A pair of identical twins have shown just how powerful Botox can be after only one of them underwent the injections for two decades, with strikingly different results.

The sisters took part in a long-running medical study where one twin began Botox treatments at age 25 while the other did not. Botox, the brand name for botulinum toxin, is a prescription drug often used cosmetically to smooth fine lines and wrinkles, but it also has medical applications in treating migraines, muscle stiffness, spasms, and excessive sweating.

The “Botox twin” received injections two to three times a year, targeting her forehead and the frown lines between her eyebrows. She also occasionally had treatments for crow’s feet, the fine lines that appear at the outer corners of the eyes.

Dr. William Binder, who carried out the injections, began documenting the sisters’ appearances in 2006 when they were 38 years old. Photographs from that year already showed clear differences: the Botox twin’s forehead was smoother and she had fewer visible lines around her eyes compared to her untreated sister, Derma Line reports.

But the gap became even more pronounced six years later. The twin who had never received Botox displayed deeper facial lines, a wider jawline, and puffier features. Researchers could not say whether those changes were directly linked to the absence of treatment, but the comparison strongly suggested that Botox played a role in slowing visible signs of aging.

Both women reported wearing sunscreen regularly and leading healthy lifestyles, ruling out excessive sun damage or poor habits as factors. However, environment may have contributed: the untreated sister lived in Munich, while her sibling resided in Los Angeles, a city with far higher sun exposure.

Dr. Binder concluded that long-term use of Botox can help prevent static wrinkles — the kind visible even when the face is at rest. He also noted that the treatment is “well tolerated” over time, with no adverse effects reported after 13 years of continuous use in the study.

The findings have since been echoed by physicians like Dr. Bita Farrell, a California-based doctor who recently experimented on herself to demonstrate the drug’s effects. With two decades of experience administering injectables, Farrell treated only the right side of her face, targeting muscles that naturally pull the mouth and jaw downward.

Two weeks later, she showed followers on social media how her expressions had shifted. The untreated side contracted strongly, pulling her jawline and mouth corners down. By contrast, the Botox-treated side looked smoother, more lifted, and less lined, giving her cheek a slightly higher, fuller appearance.

“Muscles of the face either pull up or pull down,” Farrell explained. “When the ones that drag the lower face down are relaxed with Botox, the cheek muscles dominate and lift everything up.”

According to experts, this lifting effect can soften marionette lines, reduce jowls, sharpen the jawline, and make the overall face appear more youthful.

The twin study and Farrell’s experiment both prove the same point: while Botox may sometimes spark debate, its long-term use can deliver visible and lasting results.