Quick answer: Most men who take finasteride 1 mg for hair loss have no side effects, but a minority report lower libido, erectile changes or ejaculation changes. A meta-analysis of 15 placebo-controlled trials found finasteride raised the risk of sexual dysfunction by about 1.66 times. Mood changes have also been reported, and in 2019 Health Canada concluded there may be a link between finasteride and suicidal thoughts, asking for a label warning. Effects usually stop when the drug is stopped, though a small number of men report symptoms that persist.
How finasteride works
Finasteride blocks type 2 5α-reductase, the enzyme that converts testosterone into DHT. At 1 mg a day it cut scalp DHT by 64% in a biopsy study of 249 men (Drake 1999). That's why it works for hair loss. DHT also plays roles elsewhere in the body, including sexual function, which is where most of the side effects come from.
Sexual side effects: how common are they?
A 2019 meta-analysis pooled 15 randomized, double-blind, placebo-controlled trials with 4,495 men taking finasteride 1 mg or dutasteride 0.5 mg for hair loss. Finasteride carried a relative risk of 1.66 for sexual dysfunction compared with placebo (Lee 2019). In plain terms: the absolute risk is low, but it is real and higher than placebo.
There's a caveat. A 2015 review in JAMA Dermatology examined 34 finasteride hair-loss trials and found that none had adequate safety reporting, most tracked safety for a year or less, and the data appeared biased toward under-detecting sexual side effects (Belknap 2015). The true rate may be higher than the original trials suggested.
Mood and mental health
In February 2019, Health Canada completed a safety review and concluded there may be a link between finasteride (Propecia and Proscar) and the risk of suicidal ideation. It could neither confirm nor rule out cause and effect, and asked the manufacturer to add a warning to the Canadian product information (Health Canada summary safety review).
A 2021 systematic review found depressive symptoms in 3.33% of men taking finasteride versus 2.54% of men not taking it (Pompili 2021).
If you take finasteride and notice changes in your mood, talk to your doctor promptly. If you are in crisis, call or text 9-8-8, Canada's Suicide Crisis Helpline.
Do finasteride side effects go away?
For most men who have them, yes: side effects typically resolve after stopping the drug. A smaller group reports symptoms that persist after stopping, sometimes called post-finasteride syndrome. In one study of 71 men with persistent symptoms, the effects had lasted an average of 40 months after their last dose (Irwig 2011). That study recruited men who already had persistent symptoms, so it shows these cases exist but not how often they happen.
Summary: finasteride's trade-offs
| Question | What the evidence says |
|---|---|
| Does it work for hair loss? | Yes. It's one of the most effective treatments available. |
| Sexual side effects? | About 1.66 times the placebo risk across 15 trials; trial reporting likely under-counts them |
| Mood side effects? | Reported; Health Canada flagged a possible link to suicidal thoughts in 2019 |
| Do they resolve? | Usually, after stopping; a minority report persistent symptoms |
| Prescription needed in Canada? | Yes |
Should you stop taking finasteride?
Not on your own. If finasteride is working and you feel fine, there's no reason to stop. If you have side effects, raise them with your doctor, who can discuss dose, timing or alternatives. When finasteride stops, scalp DHT climbs back and hair gained on it can gradually be lost, so plan any change.
Alternatives if finasteride isn't for you
The natural options closest to finasteride act on the same enzyme. Saw palmetto improved hair density in 83.3% of patients across seven studies, and pumpkin seed oil raised hair count 40% versus 10% on placebo in a 24-week trial. Both were well tolerated. They are milder than finasteride, so they suit early hair loss best. Compare every option in finasteride alternatives.
DHT Defense Hair Oil combines saw palmetto and pumpkin seed oil with rosemary and bhringraj in a light scalp oil. Made in Toronto, no prescription.
Frequently asked questions
What percentage of men get side effects from finasteride?
Most don't. Across 15 placebo-controlled trials, finasteride raised the risk of sexual dysfunction by about 1.66 times compared with placebo. Because trial safety reporting was weak, the true rate may be somewhat higher.
Are finasteride side effects permanent?
Usually not; they typically resolve after stopping. A minority of men report symptoms that persist, and researchers are still studying how often this happens.
Did Health Canada issue a warning about finasteride?
Yes. In 2019 Health Canada concluded there may be a link between finasteride and suicidal ideation and asked for a warning in the Canadian product information.
Is topical finasteride safer?
Topical finasteride produces lower blood levels than the pill, but it is still finasteride. Ask your doctor whether it suits you.
Is there a natural alternative to finasteride?
Saw palmetto and pumpkin seed oil target the same enzyme and were well tolerated in trials. They are gentler and less potent than finasteride.
Related reading
- Finasteride alternatives: natural and prescription options compared
- Natural DHT blockers for hair loss: what the research shows
- DHT, Explained: the full guide
References
- Drake L, et al. The effects of finasteride on scalp skin and serum androgen levels in men with androgenetic alopecia. J Am Acad Dermatol. 1999. PMID 10495374
- Lee S, et al. Adverse sexual effects of treatment with finasteride or dutasteride for male androgenetic alopecia: a systematic review and meta-analysis. Acta Derm Venereol. 2019. PMID 30206635
- Belknap SM, et al. Adverse event reporting in clinical trials of finasteride for androgenic alopecia: a meta-analysis. JAMA Dermatol. 2015. PMID 25830296
- Health Canada. Summary Safety Review: Proscar and Propecia (finasteride), assessing the potential risk of suicidal ideation. 2019. Link
- Pompili M, et al. Risk of depression associated with finasteride treatment. J Clin Psychopharmacol. 2021. PMID 33814544
- Irwig MS, Kolukula S. Persistent sexual side effects of finasteride for male pattern hair loss. J Sex Med. 2011. PMID 21418145