Rogaine (also branded as Regaine outside the US) is the brand name for Minoxidil, when used as a topical drug to treat male pattern baldness. The solution is applied to the scalp daily to stimulate hair growth and help prevent hair loss. It is available over-the-counter (OTC) in the U.S. in a 2% Minoxidil solution and also 5% Minoxidil solution (Rogaine Extra Strength).