Quick answer
In a 24-week phase III trial of 458 men, one topical finasteride spray raised the average hair count in the measured target area by 20.2 hairs, against 21.1 for oral finasteride 1 mg and 6.7 for placebo. Peak blood levels were about 200 times lower, and blood DHT fell less. Lower exposure is not zero exposure. The trial was short, tested one product and included only men.
Finasteride is a prescription medicine used for male pattern hair loss. Many men worry about its side effects, and that is why they ask whether a topical version carries less risk. One trial measured how much drug reaches the blood. It did not settle the question of side effects, so it helps to see exactly what was measured.
What finasteride does
Pattern hair loss in men is driven in part by dihydrotestosterone (DHT), a hormone made from testosterone by the enzyme 5-alpha reductase. Finasteride blocks that enzyme, which lowers DHT and slows the shrinking of hair follicles. It is a prescription treatment, and whether it suits you is a decision for a doctor.
What the phase III trial found
In a randomised, double-blind trial, 458 men with androgenetic alopecia used a topical finasteride 0.25% spray, oral finasteride 1 mg, or a placebo for 24 weeks at 45 sites in Europe (Piraccini et al., JEADV).
| Arm (24 weeks) | Change in target-area hair count (hairs) | Peak plasma finasteride, week 12 | Serum DHT, week 24 |
|---|---|---|---|
| Topical 0.25% spray | 20.2 | 36.5 pg/mL | 34.6% lower |
| Oral 1 mg | 21.1 | 7,166 pg/mL | 55.6% lower |
| Placebo | 6.7 | not applicable | unchanged |
The spray was significantly better than placebo for hair count and numerically close to the oral treatment. A 34.6% fall in blood DHT with the spray is a measurable effect on the whole body, even though it is smaller than with the tablet. On side effects, the overall incidence of adverse events did not differ meaningfully between the spray and placebo, and no serious events were judged treatment-related.
The authors write that these findings make systemic side effects related to lower DHT less likely with the spray than with the tablet, but that they do not exclude such events in either group.
What this trial cannot tell you
A trial of 458 men split across three groups for 24 weeks cannot show how often uncommon or late-appearing effects occur, such as sexual or mood changes. "No meaningful difference from placebo" is not the same as "no risk". The trial also measured drug and DHT levels in blood, which are indirect signs, not side effects themselves. It included only men, and it tested one specific spray.
What regulators say about oral finasteride
Sexual side effects such as reduced desire and erectile problems are listed for finasteride. A meta-analysis reviewed by the UK regulator found a relative risk of 1.6 (95% confidence interval 1.2 to 2.3) for adverse sexual effects against placebo in men taking finasteride 1 mg for hair loss, although many included studies relied on self-reported events (MHRA safety review). A relative risk of 1.6 means the estimated chance was about 1.6 times that of placebo, and the true figure could plausibly lie anywhere from 1.2 to 2.3 times. It does not mean that most men are affected.
In 2025 the European Medicines Agency confirmed suicidal thoughts as a side effect of finasteride tablets, with a frequency that cannot be estimated from the data. It advises anyone who notices mood changes to seek medical advice, and to stop finasteride 1 mg if they are taking it (EMA).
Why "topical" does not mean "risk-free"
The trial tested one specific spray. Its results do not automatically apply to every topical or compounded product, whose strength, vehicle and dose can differ.
The US Food and Drug Administration has warned that absorption of topical finasteride through the skin is expected. It received 32 reports between 2019 and 2024 of adverse events consistent with oral finasteride after compounded topical products. These are spontaneous reports, so they cannot show how often problems occur. The FDA also noted that some patients said they were told there was no risk because the product was topical. It points to local reactions such as irritation, and to the possibility of the product passing to other people through contact, especially women (FDA alert on compounded topical finasteride).
In short, the evidence supports "lower exposure than the tablet in one trial", not "no side effects".
Who needs particular care
Finasteride is contraindicated in pregnancy, and the FDA warns that topical products can pass to other people through contact, especially women (FDA alert). If you live with a woman, especially one who is pregnant, tell your doctor before any finasteride product is prescribed or used at home, and keep the product away from her skin. Tell your doctor about any history of low mood, anxiety or sexual problems too.
If you notice a symptom
If you use finasteride in any form and notice low mood, anxiety, loss of interest in sex, erection problems or any other change that worries you, take it seriously. You are not overreacting by asking. Contact the doctor who prescribed it, or any doctor, soon, and do not wait for it to pass. For mood changes, the European Medicines Agency's advice, written about finasteride tablets, is to seek medical advice and to stop finasteride 1 mg if you are taking it. If you use a spray or another form, contact your prescriber the same day and ask whether to stop. A doctor can work out whether the medicine is the cause or something else is, and can change or stop the plan. Redness, burning or itching where a spray is applied is also worth reporting.
If you ever have thoughts of harming yourself, get help the same day. Tell someone you trust and go to the nearest emergency department.
The bottom line
One topical finasteride spray raised hair counts and gave far lower blood levels than the tablet in one 24-week trial in men. That does not show the same for other topical or compounded products, it does not show long-term safety, and it does not remove the need for a doctor, informed consent about side effects, and a way to report problems. Ask any prescriber what the risks are, what you should watch for and how to reach them.
Elevren is a hair care service whose dermatologists may prescribe compounded treatments. This article describes published research on one product and does not evaluate any Elevren formulation.
Read how the Elevren assessment works and our privacy policy before you share photos.
Sources
- Piraccini et al., Topical finasteride spray solution for male androgenetic alopecia: a phase III trial, JEADV
- MHRA, Safety review of finasteride: public assessment report
- European Medicines Agency, Measures to minimise risk of suicidal thoughts with finasteride and dutasteride medicines
- US FDA, Potential risks associated with compounded topical finasteride products
Related reading
This article is general information. It is not a substitute for a consultation with a qualified dermatologist.
