Finasteride vs. Dutasteride

See how Finasteride and Dutasteride compare on approved uses, dosing, side effects, and cost.

Key Takeaways

  • Finasteride is FDA-approved for both male pattern hair loss and BPH, while dutasteride is FDA-approved only for BPH and used off-label for hair loss.

  • Dutasteride blocks both type 1 and type 2 5-alpha-reductase, leading to stronger DHT suppression but higher rates of sexual side effects than finasteride.

  • Both drugs lower PSA levels and are unsafe for women who are pregnant or may become pregnant, including through skin contact with broken tablets or capsules.

Finasteride vs. Dutasteride Drug Summary

Finasteride

Finasteride is a 5-alpha-reductase inhibitor available as a low-dose 1 mg tablet for male pattern hair loss and a higher-dose 5 mg tablet for benign prostatic hyperplasia. It works by blocking the enzyme that converts testosterone into DHT and is taken once daily by mouth.

Dutasteride

Dutasteride is a 5-alpha-reductase inhibitor FDA-approved for benign prostatic hyperplasia, taken as a 0.5 mg capsule once daily. It is also widely prescribed off-label for male pattern hair loss because it blocks both forms of the 5-alpha-reductase enzyme.

Finasteride vs. Dutasteride Side Effects

Finasteride

Most common
Decreased libido (1.8%)
Erectile dysfunction (1.3%)
Ejaculation disorder (1.2%)
Breast tenderness/enlargement (<1%)

Dutasteride

Most common
Ejaculation disorders (up to 11% with tamsulosin)
Impotence (erectile dysfunction) (7.3%)
Decreased libido (4%)
Breast disorders (including gynecomastia) (2.2%)

Finasteride vs. Dutasteride Dosage

Finasteride

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 1 mg once daily At the start
Maximum dose 5 mg once daily If needed
Dose changes 1 increase As tolerated

Dutasteride

Dosage
Dosage Table
STAGE DOSE WHEN
Starting dose 0.5 mg once daily At the start
Maximum dose 0.5 mg once daily Same as starting
Dose changes None Fixed dose

Finasteride vs. Dutasteride Indications

Finasteride

Finasteride is approved to treat male pattern hair loss at a 1 mg daily dose and symptoms of an enlarged prostate at a 5 mg daily dose. It works by lowering DHT, the hormone responsible for hair follicle shrinkage and prostate tissue growth. It is not approved for use in women or children.

  • Treats male pattern hair loss (1 mg dose)

  • Treats symptomatic BPH (5 mg dose)

  • Off-label use for hirsutism in women with hyperandrogenism

  • Not approved for women or children

  • No REMS program required

Dutasteride

Dutasteride is FDA-approved to treat symptomatic BPH, either alone or combined with tamsulosin. Off-label, it is widely prescribed for male pattern hair loss because it blocks both type 1 and type 2 5-alpha-reductase enzymes. It is not approved for use in women.

  • Treats symptomatic BPH (0.5 mg dose)

  • Combined with tamsulosin for BPH (Jalyn)

  • Off-label use for male pattern hair loss

  • Not approved for use in women

  • Blocks both types of 5-alpha-reductase

Finasteride vs. Dutasteride Pros and Cons

Finasteride

Finasteride has decades of use for hair loss with a well-established safety profile and broad availability as an affordable generic. Because it blocks only the type 2 5-alpha-reductase enzyme, it may cause somewhat fewer sexual side effects than dual inhibitors for some men. It also clears the body faster if side effects occur.

Pros

  • FDA-approved specifically for hair loss (Propecia)

  • Longer real-world track record (approved since 1992)

  • Clears the body faster, easing reversal of side effects

  • Generally lower rate of sexual side effects than dutasteride

Cons

  • Only partially blocks DHT (type 2 enzyme only)

  • May be less effective than dual inhibition for some men

  • Sexual side effects can persist after stopping

  • Two different dose strengths can cause product confusion

Dutasteride

Dutasteride blocks both type 1 and type 2 5-alpha-reductase, producing deeper and more complete DHT suppression than finasteride. This dual action may make it more effective for hair loss in some men, though that use remains off-label. Its long half-life means side effects and hormone changes can linger for months after stopping.

Pros

  • Blocks both types of 5-alpha-reductase for deeper DHT suppression

  • May work better than finasteride for some men with hair loss

  • Available combined with tamsulosin for BPH (Jalyn)

  • Long half-life may reduce impact of an occasional missed dose

Cons

  • Not FDA-approved for hair loss, only used off-label

  • Higher rates of sexual side effects than finasteride

  • Long half-life means effects linger for months after stopping

  • No dedicated FDA-approved product for hair loss dosing

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