Minoxidil because of its ability to cause blood vessels to dilate. However, some doctors who had been prescribing the medication to treat high blood pressure noticed a fascinating side effect in certain patients: their eyebrows began to thicken, and some of them began to grow hair on their bald spots.

Dermatologists quickly took note of this interesting phenomenon and began to experiment with liquid solutions containing minoxidil. They demonstrated that a topical solution applied to bald spots on the forehead and the back of the head slowed hair loss and stimulated the regrowth of hair.

Minoxidil had previously been approved by the FDA as a vasodilator to be used in treating high blood pressure. After a number of pharmaceutical studies, it gained approval as a stimulant with the capability to grow hair. Upjohn Corporation obtained a patent for the formula; the company marketed their minoxidil solution as Rogaine in the U.S. and Canada, and as Regaine in European countries.

In 1997, a foam-based version of minoxidil was formulated as a convenient alternative to the liquid solution. Minoxidil is an effective hair loss treatment with few adverse side effects, none of them severe. Because of this, it remains the best-known and most popular hair growth stimulant on the market today.