Dutasteride 0.5 mg: an enlarged-prostate drug used off-label for hair loss
Dutasteride is a daily capsule that blocks both forms of the enzyme that makes dihydrotestosterone (DHT). In the US the FDA approves it for symptomatic benign prostatic hyperplasia (BPH), not for hair loss. Physicians prescribe it off-label for male pattern hair loss, and it stays in the body for months after the last capsule, so the decision deserves care.
Information current as of November 10, 2026. Educational only. Confirm everything here with your own clinician before starting, stopping or changing any medication.
At a glance
Drug class
5-alpha-reductase inhibitor that blocks both the type 1 and type 2 forms of the enzyme. Finasteride blocks type 2 only.
How it is taken
A 0.5 mg soft gelatin capsule by mouth. The label dose for BPH is one capsule once daily. The label gives no hair loss dose.
Approval status
FDA-approved (Avodart and generics) for symptomatic BPH. Male pattern hair loss is off-label in the US. Japan and South Korea have approved it for male hair loss.
Who it is for
Adult men whom a physician judges a fit after history and labs. It is not for women or children.
Main cautions
Sexual and breast side effects, lower PSA readings, reports of depressed mood, no blood donation for 6 months after the last dose, and harm to a male fetus if a pregnant woman handles capsules.
What it is
How dutasteride works, and why it differs from finasteride
Male pattern hair loss runs in families. In men who carry the genes, scalp follicles are sensitive to DHT, which shortens each hair growth cycle until the hair is thin and short. Both dutasteride and finasteride lower DHT. They do it differently.
The finasteride label explains that type 2 5-alpha-reductase makes about two-thirds of circulating DHT and type 1 makes about one-third. Finasteride blocks type 2. The Avodart label describes dutasteride as a selective inhibitor of both type 1 and type 2. The type 1 enzyme is common in scalp skin and sebaceous glands, which is the reason physicians became interested in dutasteride for hair.
The effect on DHT is large. The Avodart label reports that 0.5 mg daily cut median serum DHT by 85% after one week and 90% after two weeks. In men with BPH followed for four years, the median fall was 93% to 95%. Median testosterone rose by 19% to 26%, and stayed within the physiologic range.
Dutasteride does not remove the genetic tendency toward thinning. It reduces one of the hormones that drives it. If DHT suppression ends, the thinning resumes.
Approval status
What the FDA approved it for, and what is off-label
The Avodart label lists one use: treatment of symptomatic BPH in men with an enlarged prostate. It is meant to improve symptoms, lower the risk of acute urinary retention and lower the risk of BPH-related surgery, alone or with the alpha blocker tamsulosin. The label also says it is not approved to prevent prostate cancer.
Hair loss is an off-label use in the US
No dutasteride product is FDA-approved for male pattern hair loss. A 2022 review reports that Japan and South Korea have approved oral dutasteride 0.5 mg for male androgenetic alopecia (Korea in 2009, per a 2024 Korean study). Those approvals do not apply in the US. Off-label prescribing is legal and common, and it means the physician is using judgment beyond the label.
Finasteride 1 mg is the FDA-approved hair loss option in this drug family. If you want the on-label choice, see our finasteride page. A topical or low-dose oral alternative is covered on our minoxidil page.
Who it is for
Who might be a fit, and who is not
A physician should confirm the pattern first. Thyroid disease, low iron, scalp conditions and some medicines also thin hair, and none of those respond to a 5-alpha-reductase inhibitor. The shedding that follows rapid weight loss is a different process; see our post on hair loss and GLP-1 medicines.
- Not for women. The label says it is not indicated for use in women, and it is contraindicated in pregnancy.
- Not for children. Safety and effectiveness in pediatric patients have not been established.
- Not for anyone who has had a serious allergic reaction to dutasteride or another 5-alpha-reductase inhibitor, such as angioedema or a serious skin reaction.
- Extra thought if you have had depression or anxiety, any sexual problem, or a family history of prostate or breast cancer.
- Extra thought if you and a partner are trying to conceive, because the label reports an effect on sperm count.
