Finasteride tablets are widely used to treat male pattern hair loss, and each possible side effect is a reason many men hesitate about starting finasteride. This guide covers what drug labels, regulators and reviews say about the known side effects of finasteride, where the evidence is firm, and where it is still disputed. It does not assess whether finasteride works for promoting hair growth, or its effect on hair count or hair follicles. It is general information, not medical advice. Last updated 22 October 2026.
One note on sourcing: we could not open the current FDA label directly. Label figures below come from secondary copies of the Propecia (1 mg) label dated August 2022, so check the current label or ask a pharmacist for the latest wording.
Common side effects of finasteride
The most common side effects of finasteride are decreased libido, erectile dysfunction and ejaculation disorder, according to the Propecia (1 mg) label for oral finasteride. Each occurred in at least 1% of patients and more often than on placebo. For a related topic, see our topical finasteride page.
In the 12-month trials described in the label:
- Sexual adverse events were reported by 3.8% of men on finasteride and 2.1% of men on placebo.
- 1.4% of men on finasteride stopped treatment because of drug-related adverse experiences, compared with 1.6% on placebo.
One telehealth site says sexual effects affect about 1% of men on 1 mg and about 10% on 5 mg. We could not verify the 5 mg figure against primary data, and the numbers are not directly comparable with the trial results above, so treat it with caution.
Breast tenderness or enlargement, rash and allergic reactions are described as rare. For a related topic, see our dutasteride vs finasteride page.
Mood, depression and suicidal thoughts
The FDA has added mental health information to the finasteride label in two steps. Depression was added to the Adverse Reactions section (postmarketing experience) in 2011. In a June 8, 2022 response to a petition from the Post-Finasteride Syndrome Foundation, the FDA required the manufacturer, Organon, to add suicidal ideation and behavior to the same section.
The FDA did not add a boxed warning or a Warnings and Precautions entry for depression, suicidal ideation or persistent sexual dysfunction. It said it found no reasonable evidence of a causal association for depression and could not conclude there was one for suicidal ideation, though it cited the drug's mechanism of action and reports to its adverse event database in support of the new listing.
The same Adverse Reactions section already lists sexual dysfunction that continued after treatment was stopped, and the FDA said its analysis supports keeping that entry. These details come from the FDA's June 2022 petition response. We did not open the current label itself, so check the exact wording there.
If you have low mood or thoughts of self-harm while you take finasteride, get prompt help from a doctor rather than waiting. In the United States, you can call or text 988, the Suicide and Crisis Lifeline, at any time.
Post-finasteride syndrome and symptoms even after stopping
Post-finasteride syndrome (PFS) is the name given to sexual and other symptoms that some men report continuing after they stop taking the medication. It is one of the most contested side effect topics around finasteride. For another angle, see our finasteride vs minoxidil guide.
What is established:
- In 2012, the FDA revised the label to add libido, ejaculation and orgasm problems that continued after discontinuation. It said a causal link had not been established. Its adverse-event database held 59 reports of sexual dysfunction lasting at least three months after stopping.
- The postmarketing section of the label lists persistent sexual dysfunction after discontinuation and notes the reports come from an uncertain population.
What is uncertain:
- A review of the evidence notes that many studies are surveys of men seeking PFS treatment or recruited from online forums, so selection and recall bias are likely. Randomized trials are scarce.
- A 2003 placebo-controlled trial found that symptoms persisting after stopping were more common in the placebo group than in the finasteride group.
- A 2025 review (Cilio et al., "Post-finasteride syndrome – a true clinical entity?") describes PFS as challenging for diagnosis and management. Another review concluded that studies to date cannot refute or confirm PFS as a distinct condition.
- Some authors compare PFS with post-SSRI sexual dysfunction.
In short, finasteride users report persistent symptoms, regulators have acknowledged them in labelling, and the science has not settled whether finasteride causes them or how often. For related reading, see our hair transplant vs non-surgical page.
Fertility and prostate cancer
The label is described as including reports of male infertility or poor semen quality that improved after stopping. We saw this only in a search summary of the label, so it is unverified.
Some consumer sites say finasteride may carry an increased risk of high-grade prostate cancer and male breast cancer. We did not confirm this against the current FDA label. Another secondary source says that question is still debated. If this matters to you, raise it with your doctor, since finasteride is prescribed for an enlarged prostate as well as hair loss.
How often are side effects reported?
Figures differ depending on the source, the dose and how each side effect was counted. The label says at least 1% for individual sexual effects, with 3.8% versus 2.1% on placebo for sexual adverse events overall in trials. A secondary source gives about 1% on 1 mg and about 10% on 5 mg. These cannot be compared directly.
Reports to the FDA's adverse event database are one source of safety signals, and the FDA cited them in its 2022 decision. Spontaneous reports cannot show that the drug caused the events, and we did not find report counts in a primary FDA document.
What to do if you notice side effects
- Do not ignore low mood, thoughts of self-harm or an allergic reaction. Speak to a doctor promptly if depression or suicidal thoughts develop.
- Talk to a doctor or pharmacist about any side effect, such as sexual changes or breast changes, before deciding to stop or continue using finasteride.
- Report any suspected side effect to the FDA through its MedWatch program.
We do not have source-backed evidence on topical finasteride, on finasteride shedding, on combining finasteride with minoxidil, on long-term effects, or on ways to reduce side effects, so we have not made claims about them here. A prescriber can discuss alternatives for hair loss, including non-surgical options.
Frequently Asked Questions
Which side effects are most often reported on the finasteride label?
On the Propecia 1 mg label, the most common are decreased libido, erectile dysfunction and ejaculation disorder, each occurring in at least 1% of patients and more often than on placebo.
Can finasteride side effects continue after stopping?
The FDA added persistent sexual problems after discontinuation to the label in 2012 while saying a causal link had not been established. Reviews say the evidence cannot yet confirm or refute the syndrome as a distinct condition.
Does finasteride cause depression?
Depression is listed on the label, and according to one review the FDA added it in 2011. Anyone who develops depression or suicidal thoughts should stop and speak to a doctor.
Where can I report finasteride side effects?
In the United States, you can report suspected side effects to the FDA through its MedWatch program, online at fda.gov/medwatch or by phone at 1-800-FDA-1088.