Finasteride side effects: what the evidence actually says
Updated
Finasteride is the most proven pill for male pattern hair loss, and also the one with the most worry around it online. Both the benefits and the risks are real. Here is what the evidence says, without the scare stories or the sales pitch.
This is general education. A doctor who knows your health history should make the call with you.
Sexual side effects
In the large 1998 trials of finasteride 1 mg, about 3.8% of men taking it reported a sexual side effect (lower libido, erectile issues, or less ejaculate), compared with about 2.1% of men taking a placebo. So most men notice nothing, and a small number do.
In those trials, the side effects went away in men who stopped the drug, and in many who kept taking it.
Mood changes
Depression and, more rarely, suicidal thoughts have been reported, and the FDA label for finasteride includes a warning about them. If your mood drops after starting, stop and talk to your doctor. If you have a history of depression, raise it before you start.
Symptoms that last after stopping
Some men report sexual, mental, or physical symptoms that continue after stopping, often called post-finasteride syndrome. How often this happens and what causes it are still debated, and good data is limited. It is worth knowing about, and it is one reason to start only after a real conversation with a doctor.
Other things to know
- It lowers PSA, a blood test used to screen for prostate cancer, by about half. Tell any doctor ordering a PSA test that you take it.
- Pregnancy: women who are or may be pregnant should not handle crushed or broken tablets.
- Benefits stop if you stop. The hair it protected is gradually lost over the following year.
If you are worried about side effects
- Topical finasteride targets the scalp with lower levels in the blood, though some still gets through.
- Topical minoxidil works differently, with no effect on hormones.
- Low-dose oral minoxidil is another prescription option with its own, different side effects.
Whatever you choose, the cheapest legitimate way to get finasteride is a generic prescription filled at a discount pharmacy, typically $5–$10 a month. See what hair loss treatment really costs.
Common questions
How common are finasteride side effects?
In the main trials, sexual side effects were reported by about 3.8% of men on finasteride versus about 2.1% on placebo. Most men have no side effects.
Do finasteride side effects go away?
For most men who get them, yes, after stopping and sometimes while continuing. Some men report lasting symptoms after stopping, which is still being studied.
Is topical finasteride safer?
It is designed to keep blood levels lower, and early trials found fewer body-wide effects. Long-term data is limited, and side effects are still possible.
Sources
- Kaufman et al., 1998, J Am Acad Dermatol: Finasteride in the treatment of men with androgenetic alopecia
- FDA Propecia (finasteride) prescribing information
- Piraccini et al., 2022, J Eur Acad Dermatol Venereol (topical finasteride)
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