How Merck buried finasteride’s full impact on hormone signaling
Merck held that finasteride had a simple and selective mechanism. In fact, it disrupts hormonal pathways much more broadly. These pathways support the brain, reproductive system and other organs. Merck’s selective account concealed risks which would surface in the decades after approval of Propecia.
Research review: Alterations to penile and prostatic tissue associated with finasteride and dutasteride treatment
Simple summary: Numerous studies have shown that treatment with finasteride and dutasteride can change the size, tissue composition and function of the penis and prostate. Changes in the penis linked to finasteride or dutasteride treatment include: reduced size and weight; reduced erectile response; decreased smooth muscle; increased collagen density; fibrosis (scarring); smaller cavities for blood … Read more
The lost men: how Merck, GSK papered over bad outcomes in trials
A re-examination of clinical trials of finasteride and dutasteride reveals warning signs of long-term harms to surface later.
The lost men – appendix
A summary of men who had unresolved and severe adverse events in clinical trials of finasteride and dutasteride.
From LSD to Zoloft, drugs can leave lasting damage
SUMMARY: Post-drug disorders are not side effects that linger, but lasting changes that may be severe and irreversible. These disorders are linked to prescribed drugs as well as recreational drugs, and can arise after one dose or chronic abuse. This post covers post-drug disorders linked to use of alcohol, hallucinogens, antidepressants, benzodiazepenes, isotretinoin (also known … Read more
Firsthand reports – Volume XIII: User reviews
The websites Drugs.com and Ask a Patient collect reviews of drugs. Here are selected reviews of finasteride, taken by men for hair loss conditions. The dates range from 2008 to 2023.
Firsthand experiences – Volume XI: Videos
Click the video title to view on YouTube where you’ll find a description and comments.
Andrew Huberman, PhD discusses post-finasteride syndrome on the Huberman Lab podcast
Today’s episode of the popular Huberman Lab Podcast is titled “The Science of Healthy Hair, Hair Loss and How to Regrow Hair.” It includes a five-minute discussion of post-finasteride syndrome. In the segment, Huberman raises an issue that has been little-discussed in the literature: the role of the androgen dihydrotestosterone (DHT) in development throughout the … Read more
Regulators are waking from their slumber
Agencies in France, the United Kingdom, Canada and the United States are strengthening warnings about finasteride risks
A rundown of new bibliographies & research guides
The research base spans many disciplines and goes back almost 50 years. To help researchers get oriented, an on-ramp was added. In the Systems & functions area, a new bibliography was added: Adverse effects on skin, comprising nine case reports. The gynecomastia bibliography has been expanded. The bibliography on the musculoskeletal system has been expanded … Read more
2022 – year in review
Regulators added warnings, the New York Post covered finasteride harms, and two influencers urged followers to avoid the drug.
In June 2022, the FDA required the addition of ‘suicidal ideation and behavior’ to the Propecia (finasteride 1 mg) label. In July, France’s national drug regulator ANSM added materials to help patients better understand the risks of finasteride.
Hair or manhood—choose one?
In ancient Greece, Hippocrates and Aristotle observed that eunuchs did not go bald. Jumping ahead to the early 1940s, American anatomist James B. Hamilton reviewed histories of men with testosterone deficiency and found a pattern: the earlier the age of hormone deficiency, the less balding occurred.
Musculoskeletal adverse events of finasteride
When men take finasteride for hair loss, their attention is directed to the hair and scalp. When adverse events (AEs) occur in other systems and areas of the body, it might not be obvious that finasteride could be the culprit. But the drug serves to lower dihydrotestosterone in the blood as well as peripheral tissue … Read more
Disability and deaths in men who used finasteride
Databases of drug adverse events contain tremendous variation. They include reports from patients of all ages, and many took other drugs that might explain outcomes. In this analysis, cases were limited to men ages 18–40 where the ‘Suspected Product’ field only contained finasteride (or, in the comparison below, minoxidil). This is only a fraction of … Read more
FDA quashed internal warning on suicidality linked to Propecia; changed course in 2022
In 2010, Merck requested to add a warning of depression to the Propecia label. A safety group within FDA concurred, but FDA’s dermatology products group did not support the change. Over a decade later, FDA required the addition of ‘suicidal ideation and behavior’ to the Propecia label.
This site describes adverse experiences which some may find disturbing. See the Reader advisory.
Places to start
- Thinking about taking finasteride for hair loss? See Weighing the risks.
- This post compiles research on changes in penile tissue and function associated with finasteride and dutasteride treatment.
- For a historical perspective, see the timeline which starts with a study in Dominican Republic in the early 1970s.
- The research bibliography gathers hundreds of papers on adverse effects of finasteride and other 5-alpha reductase inhibitors. See also Research by system & function.
5-AR deficiency Adverse effects Adverse event reports Animal studies Antidepressants Anxiety Bias Bibliography Clinical trials Conflict of interest Denial and skepticism Dermatologists Dermatology Doctor views Documents Drug label Dutasteride Europe FDA Firsthand reports Fluoroquinolones FOIA requests Hair transplant surgeons History Merck Merck files News Penile abnormalities Persistent adverse effects Pharmacology Pharmacovigilance Polls Post-finasteride syndrome Propecia Psychological adverse effects Recoveries Research Sexual adverse effects Sexual dysfunction Shame and stigma Social attitudes Social context Social media SSRIs Video