Other countries warn of psychiatric effects
The FDA approved the 1-mg form of finasteride for male pattern hair loss in 1997.
In 2012, the label and the patient insert were updated to state that side effects included less desire for sex, erectile dysfunction, and a decrease in the amount of semen produced, but that those adverse events occurred in less than 2% of men and generally went away in most men who stopped taking the drug.
That label change unleashed a flood of more than 1,000 lawsuits against Merck. The company reportedly settled at least half of them for $4.3 million in 2018. The Superior Court of New Jersey closed out the consolidated class action against Merck in May 2021, noting that all of the cases had been settled or dismissed.
The suits generally accused Merck of not giving adequate warning about sexual side effects, according to an investigation by Reuters. That 2019 special report found that Merck had understated the number of men who experienced sexual side effects and the duration of those symptoms. The news organization also reported that from 2009 to 2018, the FDA received 5,000 reports of sexual or mental health side effects – and sometimes both – in men who took finasteride. Some 350 of the men reported suicidal thoughts, and there were 50 reports of suicide.
Public Citizen’s lawsuit alleges that VigiBase, which is managed by the World Health Organization Collaborating Centre for International Drug Monitoring, lists 378 cases of suicidal ideation, 39 cases of suicide attempt, and 88 cases of completed suicide associated with finasteride use. VigiBase collects data from 153 countries on adverse reactions to medications.
In February 2021, more documents from the class action lawsuits were unsealed in response to a Reuters request. According to the news organization, the documents showed that Merck knew of reports of depression, including suicidal thoughts, as early as 2009.
However, according to Reuters, the FDA in 2011 granted Merck’s request to only note depression as a potential side effect, without including the risk of suicidal ideation.
The current FDA label notes a small incidence of sexual dysfunction, including decreased libido (1.8% in trials) and erectile dysfunction (1.3%) and mentions depression as a side effect observed during the postmarketing period.
The Canadian label has the same statistics on sexual side effects but is much stronger on mental adverse effects: “Psychiatric disorders: mood alterations and depression, decreased libido that continued after discontinuation of treatment. Mood alterations including depressed mood and, less frequently, suicidal ideation have been reported in patients treated with finasteride 1 mg. Patients should be monitored for psychiatric symptoms, and if these occur, the patient should be advised to seek medical advice.”
In the United Kingdom, patients prescribed the drug are given a leaflet, which notes that “Mood alterations such as depressed mood, depression and, less frequently, suicidal thoughts have been reported in patients treated with Propecia,” and advises patients to stop taking the drug if they experience any of those symptoms and to discuss it with their physician.
Public Citizen noted in its lawsuit that French and German drug regulators have sent letters to clinicians advising them to inform patients of the risk of suicidal thoughts and anxiety.