Dutasteride

A stronger cousin of finasteride. Blocks more DHT, and is used off-label in the US when finasteride is not enough.

Moderate evidencePrescription

The cheapest legitimate way

Needs a prescription, and in the US it is off-label for hair loss, so ask a dermatologist. Generic 0.5 mg capsules are cheap at discount pharmacies.

Smart path~$10–$20/mo generic + prescription visit

Prices are estimates based on typical US cash prices. They change often, so check before you buy.

Evidence: Moderate. Supported by smaller trials or growing clinical use.
How it works: Finasteride blocks one of the two enzymes that make DHT. Dutasteride blocks both, so it lowers DHT further. It is approved for hair loss in South Korea and Japan, and for an enlarged prostate in the US.
What results look like: In a head-to-head trial, 0.5 mg dutasteride grew more hair than 1 mg finasteride at 24 weeks. Long-term hair loss data is thinner than for finasteride.
Time to results: Judge results at 6–12 months.
Side effects and downsides: Sexual side effects similar to finasteride, possibly slightly more common
Stays in the body for months after stopping, so side effects can take longer to fade
Lowers PSA (a prostate cancer screening test) by about half. Tell your doctor you take it
Do not donate blood until 6 months after your last dose
Best for: Men still losing hair on finasteride, after a conversation with a dermatologist.
Sources: Gubelin Harcha et al., 2014, J Am Acad Dermatol (dutasteride vs finasteride)
Olsen et al., 2006, J Am Acad Dermatol (dutasteride dose-ranging)
FDA Avodart (dutasteride) prescribing information

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