Rebuttals to denialists

There’s a cottage industry of physicians casting doubt on 5-alpha syndrome. Their arguments commit logical errors, misread literature and betray a physician-centric attitude.

This website exposes how harms of finasteride have been obfuscated since the 1990s. For example, Merck omitted and minimized adverse events in clinical trials.1 They did the same when the Swedish drugs regulator demanded information on cases of persistent sexual dysfunction and depression linked to finasteride in the 2000s.2 When new warnings were added to the label and Merck faced litigation over the drug’s harms, physicians took to the literature to defend the drug’s safety.3

The arguments they used have significant or fatal weaknesses including: overlooking social context, misreading literature, omitting inconvenient facts, failing to account for industry influence, disparaging patients, and calling for studies without apparent intention to carry out the studies. Rebuttals to these arguments are provided below.

See also: ‘Safe and well-tolerated’: Arguments used to discredit reports of persistent adverse effects

Quick reference

Doubting physician: “Finasteride is safe based on trials and experience”

Rebuttal: The quality of Merck’s safety reporting is questionable and difficult to assess. Social taboos and embarrassment prevent reporting of sexual concerns in all settings.

“Patients are experiencing a nocebo effect”

No evidence for a post-drug nocebo effect has been found.

“Patients are influenced by news, social media, advocacy & more”

Post-finasteride cases were observed and reported in the 1990s and early 2000s, before risks were publicized.

“Patients have pre-existing conditions”

Cases without pre-existing conditions have been described, including one in Merck’s clinical trial and a postmarketing case disclosed by Merck.

“Patients have depression or another mental illness”

Genital abnormalities and numbness are not symptoms of common psychiatric disorders.

“Patients lack expertise to report adverse events accurately”

Symptoms reported by patients and health care providers are similar, although psychological symptoms are more common in reports from health care providers. Research has shown health care providers discount or overlook certain adverse events.

“Studies on 5-alpha syndrome are of low quality”

Studies deemed “high-quality” have industry bias. Other findings are preliminary because the condition is variable, funding is scarce, and the research community is small.

“There is no causal link between finasteride and an alleged syndrome”

A causal link has not been adequately investigated.

“Controlled trials are needed”

Physicians who call for a trial seem to have no intention of carrying it out.

“The disease is ill-defined”

The condition is not well-defined because it has not been adequately studied. Many diseases have previously been “ill-defined,” for example bacterial infections.

“The disease lacks biological plausibility”

The disease has not been adequately studied. The burden should be on researchers to explore a biological basis rather than expecting the disease to match expectations.

“There is a history of controversy surrounding the disease”

Many diseases have been “controversial,” such as long Covid. The presence of disagreement neither supports nor refutes a disease’s validity. Industry influence on the literature should be accounted for.

“I’ve never seen it in my practice”

The syndrome develops after discontinuing the drug and involves embarrassing symptoms, which may prevent patients from reporting back to the doctor. Physicians may have received genuine reports, but denied a link to finasteride.

Detailed responses

“The drug is safe and well-tolerated per clinical trials and clinician experience”

Rebuttal: In Merck’s Phase III extension trial, there was a case of post-finasteride sexual dysfunction which Merck did not disclose to FDA. The drug maker had received at least 100 reports of this outcome as of 2006. Adverse outcomes in other trials were concealed, for example in the PLESS trial where the finasteride group had double the rate of unrecovered sexual dysfunction compared to controls.

The trial population was unrepresentative of a general population (for example, patients were excluded if they had “[a] history of any illness or condition that might have confounded the results of the study or posed additional risk.”4). Online polls suggest that official rates of side effects may be understated by a factor of 6.

Clinicians may not hear about post-finasteride experiences because it develops after treatment has ended. Patients may not attribute adverse experiences to the drug at all. Even if they do, they may be shy about discussing use of a medication for hair loss, and unwilling to broach sexual dysfunction and psychiatric concerns with a doctor—perhaps especially a dermatologist who does not specialize in these areas. Moreover, the dermatologist may signal that he or she is not open to discussion of side effects.

