Dutasteride
Dual 5-alpha-reductase inhibitor (type I + II). FDA-approved for BPH (Avodart 0.5 mg), off-label for androgenetic alopecia (approved in South Korea/Japan). Reduces serum DHT by ~90-95%, more strongly than finasteride.
Related comparisons
Finasteride vs DutasterideWHAT IS DUTASTERIDE?
Detailed overview
Dutasteride is a synthetic 4-azasteroid developed by GSK (Avodart, FDA approval for BPH in 2001). Unlike finasteride, it inhibits BOTH 5-alpha-reductase isoenzymes (type I + II), thereby reducing serum DHT levels by ~90-95% (vs finasteride ~70%). For androgenetic alopecia it is OFF-LABEL in the USA and the EU, but in South Korea (2009) and Japan (2015) it is officially approved for hair loss at the 0.5 mg dose. According to the phase III dose-ranging study (Gubelin Harcha 2014, PMID 24411083, 917 men), 0.5 mg dutasteride increased hair count and thickness significantly more than finasteride 1 mg or placebo. Due to the exceptionally long ~5-week half-life, the active substance is eliminated slowly and steady state is reached over several months.
ATC code
G04CB02
Prescription status
Prescription (Rx); off-label for AGA
Mechanism of action
Dual 5-alpha-reductase (I + II) inhibition, ~90-95% DHT reduction
Half-life
~5 weeks (terminal) – far longer than finasteride
Onset of action
3-6 months (hair stabilization), 6-12 months (regrowth)
Data console
Lab data
Safety
Side effects, stop signs, contraindications
Side effects · 6
- Sexual side effects: decreased libido, erectile dysfunction and ejaculation disorder (~1-4% each); sometimes slightly more frequent than with finasteride due to the fuller androgen blockade, mostly reversible after discontinuation.
- Breast changes: gynaecomastia, breast tenderness and pain; rarely a breast lump or nipple discharge that must be evaluated.
- Mood disorders: depression and decreased libido reported; a class warning for 5-alpha-reductase inhibitors, discontinue and seek medical advice if psychiatric symptoms occur.
- PSA decreases by ~50%: prostate-specific antigen becomes falsely low, so during prostate cancer screening the measured PSA must be doubled to avoid a false negative.
- Hypersensitivity and skin reactions: rash, pruritus, urticaria, localized edema and (rarely) angioedema; immediate discontinuation if an allergic reaction occurs.
- Slightly increased incidence of high-grade prostate cancer (Gleason 8-10) in the REDUCE trial, while overall prostate cancer risk fell; with no difference in overall survival.
Contraindications · 4
- Pregnancy
- Women of childbearing potential
- Severe hepatic impairment
- Hypersensitivity
Related Hair & Skin
Same therapeutic category
Studies
Related research and clinical findings
A randomized, active- and placebo-controlled study of the efficacy and safety of different doses of dutasteride versus placebo and finasteride in the treatment of male subjects with androgenetic alopecia
Gubelin Harcha W, Barboza Martínez J, Tsai TF, et al.
Superiority of dutasteride over finasteride in hair regrowth and reversal of miniaturization in men with androgenetic alopecia: A randomized controlled open-label, evaluator-blinded study
Shanshanwal SJ, Dhurat RS.
Adverse effects and safety of 5-alpha reductase inhibitors (finasteride, dutasteride): a systematic review
Hirshburg JM, Kelsey PA, Therrien CA, et al.
Telegram
Have a question about Dutasteride?
Educational hair and skin info from official sources (PubMed, FDA, EMA). Does NOT replace medical consultation. Talk to a dermatologist!
Personalized consultation
Want a detailed conversation tailored to your data?
Fill out the prep intake form (your goals, training and health data), and the advisor prepares from it to give genuinely personalized guidance.
Fill out the form~5–7 min · prep questionnaire · confidential · GDPR-compliant
The information here is strictly for educational and scientific purposes. It does not replace medical advice or clinical consultation, and it does not encourage illegal substance or pharmaceutical use. Data is sourced. When in doubt, consult your doctor.