Minoxidil solution and foam are used to help hair growth in the treatment of male pattern baldness.

Minoxidil (2,4-diamino-6-piperidinopyrimidine 3-oxide), sold under the brand name Rogaine among others, is a medication used for the treatment of high blood pressure and pattern hair loss in males and females. It is an antihypertensive vasodilator. It is available as a generic medication by prescription in oral tablet form and over the counter as a topical liquid or foam.Minoxidil, when used for hypertensive is generally reserved for use in severe hypertension patients who can't respond to atleast two agents and a diuretic. Minoxidil is also generally administered with a loop diuretic to prevent the sodium and potassium retention. It may also cause a reflex tachycardia and thus is prescribed with a beta-blocker.

Minoxidil, applied topically, is widely used for the treatment of hair loss. It is effective in helping promote hair growth in people with androgenic alopecia regardless of sex.Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth.

The mechanism by which minoxidil promotes hair growth is not fully understood. Minoxidil is an adenosine 5'-triphosphate-sensitive potassium channel opener, causing hyperpolarization of cell membranes. Theoretically, by widening blood vessels and opening potassium channels, it allows more oxygen, blood, and nutrients to the follicles. Moreover, minoxidil contains a nitric oxide moiety and may act as a nitric oxide agonist. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase. Minoxidil is a prodrug that is converted by sulfation via the sulfotransferase enzyme SULT1A1 to its active form, minoxidil sulfate. The effect of minoxidil is mediated by adenosine, which triggers intracellular signal transduction via both adenosine A1 receptors and two sub-types of adenosine A2 receptors (A2A and A2B receptors).

Minoxidil acts as an activator of the Kir6/SUR2 channel upon selective binding to SUR2. The expression of SUR2B in dermal papilla cells might play a role in the production of adenosine. Minoxidil induces cell growth factors such as VEGF, HGF, IGF-1 and potentiates HGF and IGF-1 actions by the activation of uncoupled sulfonylurea receptor on the plasma membrane of dermal papilla cells.