Minoxidil hair loss drug molecule, computer model. Atoms are represented as spheres and are colour- coded; carbon (green), hydrogen (white), nitrogen (blue) and oxygen (red). Minoxidil (which is marketed as regaine) is a vasodilator and was originally used to treat high blood pressure. However, it was discovered that one of its side effects was to cause hair regrowth. Minoxidal was put in a topical solution and is now used to treat baldness. How the drug stimulates hair growth is not known.