“Patients are experiencing a nocebo effect” (negative expectations bringing on adverse effects)

Rebuttal: Proponents often cite Mondaini et al who found that patients advised about the possibility of side effects reported them at a higher rate than those not advised.5 This study is not relevant to 5-alpha syndrome because the reports occurred while patients were using the drug. In a literature search, no evidence for a post-drug nocebo effect could be found, regarding finasteride or any other drug. Although the nocebo argument appears frequently in literature about 5-alpha syndrome, citing Mondaini et al, it appears to have no basis in evidence.

Even if there were evidence for a post-drug nocebo effect, it could not be used for some cases. The patient with post-finasteride sexual dysfunction after leaving Merck’s extension trial would not have had access to websites, media coverage or warnings that would alert him to this possibility. A self-report of post-finasteride sexual dysfunction was posted in the year 2000. Merck received 100 reports of unrecovered sexual dysfunction after stopping finasteride in the early 2000s, when public information about risks was scarce.

“Media coverage, internet forums, an advocacy group and litigation have led patients to report adverse events”

Rebuttal: Prior to public awareness, taboos and embarrassment over male sexual dysfunction may have suppressed reports. It is possible that awareness is needed to elicit reports. Moreover, before physicians became aware of this outcome, they might have declined to attribute patient reports to finasteride.

The stimulated reporting argument could not explain the case of post-finasteride sexual dysfunction in Merck’s extension trial, other cases in its trials, nor postmarketing reports Merck received in the early 2000s. The first known online report dates from September 2000. A Propecia Side Effects Yahoo group was founded in 2003.

“Patients have pre-existing psychological and sexual disorders”

Rebuttal: Countering this argument, a board-certified urologist and sexual medicine specialist tweeted: “I have personally seen in my practice otherwise completely healthy young men who come in for ED and the only medication they had taken was Finasteride for hair loss.”

The case in Merck’s Phase III extension trial also casts doubt on this argument, because the company excluded men with “[a] history of any illness or condition that might have confounded the results of the study or posed additional risk.”6

A case Merck disclosed to the Swedish drugs regulator in 2006 challenges the pre-existing conditions argument (emphasis added):

[A] 22 year old male emotionally healthy male with no prior history of sexual dysfunction was placed on therapy with finasteride for the treatment of early male pattern balding. Three to four months later the patient began to experience complete loss of sexual drive, including loss of spontaneous erections… Therapy with finasteride was discontinued. Eight months later, the patient reported he continued to experience the same symptoms with no sign of any spontaneous resolution.”7

“Patients are experiencing depression, anxiety or another mental illness”

Rebuttal: Symptoms of depression, anxiety, panic or suicidality do not rule out the presence of another illness. For example, non-psychiatric conditions such as chronic pain, migraines and stroke have an association with depression, but most physicians do not claim that they can be reduced to depression.

Most physicians making these arguments do not have expertise in psychiatry, and have not sought a psychological assessment of patients reporting 5-alpha syndrome.

“Patients lack expertise in reporting their adverse events”

Rebuttal: There has been increasing recognition of limitations of adverse event reporting by physicians, including underreporting,8,9 underestimation of severity and limited scope. Dr. Ethan Basch wrote:

Current drug-labeling practice for adverse events is based on the implicit assumption that an accurate portrait of patients’ subjective experiences can be provided by clinicians’ documentation alone. Yet a substantial body of evidence contradicts this assumption, showing that clinicians systematically downgrade the severity of patients’ symptoms, that patients’ self-reports frequently capture side effects that clinicians miss, and that clinicians’ failure to note these symptoms results in the occurrence of preventable adverse events.10

In a commentary entitled “Should we trust patient-reported outcomes?” Dr. Marie-Christine Nizzi wrote:

The expertise bias holds that physicians are best equipped to speak to patients’ quality of life because their medical knowledge grants them the relevant kind of expertise, which the patients lack. This one-sided view of what constitutes relevant expertise belongs to an outdated model of medicine. At its best, the healthcare relationship is not a tutelage but a partnership, where the physician’s expertise in biological processes is guided by the patient’s expertise in their own thoughts, feelings, and sensations.11

In an analysis of adverse events of finasteride, patient reports included more sexual adverse events while healthcare providers included more psychiatric adverse events. This reflects the deep divide between physicians and patients: patients have a direct experience of sexual adverse events while physicians are prone to interpret the patient’s report in psychological terms. Arguably, the patient is better suited to reporting this type of adverse event, as the physician does not have access to the patient’s experience.

