The most far-fetched theories of post-finasteride syndrome

The two most far-fetched theories of post-finasteride syndrome were proposed by a dermatologist and a hair transplant surgeon. Physicians in these specialties tend to fervently deny that the syndrome is a valid medical condition, pointing instead to co-occurring conditions such as diabetes, anxiety, depression or, according to the theories below, delusions or sleep apnea.

Theory 1: Delusional disorder

In 2019 the Swiss dermatologist Dr. Ralph Trüeb and colleagues proposed an elaborate theory1 (discussed at length in a separate post). They suggested that post-finasteride syndrome is an “induced delusional disorder” arising in men with histrionic personality disorder, who experience a nocebo effect when they read online forums about the condition. The theory is based on Dr. Trüeb’s impressions of a single case. No new systematic evidence is provided. The link between male pattern hair loss and histrionic personality disorder relies on a misreading of a 1994 paper (see box in this post). Finally, Dr. Trüeb and co-authors appear to lack credentials in psychiatry or psychology, and did not appear to order psychological evaluations of patients, so the theory was not tested.

The theory is based on Dr. Trüeb’s impressions of a single case. No new systematic evidence is provided.

As background, the Editor-in-Chief of the journal which published this paper, Dr. Antonella Tosti, has disclosed roles as a consultant and speaker for Merck, and co-authored papers on finasteride with Merck researchers.

Theory 2: Sleep apnea as a contributing factor

The second theory was published by hair transplant surgeon Dr. Aditya K. Gupta of the University of Toronto and two colleagues.2 It rests on a finding of elevated risk of obstructive sleep apnea (OSA) linked to finasteride. The authors reason as follows: Because there is a complex relationship among androgen levels, “sleep architecture” and OSA, and post-finasteride syndrome (PFS) may include sleep disturbances, OSA may contribute to PFS symptoms such as erectile dysfunction, fatigue and depression. They also link finasteride to type 2 diabetes which is in turn associated with OSA. OSA is “treatable,” they write, and “patients complaining of PFS-related symptoms may benefit from a further sleep evaluation to rule out underlying OSA.” In other words, what patients think is post-finasteride syndrome may be, at least in part, OSA, a treatable condition.

On-drug effects cannot be assumed to apply to post-finasteride syndrome.

This line of reasoning has a fatal flaw: the OSA finding is based on FDA data which typically describes on-drug adverse effects. PFS is a post-drug condition. On-drug effects cannot be assumed to apply to PFS. The authors’ findings therefore do not show a link between OSA and PFS. As a result, their deductions about OSA as a mediating factor in PFS are invalid.

As background, Dr. Aditya K. Gupta has been a member of the International Society for Hair Restoration Surgery. Hair restoration surgeons are frequent prescribers of finasteride. Dr. Gupta has disclosed a role as an investigator for Merck and numerous other ties to pharmaceutical companies.3


  1. Trüeb RM, Régnier A, Dutra Rezende H, Gavazzoni Dias MFR. Post-finasteride syndrome: an induced delusional disorder with the potential of a mass psychogenic illness? Skin Appendage Disord. 2019. doi:10.1159/000497362 • PubMed ↩︎
  2. Gupta MA, Vujcic B, Gupta AK 💊 [details]. Finasteride use is associated with higher odds of obstructive sleep apnea: results from the US Food and Drug Administration Adverse Events Reporting System. Skinmed. 2020 May 1;18(3):146-150. Via journal site • PubMed ↩︎
  3. Gupta AK, Gupta G, Jain HC, et al. The prevalence of unsuspected onychomycosis and its causative organisms in a multicentre Canadian sample of 30 000 patients visiting physicians’ offices. J Eur Acad Dermatol Venereol. 2016. doi:10.1111/jdv.13677PubMed ↩︎