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Dutasteride (Avodart) — dual 5α-reductase (type I + II) inhibitor
A dual 5α-reductase (type I + II) inhibitor approved for benign prostatic hyperplasia and used off-label for male pattern hair loss. It suppresses DHT more deeply than finasteride (which blocks only type II), and head-to-head it beats finasteride for hair regrowth. It carries the same sexual and mood side-effect concerns as finasteride — with a much longer half-life, so any persistent effects clear more slowly. A prescription drug, not a supplement, and not a longevity drug.
Prescription medication — not a dietary supplement
Dutasteride is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Most Dutasteride studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from high-quality meta-analyses and randomised trials published 2006–2026 with a typical study size of 416 participants.
Based on 61 studies · 14 meta-analyses · 38 RCTs · 26,844 total participants
Confidence
High confidenceBy outcome
Dutasteride has solid randomized evidence: head-to-head superiority over finasteride for hair count (Olsen 2006), a placebo-controlled phase-III hair RCT, the CombAT BPH outcomes trial, and the large REDUCE prostate-cancer-prevention RCT. Network meta-analyses confirm efficacy for androgenetic alopecia. The score is held below the top tier by shared 5ARI sexual side effects, a dutasteride-specific depression signal in meta-analysis, the high-grade-cancer nuance in REDUCE, and its long half-life (slower washout of any persistent effects). It is effective for hair and BPH but is not a longevity drug.
47 rigorous studies
36 randomized trials · 10 meta-analyses · 6 systematic reviews
Our evidence rating for Dutasteride is accountable to this entire body of rigorous research indexed in PubMed — not a hand-picked subset.
PubMed · as of Jul 2026
13 trials ongoing or recruiting · 108 completed on ClinicalTrials.gov
39 of the completed trials have posted results
Registered trials show research momentum for Dutasteride, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Aug 2026
Dutasteride (Avodart) is a dual 5α-reductase inhibitor that blocks both the type-I and type-II isoenzymes that convert testosterone to dihydrotestosterone (DHT).
Finasteride blocks mainly type II; dutasteride blocks both, so it lowers serum and scalp DHT more completely (>90% serum DHT suppression vs ~70% for finasteride).
It is FDA-approved at 0.5 mg/day for benign prostatic hyperplasia (BPH), where the landmark CombAT trial showed it shrinks the prostate, improves urinary symptoms and flow, and reduces the risk of acute urinary retention and BPH-related surgery — more so when combined with the alpha-blocker tamsulosin.
For hair, it is used off-label (approved for androgenetic alopecia in South Korea and Japan, not the US): the Olsen 2006 dose-ranging RCT showed dutasteride 2.5 mg beat finasteride 5 mg for hair count, the dutasteride 0.5 mg phase-III RCT beat placebo, and network meta-analyses rank it among the most effective oral agents for male pattern hair loss.
In the REDUCE prostate-cancer-prevention trial it cut overall prostate-cancer detection by ~23%, but with a small excess of high-grade (Gleason 8–10) tumors in years 3–4 — the nuance that kept it from a cancer-prevention indication.
The honest trade-off: dutasteride is genuinely more potent than finasteride and effective for both BPH and hair, but it shares the class's sexual side effects (reduced libido, erectile dysfunction, ejaculatory problems) and a signal for depression that meta-analysis tied specifically to dutasteride rather than finasteride.
Its terminal half-life is ~5 weeks (vs ~6–8 hours for finasteride), so it accumulates and washes out slowly — relevant to anyone worried about persistent, post-finasteride-syndrome-type effects. It is a prescription drug, not a supplement, and there is no evidence it extends lifespan.
Blocks both isoenzymes that convert testosterone to DHT — unlike finasteride, which blocks mainly type II — producing deeper (>90%) serum and scalp DHT suppression.
Lower scalp DHT slows follicle miniaturization (hair benefit); lower prostate DHT shrinks the gland (BPH benefit).
Dutasteride accumulates and clears slowly — far longer than finasteride's ~6–8 hours — so DHT suppression and any persistent effects wash out slowly.
How Dutasteride works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Contraindicated — do not handle leaking capsules; absorbed through skin and can harm a male fetus.
