Glossary

Minoxidil

A topical or oral medication that prolongs the anagen growth phase of hair follicles. FDA-approved as a 5% topical for androgenetic alopecia; widely used off-label as a 0.25 to 5 mg/day oral tablet.

Also: Rogaine

Minoxidil is a vasodilator originally developed for severe hypertension; the hair-growth side effect was noticed and led to its repurposing for androgenetic alopecia.

The mechanism is incompletely understood. Minoxidil prolongs the anagen (growth) phase of the hair cycle, increases follicle size, and may improve dermal papilla blood flow. It works on top of any existing genetic hair-loss process; it does not lower DHT.

Two main forms:

Topical 5% solution or foam, applied twice daily to the scalp. FDA-approved for AGA in men and women.
Low-dose oral minoxidil (LDOM), 0.25 to 5 mg/day, prescribed off-label by dermatologists. Often more convenient and as effective as topical for many people.

Timeline: a transient shed (the “dread shed”) is common in the first 4 to 8 weeks as follicles transition into a new cycle. Visible regrowth at 4 to 6 months. Maximum effect at 12 months. Stopping reverses gains over 6 to 12 months.

Side effects: scalp irritation and unwanted facial hair are most common with topical; hypertrichosis (extra body and facial hair, more common in women) and fluid retention are the main concerns with oral.