Minoxidil is the active ingredient in products such as Regaine, that treat hair loss in men and women. It was first used in tablet form as a medicine to treat hypertension. Used in a lotion or foam, topical Minoxidil promotes hair growth in both men and women who have gradual hair loss (thinning hair) at the top of the head. It is not used to treat receding hairlines. It is a vasodilator, which means that it dilates blood vessels.
Minoxidil is not recommended for sudden, unexplained or patchy hair loss. It is also not suitable for women who have lost hair after having a baby.