Safety information · Internal patient-safety page
Finasteride safety summary
Finasteride 1 mg blocks the conversion of testosterone to dihydrotestosterone (DHT), the hormone driving androgenetic alopecia. Most men see results from 3–6 months of daily use; the effect is dose-dependent and reverses if treatment stops.
What it's used for
- 1 mg orally once a day, with or without food.
- Visible response usually appears at 3–6 months and stabilises by 12 months.
- Stopping treatment reverses the gains within 6–12 months.
- Not licensed for pre-menopausal women; pregnant women should not handle broken or crushed tablets (risk to a male foetus).
Most common side effects
- Decreased libido.
- Erectile dysfunction.
- Ejaculation disorders (reduced ejaculate volume).
- Mild breast tenderness or enlargement.
- Mood changes: including low mood and rarely depressive symptoms.
Serious side effects: stop and seek care
- Persistent sexual side effects after stopping treatment (post-finasteride syndrome): discuss with your doctor.
- Depressive symptoms or suicidal thoughts: stop and seek care.
- Breast lumps, pain or nipple discharge: see your doctor; male breast cancer has been reported.
- Severe allergic reaction (rash, swelling, breathlessness).
Who should not take it
- Women, especially during pregnancy or planning pregnancy: finasteride causes feminisation of male foetuses.
- Children and adolescents under 18.
- Known hypersensitivity to finasteride or any tablet excipient.
- Severe liver impairment: discuss with the doctor before prescribing.
Interactions to flag
- Other 5α-reductase inhibitors (dutasteride): never combine.
- PSA monitoring: finasteride lowers PSA values by ~50%; tell any urologist running a PSA test that you take it.
- Alcohol: large amounts may amplify mood-related effects.
Message us in the app chat if you notice any of these
- Persistent low mood, anxiety or thoughts of self-harm: stop the medicine and contact us same day.
- Sexual side effects that don't settle within a few months or that worry you.
- Any breast change (lumps, pain, discharge).
- Pregnancy in your partner: handling crushed tablets should be avoided.
AEMPS CIMA: Finasteride 1 mg
Back to your consultationThis page summarises information from the regulator-approved leaflet for reference only. It is not medical advice and does not replace the assessment of an EU-licensed doctor. Your doctor will review your individual history, dose and interactions during your consultation.