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Safety information · Internal patient-safety page

Dutasteride safety summary

Dutasteride blocks both type-I and type-II 5α-reductase, lowering DHT more completely than finasteride. It is used for androgenetic alopecia in men when a stronger anti-androgen response is appropriate, and for benign prostatic hyperplasia.

Dutasteride 0.5mg

What it's used for

  • 0.5 mg orally once a day, with or without food.
  • Half-life is long (3–5 weeks): plasma levels persist after stopping, side effects can take time to resolve.
  • Stopping treatment reverses hair-loss gains over 6–12 months.

Most common side effects

  • Decreased libido.
  • Erectile dysfunction.
  • Ejaculation disorders.
  • Breast tenderness or enlargement (gynaecomastia).
  • Mood changes: including low mood.

Serious side effects: stop and seek care

  • Depressive symptoms or suicidal thoughts: stop and seek care.
  • Breast lumps, pain or nipple discharge.
  • Severe allergic reaction (angio-oedema).
  • Persistent sexual side effects after stopping treatment.

Who should not take it

  • Women, especially during pregnancy or planning pregnancy: dutasteride causes feminisation of male foetuses and is absorbed through the skin.
  • Children and adolescents under 18.
  • Known hypersensitivity to dutasteride or other 5α-reductase inhibitors.
  • Severe liver impairment.

Interactions to flag

  • Strong CYP3A4 inhibitors (ritonavir, ketoconazole, itraconazole, clarithromycin): can raise dutasteride levels; the doctor may consider an alternate-day schedule.
  • Other 5α-reductase inhibitors (finasteride): never combine.
  • PSA testing: dutasteride lowers PSA by ~50%; tell any clinician running a PSA test you take it.
  • Blood donation: do not donate blood while on dutasteride and for 6 months after stopping.

Message us in the app chat if you notice any of these

  • Persistent low mood or thoughts of self-harm: stop the medicine and contact us same day.
  • Sexual side effects that don't settle within a few months.
  • Any breast change (lumps, pain, discharge).
  • Pregnancy in your partner: capsules should not be handled by pregnant women.
AEMPS CIMA: Dutasteride 0.5 mg

This 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.

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