Finasteride during transition

Finasteride inhibits the enzyme 5-alpha-reductase, which converts testosterone into the stronger androgen dihydrotestosterone (DHT).

How it works

Finasteride inhibits the enzyme 5-alpha-reductase, which converts testosterone into the stronger androgen dihydrotestosterone (DHT). It is routinely prescribed for benign prostatic hyperplasia and androgenetic alopecia.

Role in feminizing therapy

In transgender healthcare, finasteride is sometimes used as an addition to feminizing hormone therapy to combat hair loss (androgenetic alopecia), not as a primary anti-androgen. International guidelines do not consider it one of the standard anti-androgens.

Side effects and concerns

Known side effects include loss of libido, erectile problems (in people with a penis) and mood-related symptoms. Post-finasteride syndrome is a controversial clinical condition in which symptoms persist after stopping the medication.

Dosage and alternatives

For hair loss, the usual dosage is one milligram per day; for an enlarged prostate, five milligrams. Dutasteride works in the same way and inhibits the enzyme more completely. After removal of the testicles (orchiectomy), the body produces very little testosterone and the medication no longer has a clear purpose. Finasteride can harm a male fetus; pregnant women should therefore not handle broken tablets.

In transgender men

Transgender men who develop hair loss due to testosterone are also sometimes prescribed finasteride. The medication inhibits the conversion responsible for some of the desired masculinization, such as beard growth and clitoral growth. Doctors therefore generally recommend not starting it during the first few years of treatment. See testosterone.

Warnings

In 2025, the European Medicines Agency confirmed that suicidal thoughts can be a side effect of finasteride and had the package leaflet amended. Anyone who becomes depressed while taking it should stop and consult a doctor. Finasteride also lowers the PSA level in the blood, which doctors must take into account when examining the prostate. See hair transplant, spironolactone, cyproterone acetate and side effects of hormones.