Topical minoxidil is minoxidil in a solution or foam applied to the scalp. It is sold over the counter as Rogaine and as store brands for hair regrowth.
Also known as: Rogaine, minoxidil foam, minoxidil solution.
Men's Rogaine comes as a 5% solution and a 5% foam. Women's Rogaine comes as a 2% solution and a 5% foam.
Topical minoxidil is an FDA-approved over-the-counter drug. The Drug Facts label use is to regrow hair on the top of the scalp (vertex). The directions are 1 mL of solution twice a day for the men's 5% and women's 2% solutions, half a capful of foam twice a day for men's 5% foam, and half a capful once a day for women's 5% foam.
The labels say results may take at least 4 months (at least 6 months for women's foam), and that new hair is lost if use stops. They say to ask a doctor first if you have heart disease, that the men's products are for men only, not for anyone under 18, and that minoxidil may be harmful during pregnancy or breastfeeding.
The Drug Facts labels give no half-life or time to peak, and we could not find a published human value for the topical form. In a study with radio-labeled minoxidil (Franz 1985), about 1.6 to 3.9% of the applied dose was absorbed, which the author estimated at 2.4 to 5.4 mg a day if applied to the whole scalp. The app's 22-hour half-life and 10.9-hour time to peak are modeling values we could not confirm, so neither is listed.