5-Alpha Reductase Inhibitors
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting, stopping, or changing any medication. Using this site does not create a doctor-patient relationship.
Drug information changes as the FDA updates labeling, and we cannot guarantee it is complete or current. Verify critical details with your pharmacist or physician.
Emergencies: If you think you may have a medical emergency, call 911 immediately. For a suspected overdose, call Poison Control at 1-800-222-1222. Report side effects to the FDA MedWatch program at fda.gov/medwatch or 1-800-FDA-1088.
See our Terms of Use and Editorial Policy.
Overview
Medications that inhibit the conversion of testosterone to dihydrotestosterone (DHT), used for benign prostatic hyperplasia (BPH) to reduce prostate size and for male pattern hair loss (androgenetic alopecia) at lower doses.
How do 5-alpha reductase inhibitors work?
5-alpha reductase inhibitors block the intracellular enzyme 5-alpha reductase, which converts testosterone to the more potent androgen dihydrotestosterone (DHT). Finasteride selectively inhibits the type II isoenzyme found predominantly in the prostate, hair follicles, and liver. By reducing DHT levels, it causes gradual prostatic involution (shrinkage) and, in scalp follicles, reverses miniaturization associated with androgenetic alopecia.
Drugs in this class
- Finasteride (Proscar, Propecia)
- Dutasteride (Avodart)