Finasteride

Finasteride is a selective inhibitor of the enzyme 5α-reductase type 2 - the enzyme that converts testosterone into DHT (dihydrotestosterone). DHT is the main driver of androgenetic hair loss: it binds to hair follicle receptors and gradually miniaturizes the follicles.

Finasteride lowers blood DHT by about 70% and has been the oral gold standard against hereditary hair loss for decades.

5α-reductase type 2 sits in skin, prostate, testes and elsewhere. Finasteride selectively blocks this enzyme, reducing:

• Plasma DHT: drops about 70%.
• Scalp DHT: drops about 60-65% - the key effect for the hair.
• Plasma testosterone: stays nearly unchanged or rises slightly (more T doesn't enter the DHT pathway).

Result at the follicles: miniaturization stops, in many cases shrunk follicles grow back to normal size.

Oral tablet, once per day. Time of day doesn't matter.

• 1 tablet (1mg) with some water.
• With or without food.
• A fixed daily routine is important - gaps weaken the effect.

Finasteride has one of the best data sets of any hair loss therapy:

• Kaufman et al. 1998: 5-year study with 1879 men - 90% stable or improved hair status on 1mg daily.
• Olsen et al. 1999: long-term efficacy and safety confirmed, plus moderate re-growth in about 65% of users.

These studies are the basis for worldwide approval.

• Libido loss: reported by about 1-4% of users. Usually reversible.
• Erectile dysfunction: similar frequency.
• Mood changes: less common but documented.
• Post-Finasteride Syndrome (PFS): very rare, controversial phenomenon with persistent symptoms after discontinuation. The data is hard to interpret.

If concerned: start low (0.5mg every other day), observe and decide whether to step up.

• Not for women of childbearing age - finasteride is teratogenic, can harm male fetuses.
• PSA test is lowered by about 50% on finasteride - tell your doctor at prostate screening.
• Effect is not curative - stopping returns the hair loss.

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