Botox was developed for eye muscle disorders — the wrinkle treatment was a side effect

In 1973, ophthalmologist Alan B. Scott injected botulinum toxin into monkey extraocular muscles and achieved targeted, long-lasting paralysis without side effects. He was searching for a treatment for strabismus (crossed eyes) and blepharospasm (uncontrollable blinking). The toxin was a purified form of the most lethal substance known — botulinum toxin type A — but Scott believed it could be used therapeutically in tiny, controlled doses.

Scott named his drug Oculinum ('eye aligner') and founded Oculinum Inc. to manufacture it. In 1977 he injected the first strabismus patients. By 1985 a clinical protocol was established. The company faced a crisis in 1986 when its product liability insurance was canceled, and for four months American blepharospasm patients had to travel to Canadian clinics. In December 1989, the FDA approved Oculinum for strabismus and blepharospasm under the Orphan Drug Act. Allergan acquired the drug and rebranded it as Botox.

The market for eye muscle disorders was tiny. Strabismus affects about 4% of the population, but only a fraction sought the injection treatment. Blepharospasm is a rare condition affecting roughly 50,000 people in the US. Botox was a niche medical product with limited commercial potential. Allergan saw it as a low-priority asset.

In 1992, dermatologist Jean Carruthers published a landmark study showing that botulinum toxin eliminated glabellar frown lines — the '11s' between the eyebrows. She had noticed the effect in her blepharospasm patients: their chronic frowning disappeared along with the spasms. The cosmetic application was entirely accidental. Allergan initially resisted the cosmetic market, fearing it would trivialize a medical product. Botox Cosmetic was finally FDA approved in 2002 and became the fastest-growing pharmaceutical product. By 2024, the global cosmetic Botox market exceeded $6 billion annually.