“Studies are of low quality”

Rebuttal: Merck has reported spending $450 million on the development of Propecia.12 Clinical trials resulted in dozens of publications, creating the impression of a large evidence base supporting the drug’s safety—despite the conflict of interest and questionable safety reporting.

Meanwhile, funding to support research on drug harms is scarce. Some early research on 5-alpha syndrome was funded by the Post-Finasteride Syndrome Foundation, with contributions from patients and their relatives. Recruiting for studies is challenging because the disease is shrouded by social taboos and embarrassment. There is heterogeneity in the patient population—for example, time since stopping the drug and the nature of their dysfunctions.

Qualitative, low-budget studies are not necessarily “low quality,” but different from an industry-funded trial. They should be judged based on the context, not on a rigid hierarchy of evidence where studies costing millions of dollars overrule all other forms of evidence. It is entirely expected that early studies on a disease would be descriptive and exploratory. This is why case reports are published in journals.

One study funded by the PFS Foundation was systematic and controlled, including measures of gene expression, steroid levels and brain activity.13 On some measures, there were no differences between the post-finasteride group and controls. Although the authors suggested results from post-finasteride patients resembled depression, the conclusion is debatable based on methodology (the skin biopsy was taken from the back) and their interpretation of brain imaging results.

Rebuttal: Dermatologists and regulators have not undertaken the research needed to assess a causal link. A prospective trial could take a decentralized approach which relies on mobile devices. Another option is a systematic review of evidence. Khan et al noted six criteria for establishing causation in systematic reviews: strength of association, consistency, temporality, specificity, biological gradient, plausibility, coherence and analogy, and experimental evidence.14

Even without such studies, a wide range of evidence is available to assess causation: cases Merck did not disclose until a judge ordered the release of documents in 2021; obfuscated cases from clinical trials; more than 20 years of adverse event data; animal studies; case reports and series; physician perspectives; and media reports going back to 2010. An assessment should account for the influence of industry and physician interests on the medical literature, especially since permanent harms of a medication are at issue.15

“A randomized controlled trial should be conducted”

Rebuttal: It is common to call for prospective trials in conclusions. Gray and Semla wrote: “We need placebo controlled trials using validated questionnaires and long term follow-up after treatment to examine persistence of symptoms.”16 But the researchers who make these calls do not seem to have any intention to carry out those trials or raise funds to support such studies. Leliefeld et al made a realistic observation that a randomized, prospective trial is “unlikely to happen due to a lack of funding.”17

Given the lack of funding, researchers could suggest other types of studies such as a decentralized trial, perhaps in partnership with telehealth companies or health systems.

“The proposed disease ‘post-finasteride syndrome’ is ill-defined”

Rebuttal: Any problem worth studying is not well-defined (for example, cosmology or long Covid). Once problems are well-defined, they can be put in an encyclopedia and investigators can move on to other problems which are not well-defined.

Post-finasteride syndrome has not been adequately studied. The onus should be on researchers to study it, rather than for the disease to define itself. This is a hard problem. The speaker implies she dislikes that it’s hard, and questions its validity rather than investigating.

“No mechanism for permanent adverse effects can be conceived. The disease lacks biological plausibility”

Rebuttal: The disease has not been adequately studied. The burden should be on researchers to explore a biological basis rather than expecting the disease to meet their prior expectations.

Meanwhile, it turns out that the most common symptoms and dysfunctions of 5-alpha syndrome rely on organs and tissues dependent on steroid signaling, for example the reproductive system, hypothalamus and eyes. Finasteride interferes with these pathways. There is evidence of penile damage in men with the syndrome, while dihydrotestosterone (DHT), the androgen suppressed by finasteride, is critical for early development of the male genitals. It is entirely plausible that DHT may be involved in maintenance of penile tissue in adult men. Moreover, low DHT is associated with inflammation.

