• ‘We know that this is a safe drug’: NBC story hints finasteride syndrome is due to prior health problems

    A recent NBC News story accentuated the positives about finasteride for hair loss. It’s “extremely effective,” said Dr. Jerry Shapiro. “It’s like water in my clinic. I’m prescribing it all the time.” Closing out the article, he said the risk of permanent problems is “so, so rare. I’ve never seen it in a patient, and…

  • Firsthand experiences XVIII: ‘Wish I could go back in time and not take it’

    Earlier this month the YouTube channel Cortex Labs posted a long video titled “Post Finasteride Syndrome Deniers – A Dangerous Precedent.” It drew hundreds of comments, some of which described ongoing problems after stopping finasteride. Below is a selection of these comments, posted between June 11 and today. rcbash*** 3.5 years of this nightmare. Thank…

  • Firsthand experiences XVII: ‘The mental stuff was like, wow’

    In this brief video, a user says the hardest part of his post-finasteride experience was mental difficulties. He does not go into detail except to say he had suicidal thoughts and “mental fog.” In college at the time, he began working out and stopped drinking alcohol for a period. Later on, when he had a…

  • Firsthand experiences XVI: ‘My memory had dropped profoundly… my speech was slurred’

    A user wrote on a Reddit hair loss forum: “A month after I started noticing that my brain functionality had dropped, words were missing or incomplete and my memory had dropped profoundly. I couldn’t recall what I had for lunch an hour after eating. I was stumbling over words, my speech was slurred. I was…

  • Recent studies of adverse events

    A wave of studies of adverse event reports link finasteride to sexual disorders as well as cognitive dysfunction. The field of pharmacovigilance assess the effects of drugs as they are used in the real world. Researchers often use adverse event (AE) data from FDA’s FAERS database or the World Health Organization’s EudraVigilance database. The records,…

  • Merck’s former physician-allies sowed doubt while Propecia litigation was pending

    In a burst of output in the late 2010s, key opinion leaders stressed that a causal role for the drug couldn’t be proved—a welcome message for Merck’s litigation defense After FDA approved finasteride for male hair loss in 1997, the drug’s reputation stayed unblemished for a dozen years in the United States. However, the tide…

  • Firsthand experiences XV: Male infertility

    M30 and F30 had been trying to conceive baby, from over a year. Four months ago, i went for sperm test and got to know that my sperm quality had drastically declined. And i have asthenospermia. The motile sperm were only 20% which should be at least 40.

  • 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…

  • Medical journals and physicians ignore conflicts of interest after a few years

    Physician-researchers known as key opinion leaders have a crucial role in launching a drug into the marketplace. While Propecia litigation was underway in the 2010s, a number of opinion leaders who had helped Merck launch Proscar and Propecia wrote articles defending the drug’s safety.

  • ChatGPT: Millions of American men take finasteride for hair loss

    The AI service derives an estimate using the percentage of balding men who may take the drug. The estimated range is 2.5 million to 5 million men. Telehealth companies such as Hims and Keeps may be influencing the real figure, but this is not mentioned.

  • Firsthand experiences XIV: Recent reviews on Drugs.com & Ask a Patient

    More reviews have been posted online since a compilation was published in 2023. While some are positive, others are alarming and consistent with adverse event reports submitted to FDA as well as media reports and some research. Find recent negative reviews from the Drugs.com and Ask a Patient websites below. Emphasis has been added in…

  • New bibliography of case reports and series

    A new bibliography of case reports & series is available. The papers come from a wide range of medical specialties including dermatology, hematology, hepatology, neurology, ophthalmology, pediatrics and andrology. Most were already in the main bibliography, but a few new ones were discovered. View the new bibliography: Case reports & series

  • Research responses

    Below are responses by the Finasteride Watch editor to peer-reviewed research on harms of finasteride and dutasteride.

  • Reckoning with underreporting—response to Lauck et al, 2024

    We do not know if the medical records used in this study are sensitive to sexual dysfunction in healthy men, and especially in men taking these drugs for hair loss. Since the study includes men taking 5-ARIs, the results do not shed light on why sexual dysfunction might persist after stopping these drugs.

  • Against armchair medicine: a retort to skeptical physicians

    Physicians have used flimsy arguments to cast doubt on 5-alpha syndrome. They overlook social context, misread literature, omit inconvenient facts and disparage patients. Rebuttals for each of these arguments are provided.

