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Dutasteride is a 5-alpha-reductase inhibitor prescribed off-label for post-menopausal hair loss, restricted to patients who can no longer become pregnant. If a doctor has prescribed it for you, this guide covers how to take it safely, what to watch for, and when to contact your doctor.
Receptor-level mechanism. Dutasteride irreversibly inhibits both type 1 and type 2 5α-reductase. Type 2 is the predominant isoenzyme in the inner root sheath of scalp hair follicles and the prostate; type 1 is expressed in the skin’s sebaceous glands and in the outer root sheath [PMID 17110217]. By blocking both isoforms, dutasteride reduces serum dihydrotestosterone (DHT) substantially — in a 24-week dose-ranging study, dutasteride lowered serum DHT dose-dependently to a far greater extent than finasteride 5 mg [PMID 17110217]. Lower DHT in the scalp slows follicular miniaturisation — the progressive conversion of terminal hairs to smaller vellus hairs that characterises androgenetic alopecia.

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How to use

Two rules apply for as long as you are taking it — one about the dose, one about handling the capsule.

Take 0.5 mg once daily as prescribed

Swallow the soft capsule whole, with or without food. Do not chew or open it.

Handle intact capsules only

Dutasteride can pass through skin. Do not touch leaking contents — wash exposed skin immediately with soap and water and ask a pharmacist how to dispose of the capsule.

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Dose schedule

Daily dose 0.5 mg dutasteride — one soft capsule, swallowed whole. Use for female hair loss is off-label.
Take one capsule daily, and do not add finasteride or another dutasteride product. If you miss a dose, skip it rather than doubling up when the next dose is near.
Review at 3–6 months. The doctor reviews the diagnosis, tolerance, breast or mood symptoms, and photographs, to confirm that continued off-label treatment remains appropriate.Hepatic impairment. Dutasteride is extensively metabolised in the liver. In patients with moderate hepatic impairment (Child-Pugh class B), dutasteride exposure is approximately doubled [EMA SmPC]. The reviewing doctor considers this when deciding dose and monitoring frequency.

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Side effects

Contact your doctor if you notice a breast lump, nipple discharge, severe mood change, or persistent sexual symptoms; if a capsule leaks or someone who is pregnant or could become pregnant touches its contents; or if there is any doubt about menopausal status or pregnancy becomes possible.

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Storage

Store below the pack’s temperature limit, commonly 30°C, in the original package to protect from moisture. Keep leaking capsules away from women, children, and adolescents.

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What to expect

Hair treatment is gradual. Early shedding can occur, and photographs taken in the same light are more useful than day-to-day checking. The doctor normally reviews tolerance and progress after several months — continue only while the balance of benefit and risk remains appropriate.

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Common questions

Dutasteride irreversibly inhibits both type 1 and type 2 5α-reductase — the enzymes that convert testosterone to dihydrotestosterone (DHT). Unlike finasteride, which blocks only type 2, dutasteride also suppresses the type 1 isoenzyme found in the skin’s sebaceous glands. In a 24-week randomised trial of 416 men, dutasteride increased target-area hair count in a dose-dependent fashion and 2.5 mg was superior to finasteride 5 mg [PMID 17110217]. Serum DHT suppression is substantially greater with dutasteride than with finasteride [PMID 17110217].
Dutasteride for female hair loss is an off-label use, restricted to post-menopausal patients because of the risk of harm to a male fetus if a woman becomes pregnant. The doctor reviews the diagnosis, tolerance and menopausal status before prescribing.
Breast tenderness or enlargement, reduced libido, mood changes and sexual symptoms can occur. A breast lump, nipple discharge, hives or facial swelling need prompt assessment. Contact your doctor if any of these develop.
Do not add finasteride or another dutasteride product. The doctor may consider combining it with minoxidil as part of a planned regimen — see the oral dutasteride and minoxidil guide.
Skip the missed dose rather than doubling up when the next dose is near. Take one capsule daily as prescribed.
Contact your doctor if you notice a breast lump, nipple discharge, severe mood change or persistent sexual symptoms. Also contact them if a capsule leaks or someone who is pregnant or could become pregnant touches its contents.

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Start a consultation

Hair-growth consultation

Answer the hair-growth questionnaire and a registered doctor reviews it. They decide whether treatment is appropriate, which one, and at what dose — and declining is a normal outcome. See what it costs and how the review works.
This page is reference information, not medical advice and not a prescription. Whether a medicine is appropriate for you is decided by a registered doctor after reviewing your consultation.