It is easier to express doubt than to acknowledge a lack of understanding, and then investigate.

“The syndrome has been controversial”

Rebuttal: The mere presence of controversy does not support or rule out any position. The origins of Covid, climate change and the germ theory of disease have all been controversial. This means there was disagreement. This argument amounts to a defense of the status quo, and perhaps also interests which benefit from it.

“I’ve never seen it in my practice”

Rebuttal: The physician assumes her knowledge and experience are authoritative, while overlooking factors that might prevent reporting 5-alpha syndrome back to the physician. It develops after discontinuation of the drug. It involves embarrassing symptoms that violate social taboos. The affected individual may not attribute his problems to the drug. He may feel it is inappropriate to report sexual or psychiatric problems to a dermatologist. Or, the physician may hear a genuine report but deny a link to finasteride. In this case, she has seen it in her practice, but denied its validity. Finally, physicians may resist acknowledging treatment-related harms because of concerns about liability.

  1. See The lost men, and Since 1994, Merck has been aware of unresolved sexual dysfunction… ↩︎
  2. Merck’s response to the Swedish drugs regulator. ↩︎
  3. See: Responding to a literature of doubt, ‘Safe and well-tolerated’, Response to Dr. Ralph Trüeb and Temperature check. ↩︎
  4. Merck Research Laboratories. Drug Approval Package: Propecia NDA #020788; Trial 087. Drugs@FDA. December 19, 1997. ↩︎
  5. Mondaini N, Gontero P, Giubilei G, et al. Finasteride 5 mg and sexual side effects: how many of these are related to a nocebo phenomenon? J Sex Med. 2007. doi:10.1111/j.1743-6109.2007.00563.x ↩︎
  6. Merck Research Laboratories. Drug Approval Package: Propecia NDA #020788; Trial 087. Drugs@FDA. December 19, 1997. ↩︎
  7. Merck Research Laboratories Worldwide Product Safety. Periodic Safety Report for: Finasteride, 1 mg tablet and 0.2 mg tablet, MSD. November 30, 2006. View at ↩︎
  8. Hazell L, Shakir SA. Under-reporting of adverse drug reactions: a systematic review. Drug Saf. 2006. doi:10.2165/00002018-200629050-00003 ↩︎
  9. Lopez-Gonzalez E, Herdeiro MT, Figueiras A. Determinants of under-reporting of adverse drug reactions: a systematic review. Drug Saf. 2009. doi:10.2165/00002018-200932010-00002 ↩︎
  10. Basch E. The missing voice of patients in drug-safety reporting. N Engl J Med. 2010. doi:10.1056/NEJMp0911494 ↩︎
  11. Nizzi MC. Should we trust patient-reported outcomes? AJOB Neurosci. 2021 Apr-Sep. doi:10.1080/21507740.2021.1904040 ↩︎
  12. Morrow DJ. New Baldness Drug Is Older Product at a Premium PriceNew York Times. January 20, 1998. ↩︎
  13. Basaria S, Jasuja R, Huang G, et al. Characteristics of men who report persistent sexual symptoms after finasteride use for hair loss. J Clin Endocrinol Metab. 2016. doi:10.1210/jc.2016-2726 ↩︎
  14. Khan KS, Ball E, Fox CE, et al
    Systematic reviews to evaluate causation: an overview of methods and application
    BMJ Evidence-Based Medicine 2012. doi:10.1136/ebmed-2011-100287 ↩︎
  15. Abramson J. Sickening: How Big Pharma Broke American Health Care and How We Can Repair It. Mariner Books; 2022. Amazon ↩︎
  16. Gray SL, Semla TP. Post-finasteride syndrome. BMJ. 2019. doi:10.1136/bmj.l5047 ↩︎
  17. Leliefeld HHJ, Debruyne FMJ & Reisman Y. The post-finasteride syndrome: possible etiological mechanisms and symptoms. Int J Impot Res. 2023. doi:10.1038/s41443-023-00759-5 ↩︎