  • Study of depression from prostate drugs loses the signal by including past users

    This study fails to assess the risk of depression associated with using finasteride or dutasteride because past users of 5-ARIs were counted as cases. 37% of cases in the 5-ARI group had stopped taking the drug 181 days or more prior to initial diagnosis or treatment for depression. Only slightly more than half of cases…

  • Study of ED risk loses the signal by including past users of finasteride

    There is a major limitation: the analysis included past and recent users of 5ARIs, as well as current users. Past users are defined as those who stopped taking a 5ARI at least 91 days before getting diagnosed or treated for ED. Recent users are those who last took the drug 31-90 days before diagnosis or…

  • Mind the gaps: remarks on the evidence base

    This post makes a few not-so-obvious points about the sprawling literature on finasteride and 5-alpha syndrome. If you are new to this literature, consider starting with a brief history of the research and a guide for researchers. Those pages describe what is in the literature, but it is also important to discern what is not…

  • 2023 – year in review

    Fitness influencers and physicians raised alarms about risks of finasteride for hair loss this year, reaching millions of people through tweets, videos and podcasts. On the regulatory front, in France boxed warnings were added to finasteride packaging. Health Canada added a warning about suicidality while the UK regulator launched a safety review. Forty-four relevant research…

  • Most popular pages in 2023

    This year traffic jumped more than 70% over 2022. Here’s a rundown of the 10 most popular pages in 2023.

  • Finasteride appears on Prescrire’s latest ‘Drugs to Avoid’ list

    Prescrire, an independent patient safety organization based in France, has updated its Drugs to Avoid guide. Finasteride appears in the 2024 edition, and has also been included in past editions. The guide notes: Finasteride 1 mg, a 5-alpha reductase inhibitor, has very modest efficacy in androgenic alopecia in men: it increases hair density on the…

  • Stanford urologist discusses risks of finasteride on Huberman Lab podcast

    On November 6, Dr. Andrew Huberman spoke to guest Dr. Michael Eisenberg, a urologist and professor at Stanford Health Care in California. In one segment, they discussed post-finasteride syndrome.

  • Temperature check on recent literature

    5-alpha syndrome (post-finasteride syndrome) is appearing more regularly in the medical literature. Recent articles show slightly more openness to the syndrome as legitimate, especially in the fields of andrology and sexual medicine. But they continue to recycle old arguments that pin the problem on the patient, such as pre-existing psychological and sexual disorders, a nocebo…

  • Response to Campbell et al on finasteride-associated suicide and depression in men treated for hypogonadism and impotence

    The clear and concerning results in this abstract are statistically significant RORs for suicidal and self-injurious behaviors, anxiety disorders and depressed mood disorders in the finasteride-only group. The suggestion that combination therapy could “decrease” risk or have a “protective” role is unwarranted because the risk ratios are derived from unrelated sets of cases. This study…

  • Urology professor Dr. Ted Schaeffer on Attia Drive: Post-finasteride syndrome is real, drug-related and can be permanent

    Dr. Schaeffer, Chair of Urology at Feinberg School of Medicine, does not recommend finasteride for any man. The prostate cancer expert says he knows people who have post-finasteride syndrome “permanently.” Dr. Edward Schaeffer recently spoke about post-finasteride syndrome on The Peter Attia Drive Podcast, in an episode on prostate health. Dr. Schaeffer is Chair of…

  • Response to Dr. Ralph Trüeb’s writings on post-finasteride syndrome

    A drug-induced syndrome is all in the mind, a Swiss doctor wrote. Editors of the journals had past ties to the drug maker.

  • Appendix: response to Trüeb

    This appendix accompanies the article: Response to Dr. Ralph Trüeb’s writings on post-finasteride syndrome. Table of competing interests ← back to main article Engagements with Merck re: Propecia Skin Appendage Disorders (journal) (1) International Journal of Trichology (2) Experimental Dermatology (journal) Hair Growth and Disorders textbook (2008) Cited by Trüeb Ralph Trüeb, MD Member, Editorial…

  • Seeking a medical sign of genital numbness

    Some post-5ARI patients experience genital numbness. This symptom can be assessed, but the tests are not easily accessible. This post gives an overview of medical tests which could yield signs of genital numbness and other abnormalities.

  • 2023 – mid-year update

    Drug regulators in France and Canada announced new warnings. A popular podcast discussed post-finasteride syndrome, while men’s fitness influencers urged followers to avoid finasteride.

  • 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.

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.


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Harvesters by Pieter Breughel the Elder, 1565 (via Met Museum Open Access)