Defer blood donation for at least 6 months after the last dose (long half-life; protects a potential pregnant recipient).
Caution — discuss the class side-effect profile and dutasteride-specific depression signal before starting.
Tell your clinician — 5ARIs lower PSA ~50%; interpret screening accordingly.
Can raise dutasteride levels; the long half-life already favors accumulation.
Combined intentionally for BPH (CombAT); additive effect on urinary symptoms, monitor blood pressure.
Tip: Often improves with continued use or after stopping; discuss with a clinician.
Tip: Shared 5ARI class effect; weigh against benefit. May persist in a minority; long half-life slows resolution.
Tip: Meta-analysis tied a depression signal specifically to dutasteride; monitor mood and stop if it emerges.
Tip: Report new breast lumps; rarely a sign of male breast cancer.
Tip: 5ARIs roughly halve PSA — double the reading for screening; REDUCE showed a small excess of Gleason 8–10 tumors.
Dutasteride has an evidence score of 5.4/10 — moderate evidence based on 53 indexed studies, including 3 meta-analyses. A dual 5α-reductase (type I + II) inhibitor approved for benign prostatic hyperplasia and used off-label for male pattern hair loss. It suppresses DHT more deeply than finasteride (which blocks only type II), and head-to-head it beats finasteride for hair regrowth. It carries the same sexual and mood side-effect concerns as finasteride — with a much longer half-life, so any persistent effects clear more slowly. A prescription drug, not a supplement, and not a longevity drug. Representative study: PMID 23768246.
The commonly studied dose of Dutasteride is Approved BPH dose is 0.5 mg once daily; off-label hair-loss use mirrors the same 0.5 mg once-daily dose under a clinician. A prescription drug.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
The best time to take Dutasteride is in the morning. It can be taken on an empty stomach. Once daily, with or without food.
Dutasteride should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are decreased libido, erectile / ejaculatory dysfunction, depressed mood. Use caution if any of these apply to you: Women who are or may become pregnant (risk to a male fetus — DHT is required for male genital development); Children; Known hypersensitivity to dutasteride or other 5α-reductase inhibitors.
Finasteride
Mostly mechanism / observationalA prescription 5α-reductase type-II inhibitor that lowers DHT to treat male pattern hair loss (1 mg, Propecia) and benign prostatic hyperplasia (5 mg, Proscar). The hair and prostate benefits are well-proven in large RCTs. The honest caveats are real and prominent: sexual side effects (erectile dysfunction, decreased libido) in a minority of men, a disputed but important 'post-finasteride syndrome' with persistent symptoms, and a depression/suicidality safety signal in pharmacovigilance data. It is NOT a longevity drug.
Beta-Sitosterol
Likely helpsPlant sterol that reduces BPH urinary symptoms in clinical trials and blocks intestinal cholesterol absorption.
Minoxidil (oral & topical)
Mostly mechanism / observationalA potassium-channel-opening vasodilator — originally an oral antihypertensive — whose well-documented hypertrichosis side effect made it the first FDA-approved hair-loss drug. Topical 2–5% (Rogaine) is OTC and proven in androgenetic alopecia; low-dose ORAL minoxidil (LDOM, ~0.25–5 mg) is an off-label, rapidly adopted alternative with real but generally mild cardiovascular/hypertrichosis side effects. A drug, not a supplement — and not a longevity compound.
Testosterone (TRT)
Mostly mechanism / observationalThe primary male androgen and an FDA-approved prescription drug for diagnosed male hypogonadism — and a Schedule III CONTROLLED SUBSTANCE. For men with genuinely low testosterone, randomized trials show real benefits: the Testosterone Trials (TTrials) improved sexual function, mood, anemia and bone density in older hypogonadal men, and the large TRAVERSE trial found TRT non-inferior to placebo for major cardiac events. But those benefits were modest and indication-specific, NOT a longevity or anti-aging result. It is prescription-only; non-medical, supraphysiologic, and 'anti-aging' use is illegal and carries serious harms — erythrocytosis, suppressed sperm production/fertility, cardiovascular and psychiatric risk. This is a harm-reduction reference, not a recommendation, and testosterone is NOT a dietary supplement.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 61 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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