Comparison
Finasteride vs Dutasteride
Dutasteride improved hair counts more in one major trial; safety and suitability need separate assessment.
Comparison summary
A 24-week randomized trial found greater hair-count improvement with oral dutasteride 0.5 mg daily than oral finasteride 1 mg daily in men with androgenetic alopecia. That finding does not establish a universally safer drug, a guaranteed response after switching, or a self-treatment schedule. The study doses identify the trial arms. Gubelin Harcha and colleagues, original abstract.
Evidence reviewed September 29, 2026. US labeling approves Propecia for male pattern hair loss; Avodart's US indication is benign prostatic hyperplasia, so hair-loss use is off-label in the US. Approval varies by jurisdiction. Propecia label, Avodart label.
The dose tiers and effectiveness graphics below are site reference fields, not clinical recommendations or a validated beginner-to-advanced progression. They do not replace a prescription, identify a safe dose for an individual, or establish protection during anabolic-steroid use.
Finasteride
5α-Reductase Inhibitor (Type II/III)
Dutasteride
Dual 5α-Reductase Inhibitor
Effectiveness Profile
At a Glance
| Finasteride | Dutasteride | |
|---|---|---|
| Type | Hair | Hair |
| Legal status | Rx-Only | Rx-Only |
| Half-life | 5–6HR (plasma) | ~5WK |
| Preferred route | Oral | Oral |
| Dose frequency | once-daily | once-daily |
| Beginner dose | 0.25–1 mg | 0.5–1 mg |
| Intermediate dose | 1–1.25 mg | 1.5–3.5 mg |
| Advanced dose | 1–1.25 mg | 3.5–3.5 mg |
| Cycle length | 52–520 wks | 24–260 wks |
| Bioavailability | 72% | 60% |
| Time to peak | 1.5h | 2.5h |
| Active duration | 48h | 840h |
| Storage | 20–25°C | 15–30°C |
| PCT required | No | No |
| Ancillaries required | No | No |
| Safe for women | No | No |
Verdict
What the direct trial supports#
Gubelin Harcha's 2014 trial randomized 917 men aged 20–50 to three dutasteride doses, finasteride or placebo. At 24 weeks, the dutasteride 0.5 mg arm had greater target-area hair count and width than the finasteride 1 mg arm, with better frontal photographic assessment. The abstract reports similar numbers and severity of adverse events across groups. Its 24-week duration cannot resolve uncommon or persistent harms, and it was not a trial specifically of people who had failed finasteride. Full subscription text was unavailable for this review. Original study.
Drug persistence is different from symptom recovery#
The Propecia label gives a plasma half-life of approximately 5–6 hours in men aged 18–60. Avodart has a terminal half-life of about five weeks at steady state and can remain detectable for four to six months after stopping. Those pharmacokinetic differences matter, but neither provides a deadline for recovery from adverse effects. Finasteride's label includes reports of sexual dysfunction continuing after discontinuation and male infertility or poor seminal quality; voluntary reports do not supply a reliable incidence. Avodart also warns that sexual adverse reactions may persist after stopping, while its role in that persistence is unknown. Its labeling reports reductions in semen measures in a small study and says the significance for an individual's fertility is unknown. Propecia prescribing information, Avodart prescribing information.
Safety cannot be ranked from potency alone#
The May 2026 MHRA update reinforces finasteride warnings about psychiatric effects and sexual dysfunction, which may persist after stopping. Dutasteride's mood warning is precautionary: the regulator describes very limited dutasteride data. The EMA review confirmed suicidal thoughts as a finasteride-tablet adverse effect of unknown frequency, while finding insufficient evidence to establish that causal link for dutasteride. These different evidence levels do not prove dutasteride risk-free or finasteride universally safer. MHRA update, EMA review.
Intermittent dosing has limited, specific evidence#
A 2025 pilot randomized 60 men to twice-weekly dutasteride, thrice-weekly dutasteride or daily finasteride for 24 weeks. Hair measures improved, but participants were unblinded and there was no daily-dutasteride group. Recent oral-finasteride users were excluded. This cannot establish that intermittent dosing equals daily dutasteride, reliably prevents sexual effects or supplies a switching protocol. A long half-life alone cannot answer those questions. Full pilot study.
Pick A or B?
Questions to take to the prescriber#
- If treatment appears ineffective: confirm the diagnosis, duration, adherence and how change was measured before interpreting it as treatment failure. Read the finasteride-to-dutasteride switching evidence; the trial advantage does not predict every person's outcome.
- If fertility or pregnancy exposure matters: discuss this before treatment. Neither drug can be selected as a guaranteed fertility-preserving option. Follow the product's pregnancy and handling precautions, including those concerning broken finasteride tablets and dutasteride capsules. The labels also require care when interpreting PSA results.
- If psychiatric or sexual symptoms develop: follow the current safety advice. The MHRA advises stopping finasteride 1 mg and contacting a clinician promptly for depression or suicidal thoughts; for finasteride 5 mg or dutasteride, contact the clinician promptly. Sexual symptoms also warrant medical advice. Seek emergency help if there is immediate danger. MHRA patient instructions.
- If considering a topical substitute: evidence is formulation-specific. See our topical versus oral finasteride review and topical dutasteride review. A different route does not automatically remove systemic risks.
Any product listings on this page are separate commercial information. Research-grade products are not substitutes for prescribed medicines.