The hair-loss drug first developed as an oral antihypertensive was minoxidil. It began as a blood-vessel-widening medication, then became famous after hair growth was observed in people taking it.
The Upjohn Company developed related compounds in the late 1950s while investigating treatments for ulcers. One compound, minoxidil, proved to be a powerful vasodilator. The U.S. Food and Drug Administration approved oral minoxidil under the brand name Loniten for severe hypertension in 1979.
Hair growth became an important side effect and eventually a new indication. Topical minoxidil was approved for male pattern baldness in the United States in 1988 under the brand name Rogaine, with a women’s formulation following later. It is now available as a liquid or foam, while low-dose oral use for hair loss is generally an off-label practice in many settings.
Finasteride is the main distractor: it is also used for hair loss, but it works by reducing conversion of testosterone to dihydrotestosterone. Minoxidil instead promotes follicle activity through a mechanism involving potassium channels and its active sulfate metabolite; stopping it usually causes regrown hair to be lost over time.