behavioral activation and exposure to normal levels of exertion rather than passive modalities such as rest or purely palliative treatments.<ref name="thelancet.com"/><ref>{{Cite journal |last1=Röhricht |first1=Frank |last2=Green |first2=Carole |last3=Filippidou |first3=Maria |last4=Lowe |first4=Simon |last5=Power |first5=Nicki |last6=Rassool |first6=Sara |last7=Rothman |first7=Katherine |last8=Shah |first8=Meera |last9=Papadopoulos |first9=Nina |date=2024-06-03 |title=Integrated care model for patients with functional somatic symptom disorder - a co-produced stakeholder exploration with recommendations for best practice |journal=BMC Health Services Research |volume=24 |issue=1 |page=698 |doi=10.1186/s12913-024-11130-9 |doi-access=free |issn=1472-6963 |pmc=11145802 |pmid=38831287}}</ref>

Medications such as antidepressants may play a role.<ref>{{Cite web|url=https://my.clevelandclinic.org/health/diseases/17976-somatic-symptom-disorder-in-adults#management-and-treatment|title=Somatic Symptom Disorder: What It Is, Symptoms & Treatment|website=Cleveland Clinic}}</ref><ref>{{Cite web|url=https://www.mayoclinic.org/diseases-conditions/somatic-symptom-disorder/diagnosis-treatment/drc-20377781|title=Somatic symptom disorder - Diagnosis and treatment - Mayo Clinic|website=www.mayoclinic.org}}</ref> More direct medication has little if any positive long-term impact.<ref name="auto1">{{Cite web |date=Dec 15, 2023 |title=Non-specific physical disorders (functional somatic syndromes) |url=https://gesund.bund.de/en/functional-somatic-syndromes |website=gesund.bund.de}}</ref>

According to guidance from the German Federal Ministry of Health "the extent to which functional somatic syndromes affect people's lives partly depends on how the people affected deal with them."<ref name="auto1" />

==History== The term functional somatic syndrome was used in a 1999 paper.<ref>{{Cite journal|title=Functional somatic syndromes|first1=A. J.|last1=Barsky|first2=J. F.|last2=Borus|date=June 1, 1999|journal=Annals of Internal Medicine|volume=130|issue=11|pages=910–921|doi=10.7326/0003-4819-130-11-199906010-00016|pmid=10375340}}</ref>

== References == {{Reflist}}

Category:Rheumatology