The label gives one dose, 0.5 mg once daily for BPH. It does not describe a hair loss dose, and we do not give dosing advice on this page. Dr. Miranda sets the plan for you individually.
The evidence
What the hair loss trials show
The strongest comparison is a 2014 phase 3 trial in 917 men aged 20 to 50 with androgenetic alopecia (Gubelin Harcha 2014). Men received dutasteride 0.02, 0.1 or 0.5 mg daily, finasteride 1 mg daily, or placebo for 24 weeks. Hair count and hair width rose in a dose-dependent way with dutasteride. At 24 weeks, dutasteride 0.5 mg gave a larger gain in hair count and width than finasteride 1 mg (P = .003 and P = .004) and a stronger panel-rated photographic result in the frontal view (P = .002). The authors reported similar numbers and severity of adverse events across groups. The study lasted only 24 weeks.
An earlier study randomized 416 men aged 21 to 45 to dutasteride 0.05, 0.1, 0.5 or 2.5 mg, finasteride 5 mg, or placebo for 24 weeks (Olsen 2006). Dutasteride raised hair counts in a dose-dependent way versus placebo. The abstract names only the 2.5 mg dose as outperforming finasteride at 12 and 24 weeks. That dose is five times the label dose. The finasteride arm used 5 mg, not the 1 mg hair loss dose.
A 2014 network meta-analysis pooled randomized trials of finasteride 1 mg and 5 mg and dutasteride 0.5 mg (Gupta 2014). It found the active treatments were not significantly different from each other in efficacy. A 2022 review ranked dutasteride 0.5 mg first for efficacy, but rankings like that rest on indirect comparisons across different trials, so treat them as a rough guide. Trials in different populations are not directly comparable.
Long-term evidence is thin. The main one is a Korean retrospective review of 99 men who stayed on dutasteride 0.5 mg for at least five years (2024 Korean review). Physicians rated 89.9% as improved and 93.9% as not progressing. Patients who stay on a drug for five years are a self-selected group, and the review had no control arm.
What this means in practice
Dutasteride 0.5 mg increased hair counts more than finasteride 1 mg over 24 weeks in one large trial. Nobody has shown that this holds over years, or that the extra effect is worth the extra DHT suppression for every man. Results vary, the effect is gradual, and no one can promise how much hair you will keep or regain.
Side effects
Sexual, breast and mood effects
The Avodart label lists impotence, decreased libido, ejaculation disorders and breast disorders (enlargement and tenderness) as the most common adverse reactions. Those rates come from BPH trials in men with a mean age of 66, not from hair loss trials in younger men. In the first six months of the pooled two-year trials, impotence was 4.7% on dutasteride versus 1.7% on placebo, decreased libido 3.0% versus 1.4%, and ejaculation disorders 1.4% versus 0.5%. Rates fell in later months. Breast disorders were 0.5% versus 0.2% early on, and 1.1% versus 0.3% at months 13 to 18.
A 2019 meta-analysis of 15 randomized hair loss trials (4,495 men) found a 1.57-fold risk of sexual dysfunction with 5-alpha-reductase inhibitors overall (Lee 2019). For finasteride the relative risk was 1.66. For dutasteride it was 1.37, with a confidence interval of 0.81 to 2.32 that crosses 1. The authors said the dutasteride studies were too few to draw a firm conclusion.
The label states that these sexual adverse reactions may persist after treatment stops, and that the role of dutasteride in that persistence is unknown. If you notice any change in erections, libido or ejaculation, tell your physician early. Erectile function has its own treatments; see our tadalafil page.
Mood. The label lists depressed mood among postmarketing reports. These reports come from a group of unknown size, so a cause and a rate cannot be established. A 2024 meta-analysis of five observational studies and more than 2.2 million patients found no statistically significant link between 5-alpha-reductase inhibitors and depression (adjusted hazard ratio 1.30, confidence interval 0.85 to 2.00) or suicide (1.30, 0.65 to 2.61) (Uleri 2024). A wide interval does not rule out a small risk. If your mood drops after starting, stop the capsule and contact your physician. In a crisis, call or text 988.
