What it is
Dutasteride is an oral medication that inhibits both type I and type II 5-alpha reductase enzymes, resulting in greater DHT suppression than finasteride (which inhibits only type II). It is FDA-approved for benign prostatic hyperplasia but prescribed off-label for androgenetic alopecia.
Who it's commonly prescribed for
Dutasteride is generally considered for men who have not responded adequately to finasteride, or in cases where a clinician determines that greater DHT suppression may be beneficial. It is not typically a first-line treatment due to its broader enzyme inhibition and longer half-life (weeks).
Typical timeline
Clinical improvement generally follows a similar trajectory to finasteride: reduced shedding within 3 months, visible changes at 6 to 12 months, and maximum effect around 24 months. Due to its long half-life, both therapeutic effects and side effects may take longer to resolve after discontinuation.
Common side effects
Dutasteride shares a similar side-effect profile with finasteride, though rates may be modestly higher due to greater DHT suppression.
- Decreased libido
- Erectile changes
- Reduced ejaculate volume
- Breast tenderness or enlargement
- Mood changes
- Longer washout period after discontinuation
Questions to ask a clinician
Given that dutasteride is off-label for hair loss, a thorough discussion is recommended.
- Why dutasteride rather than finasteride for my situation?
- What does the evidence say about dutasteride for hair loss specifically?
- How does the longer half-life affect my options if I want to stop?
- Are there additional lab tests I should have before starting?
- What is the plan if I experience side effects?
- How will we measure whether this is working for me?