Dutasteride

Dutasteride is the more potent and broader sibling of finasteride. While finasteride only inhibits 5α-reductase type 2, dutasteride blocks both known isoenzymes - type 1 and type 2. That lowers blood DHT by about 95% (vs ~70% for finasteride).

Clinically approved for benign prostatic hyperplasia (BPH). Used off-label and very widely for androgenetic hair loss - mostly as second choice when finasteride is insufficient.

5α-reductase exists in two isoforms:

• Type 1: mainly in sebaceous glands of the skin and in the liver. NOT inhibited by finasteride.
• Type 2: mainly in prostate, hair follicles and genitals. Inhibited by both finasteride and dutasteride.

Dutasteride inhibits both - hence the stronger DHT reduction. In studies that often produces a better hair effect in patients where finasteride stalls or is too weak.

Oral tablet, once daily or every other day. Time of day doesn't matter.

• 1 tablet with some water.
• With or without food.
• Thanks to the very long half-life dutasteride forgives missed doses better than finasteride.

• Finasteride first: if you've never done anything yet. Gentler, broader experience base.
• Switch to dutasteride: if after 9-12 months of finasteride the hair loss doesn't stop or you clearly want more effect.
• Dutasteride from the start: for very aggressive progression or family history of complete hair loss.

Important: side effect risk is slightly higher with dutasteride because DHT reduction is more complete.

Dutasteride has a smaller but convincing data set:

• Olsen et al. 2006: direct comparison - dutasteride 0.5mg per day was superior to finasteride 5mg per day in hair count.
• Eun et al. 2010: confirmed efficacy of 0.5mg per day in androgenetic hair loss over 6 months.

• Libido loss: somewhat more common than finasteride (about 3-7%), due to stronger DHT suppression.
• Erectile dysfunction: similar frequency.
• Breast tenderness / gynecomastia: rarer but documented.
• Post-finasteride/dutasteride syndrome: very rare, persistent phenomenon after discontinuation.

Due to the 5-week half-life, discontinuation takes unusually long before DHT returns.

• Not for women of childbearing age - teratogenic.
• PSA test is lowered by about 50% on dutasteride - tell your doctor at prostate screening.
• Blood donation only 6 months after stopping - long half-life.

Store dry and protected from light. Keep original container closed, out of reach of children.