Fertility. In a label study of healthy men, 52 weeks of dutasteride lowered total sperm count by 23% after adjusting for placebo, and the count was still 23% below baseline 24 weeks after stopping. Values stayed in the normal range. The label says the clinical meaning for an individual man’s fertility is not known.
Warnings
PSA, prostate cancer and breast cancer
Dutasteride lowers prostate-specific antigen (PSA). The label says it cut serum PSA by about 50% within 3 to 6 months. To read a single PSA in a man treated for 3 months or more, double it before comparing it with normal values for untreated men. A new baseline should be set at least 3 months after starting. Any confirmed rise from your lowest value should be evaluated, even if the number still falls in the normal range. Tell every physician who orders a PSA that you take it.
The label warns of a higher rate of high-grade prostate cancer. In REDUCE, a 4-year trial of 8,231 men aged 50 to 75 with a PSA of 2.5 to 10 ng/mL and a prior negative biopsy, Gleason score 8 to 10 cancer was found in 1.0% on dutasteride and 0.5% on placebo. The label says the cause is not established, and notes a similar finding with finasteride 5 mg in a different trial. This was in an older group at risk for prostate cancer, not young men with hair loss.
Male breast cancer appears in the label’s postmarketing reports. In the pivotal BPH trials there was one case in the dutasteride group and one in the placebo group, and the label says the relationship between long-term use and male breast neoplasia is unknown. Report a breast lump, pain or nipple discharge to your physician promptly.
Safety
Pregnancy, handling the capsules and blood donation
Dutasteride blocks the DHT a male fetus needs to form normal external genitalia. The label contraindicates its use in pregnancy and says women who are pregnant or may be pregnant should not handle the capsules. It can be absorbed through the skin. If a pregnant woman touches a leaking capsule, she should wash the area with soap and water right away.
Keep capsules sealed and out of reach of a partner who is or may be pregnant.
The label says men taking it should not donate blood until at least 6 months after the last dose. The reason is to avoid giving dutasteride to a pregnant transfusion recipient.
The drug stays for months
- The terminal half-life is about 5 weeks. Serum levels reach about 90% of steady state after 3 months of daily use.
- After the last dose, levels remain detectable for up to 4 to 6 months, per the label.
- That is why a side effect may take months to fade, why the effect on PSA outlasts the last capsule, and why the blood donation wait is 6 months.
- Finasteride clears far faster. A 2022 review gives its half-life as about 4.5 hours, against about 5 weeks for dutasteride.
Monitoring and stopping
Labs, interactions and what happens when you stop
Dutasteride is broken down mainly by the liver enzymes CYP3A4 and CYP3A5. The label says to use caution with potent, long-term CYP3A4 inhibitors such as ritonavir, because that interaction has not been studied. Give your physician your full medicine and supplement list.
Because the drug changes PSA readings, a physician may want a PSA before you start. Tell your physician about any breast changes, mood changes or sexual changes at each check-in.
If you stop, the hair benefit is not expected to last. DHT suppression fades over months because of the long half-life, and the hair that the drug was holding is gradually lost again. Some men report sexual or mood symptoms that last after stopping; tell your physician if that happens. A man who stops should keep avoiding blood donation for 6 months and should tell his physician before his next PSA.
Testosterone therapy is a separate question, because 5-alpha-reductase inhibition changes how androgens act on the scalp and prostate. Read our testosterone page and discuss any combination with your physician.
Summit’s role
What Summit does with dutasteride
Dr. Miranda decides whether dutasteride fits you after your history and labs. That review covers your hair pattern, medicines, sexual and mood history, family history, and a PSA when it applies. He may recommend finasteride, minoxidil or neither instead.
- Summit is telehealth only. If a prescription is written, it goes to a pharmacy that fills it. Summit does not dispense or sell dutasteride.
- Hair loss is an off-label use in the US, and Dr. Miranda will say so when he discusses it.
- We will not prescribe it to women, to children, or to anyone who is or may be pregnant.
- Costs are on our pricing page. Individual results vary.
Common questions
Questions people ask
Is dutasteride FDA-approved for hair loss?
No. In the US the FDA approves dutasteride (Avodart) for symptomatic benign prostatic hyperplasia. Using it for male pattern hair loss is off-label. Japan and South Korea have approved it for male hair loss, but those approvals do not apply in the US.
