Finasteride and dutasteride are the two main prescription DHT blockers used for male pattern hair loss. They work the same basic way but differ in how broadly they act, how long they stay in the body, and how much evidence and regulatory approval each has for hair loss. This guide compares them side by side. For topical versions, see our guide to topical dutasteride vs finasteride.
How DHT blockers work
Male pattern hair loss (androgenetic alopecia) is driven largely by dihydrotestosterone, or DHT. The body makes DHT from testosterone using an enzyme called 5-alpha reductase. In people whose follicles are sensitive to DHT, follicles gradually shrink and produce thinner, shorter hairs, a process called miniaturization.
Finasteride and dutasteride are both 5-alpha reductase inhibitors. By blocking the enzyme, they lower DHT. Read more about how finasteride works.
Finasteride
Finasteride mainly blocks the type 2 form of 5-alpha reductase, the form found in hair follicles and the prostate. Oral finasteride has been FDA-approved for male pattern hair loss since 1997, so it has decades of clinical data behind it. It clears from the body within hours, which is why it is taken continuously when prescribed.
Dutasteride
Dutasteride blocks both type 1 and type 2 forms of the enzyme and lowers blood DHT levels more than finasteride in studies of the oral forms. In the United States it is FDA-approved for an enlarged prostate, and its use for hair loss is off-label. It has been approved for hair loss in some other countries, including South Korea and Japan. Dutasteride stays in the body for weeks, which matters for side effects and for certain precautions.
Side-by-side comparison
| Finasteride | Dutasteride | |
|---|---|---|
| Enzyme types blocked | Mainly type 2 | Types 1 and 2 |
| Effect on blood DHT | Lowers it | Lowers it further |
| Time in the body | Hours | Weeks |
| US FDA status for hair loss | Approved (oral) | Off-label |
| Evidence for hair loss | Extensive | Growing |
What the research shows
A 2024 systematic review comparing the two found greater increases in hair count with dutasteride than with finasteride in the studies it analyzed, and a broadly similar rate of side effects (PubMed). Those studies were mostly of oral forms, and individual responses vary widely. A stronger effect on DHT does not automatically make dutasteride the right choice for a given person. Its longer half-life and off-label status are part of the decision.
Side effects and safety
Both medications can cause sexual side effects, such as reduced libido or erectile difficulties, and mood changes have been reported. Some people report symptoms that persist after stopping finasteride. Because dutasteride remains in the body for weeks, side effects may take longer to resolve after it is stopped.
- People who are pregnant or may become pregnant must not take or handle either medication, because both can cause birth defects in a male fetus.
- Both lower PSA, a prostate cancer screening test. Tell any doctor ordering that test.
- Blood donation is restricted while taking these medications, and for longer after dutasteride.
- Liver conditions and other medications need to be reviewed first.
Report any side effects to your provider, and do not start, stop or switch either medication on your own.
Switching from finasteride to dutasteride
Some patients ask about switching when they feel finasteride is not doing enough. Whether that makes sense, and how any change should be made, is a decision for your provider after reviewing your history and your response so far. Hair changes slowly, so providers typically evaluate response over months rather than weeks before considering a change.
Compounded, personalized formulas
A provider may prescribe either medication on its own, or as part of a compounded formula prepared by a licensed pharmacy for an individual patient, sometimes combined with other ingredients such as minoxidil. Read about finasteride and minoxidil together. Compounded medications are not FDA-approved.
Frequently asked questions
Is dutasteride better than finasteride?
It lowers DHT more and performed better on hair count in a recent review of mostly oral studies. It also stays in the body far longer and is off-label for hair loss in the US. Which is appropriate depends on your situation.
Why is finasteride usually prescribed first?
Oral finasteride is FDA-approved for male pattern hair loss and has a longer record of use for that purpose.
Can women use these medications?
They are not appropriate for anyone who is or may become pregnant. Any use in women is a specialist decision made case by case.
Next step
A licensed provider can review your history and decide whether either option is appropriate for you. Start your online consultation.
Prescription required. A licensed provider decides whether treatment is appropriate. Compounded medications are prepared by a licensed pharmacy for an individual patient and are not FDA-approved. Individual results vary. Prescribed Essence currently serves patients in California, Colorado, Florida and New York.
