Minoxidil wasn't supposed to grow hair. In the 1960s, chemists at the Upjohn Company in Kalamazoo, Michigan were trying to develop a treatment for stomach ulcers. What they created instead was a potent vasodilator that lowered blood pressure — and gave patients an embarrassing side effect that would eventually become the most popular hair loss treatment on the planet.
The molecule that would become minoxidil was first synthesized in 1963 as part of Upjohn's ulcer research program. When it showed no promise for ulcers but demonstrated powerful vasodilatory properties, the company pivoted to developing it as an antihypertensive medication. Oral minoxidil was approved by the FDA in 1979 under the brand name Loniten for the treatment of severe, refractory hypertension — high blood pressure that didn't respond to other medications.
Almost immediately, doctors noticed something unexpected: patients on Loniten were growing hair — sometimes a lot of it. Not just on their heads, but on their arms, backs, faces, and ears. The medical term for this side effect is hypertrichosis, and it affected roughly 80% of patients taking the oral medication. For many, it was an unwelcome nuisance. But for balding men, it was a revelation.
Throughout the early 1980s, dermatologists began experimenting with applying minoxidil directly to the scalp as a topical solution, reasoning that local delivery might provide the hair growth benefits without the cardiovascular effects of the oral drug. These early studies were promising enough to attract Upjohn's attention, and the company launched formal clinical trials of a 2% topical minoxidil solution.
In 1988, the FDA approved topical minoxidil 2% (branded as Rogaine) for the treatment of androgenetic alopecia in men. It was the first FDA-approved medication for hair loss — and it created an entirely new category in consumer health. The 5% extra-strength formulation followed in 1997, and minoxidil transitioned from prescription to over-the-counter status in the US, making it widely accessible without a doctor's visit.
Despite decades of research, the exact mechanism by which minoxidil stimulates hair growth isn't fully understood — which is remarkable for such a widely used medication. What we know is that it works through multiple pathways:
Potassium channel opening: Minoxidil is a potassium channel opener. It activates ATP-sensitive potassium channels in vascular smooth muscle cells, causing them to relax. This widens blood vessels around hair follicles, increasing the delivery of oxygen, nutrients, and growth factors to the follicular papilla — the structure at the base of the follicle that drives hair production.
The prodrug conversion: Minoxidil itself is inactive. Your body must convert it into minoxidil sulfate using an enzyme called sulfotransferase. This active metabolite is what actually stimulates follicular activity. The variable expression of this enzyme between individuals is a major reason why some people respond well to minoxidil and others don't.
Growth phase extension: Minoxidil prolongs the anagen (active growth) phase of the hair cycle and shortens the telogen (resting) phase. This means hairs spend more time growing and less time dormant, resulting in longer, thicker hairs and increased overall coverage.
Follicle enlargement: In addition to growth phase effects, minoxidil appears to increase the physical size of miniaturized follicles. This reversal of miniaturization — even partial — transforms thin, invisible vellus hairs into cosmetically significant terminal hairs.
In an ironic twist, the hair loss world may be circling back to oral minoxidil. In 2026, Veradermics' VDPHL01 — the first extended-release oral minoxidil formulation designed specifically for hair loss — achieved positive Phase 3 results. Unlike the original Loniten (which was designed for blood pressure and caused widespread body hair growth), VDPHL01 is engineered for sustained, low-dose delivery that targets hair growth while minimizing cardiovascular effects.
If VDPHL01 reaches the market, it would be the first FDA-approved oral treatment for hair loss — bringing minoxidil's 60-year journey full circle from accidental oral side effect to intentional oral therapy.
Minoxidil's journey from failed ulcer drug to failed blood pressure drug to the world's most popular hair loss treatment is one of medicine's most serendipitous stories. The science behind it — potassium channel opening, sulfotransferase conversion, growth phase extension — is increasingly well-understood, and the next generation of oral formulations may bring its efficacy to new heights while keeping safety at the forefront.
FDA-approved brand-name hair loss medications via telehealth