How is dutasteride different from finasteride?
Finasteride blocks type 2 5-alpha-reductase. Dutasteride blocks type 1 and type 2, so it lowers DHT further. In one 24-week trial of 917 men, dutasteride 0.5 mg increased hair count more than finasteride 1 mg. It also stays in the body for months, while finasteride clears in hours.
Can dutasteride cause sexual side effects?
Yes. The label lists impotence, decreased libido, ejaculation disorders and breast enlargement or tenderness as the most common reactions, and says they may continue after stopping. The role of the drug in that persistence is unknown. Tell your physician early if you notice any change.
Will dutasteride affect my PSA test?
Yes. It lowers PSA by about 50% within 3 to 6 months. The label says to double the value when interpreting a single result after 3 months or more on the drug. Any confirmed rise from your lowest number should be evaluated, even if it is still in the normal range.
Can my partner handle the capsules if she may be pregnant?
No. The label says women who are pregnant or may be pregnant should not handle the capsules, because the drug can be absorbed through skin and can harm a male fetus. If she touches a leaking capsule, she should wash the area with soap and water right away.
Can I donate blood while taking it?
No. The label says men treated with it should not donate blood until at least 6 months after the last dose. Because the half-life is about 5 weeks, the drug stays in the blood for months after the last capsule.
What happens when I stop?
Levels fall slowly and stay detectable for up to 4 to 6 months, so effects fade over months. The hair benefit is not expected to last without the drug, and thinning gradually resumes. If sexual or mood symptoms continue after you stop, tell your physician.
Sources
Where this comes from
All retrieved November 10, 2026.
- Waylis Therapeutics. AVODART (dutasteride) capsule, liquid filled, prescribing information. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=960797b3-09b1-4d6a-8ece-8b5d918e93e4
- Organon. PROPECIA (finasteride) tablet, prescribing information. DailyMed. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6f904709-65aa-44ce-b144-b4c8a0416e36
- Gubelin Harcha W, et al. 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. J Am Acad Dermatol 2014. https://pubmed.ncbi.nlm.nih.gov/24411083/
- Olsen EA, et al. The importance of dual 5alpha-reductase inhibition in the treatment of male pattern hair loss: results of a randomized placebo-controlled study of dutasteride versus finasteride. J Am Acad Dermatol 2006. https://pubmed.ncbi.nlm.nih.gov/17110217/
- Gupta AK, et al. The efficacy and safety of 5alpha-reductase inhibitors in androgenetic alopecia: a network meta-analysis and benefit-risk assessment of finasteride and dutasteride. J Dermatolog Treat 2014. https://pubmed.ncbi.nlm.nih.gov/23768246/
- Lee S, et al. Adverse sexual effects of treatment with finasteride or dutasteride for male androgenetic alopecia: a systematic review and meta-analysis. Acta Derm Venereol 2019. https://pubmed.ncbi.nlm.nih.gov/30206635/
- Uleri A, et al. Association of 5alpha-reductase inhibitors with depression and suicide: a mini systematic review and meta-analysis. Eur Urol Focus 2024. https://pubmed.ncbi.nlm.nih.gov/38692949/
- Long-term efficacy and safety of dutasteride 0.5 mg in Korean men with androgenetic alopecia: 5-year data. J Dermatol 2024. https://pubmed.ncbi.nlm.nih.gov/38321615/
- Comparison of oral minoxidil, finasteride, and dutasteride for treating androgenetic alopecia. J Dermatolog Treat 2022. https://pubmed.ncbi.nlm.nih.gov/35920739/
Confirm with your provider. This page is general education, not medical advice, and it does not diagnose or treat anything. Every medication carries risks and is not right for everyone. Medication is prescribed only after a physician evaluation determines it is appropriate for you. Individual results vary and no outcome is guaranteed. Information current as of November 10, 2026.
Next step
Thinning hair and want a physician’s opinion?
Apply and Dr. Miranda will review your history and labs first, then tell you honestly whether dutasteride, finasteride, minoxidil or neither is a fit.