A decades-old study comparing identical twin sisters is going viral again after showing how their faces aged when one received regular Botox for nearly 20 years while the other largely went without.
The research, led by Dr. William J. Binder of the UCLA School of Medicine, has resurfaced online as people debate whether long-term Botox actually slows visible skin aging or simply comes with an expensive price tag.
Highlights
- An identical twin study that lasted nearly two decades has resurfaced online, reigniting debate over one of the world's most popular cosmetic treatments.
- While one sister received regular Botox injections for years, researchers kept nearly every other major lifestyle factor remarkably similar.
- Experts say the findings continue to influence how cosmetic doctors think about wrinkle prevention today.
The study has also highlighted one of cosmetic medicine's biggest questions: Can repeated Botox injections prevent wrinkles from becoming permanently etched into the skin?
One twin received regular Botox for almost 20 years while the other barely used it, giving doctors an opportunity to compare how their faces aged
Dr. Binder, a facial plastic surgeon affiliated with the UCLA School of Medicine, first began treating one of the identical twin sisters with Botox in 1992.
In the comparison study and several of his published medical papers, Dr. Binder also noted that he was a stockholder and formal consultant for Allergan Inc., the manufacturer of Botox.
Over the next 13 years, the unidentified twin received injections two to three times annually, while her sister underwent the treatment only twice during that period.
The results were published in 2006 in the Archives of Facial Plastic Surgery, with researchers later continuing to monitor the sisters for another six years.
Their findings were updated in a 2015 follow-up, bringing the total observation period to nearly two decades.
The study was designed to answer a question that was largely unexplored at the time: Could Botox actually help prevent permanent wrinkles from forming?
Because the sisters shared virtually identical genetics and remarkably similar lifestyles, researchers were able to isolate Botox as the primary difference between them.
As Dr. Binder noted in the paper, "Both twins use 45 to 50 SPF sunblock on a daily basis, and both lead active outdoor lifestyles. Neither twin smokes, both adhere to a relatively healthy diet, and both work in an indoor office setting."
He added, "Neither twin has had any laser, light, or skin-tightening procedures, and both use glycolic-based topical skincare products on a daily basis... consistent long-term treatment with onabotulinumtoxinA seems to be the only major difference in the lives of these twins."
However, experts at Aesthetic Dermatology in Pennsylvania note that the treatment cannot prevent wrinkles caused by sun damage or address every aspect of facial aging.
Despite sharing nearly identical lifestyles, the twin who received regular Botox developed noticeably fewer permanent facial lines
That made the sisters an unusually strong real-world comparison, allowing researchers to observe how one major variable, consistent Botox use, appeared to influence facial aging over time.
When researchers compared photographs of the sisters after 13 years, the differences were most apparent in the areas that had been consistently treated.
The twin who received regular Botox showed little to no permanent forehead lines at rest, while her sister had developed clearly visible static wrinkles in those same areas.
However, experts caution that Botox is only one aspect of skin aging.
As surgeons at the Aesthetic Dermatology note, "Botox is one tool, not the whole toolbox," with factors such as genetics, sun protection, skincare, and overall health continuing to influence how skin changes over time.
The treated twin also had noticeably softer crow's feet around her eyes.
Interestingly, the differences were limited to the regions where Botox had actually been injected.
Areas that were never treated, such as the nasolabial folds around the mouth, appeared to age at roughly the same rate in both sisters.
Researchers said this suggested Botox wasn't slowing the overall aging process, but rather helping protect the skin from repeatedly folding in specific areas.
While many people believe Botox works only while it's actively in the muscles, the researchers observed that the treated twin's smoother appearance persisted even after the injections had worn off.
Dr. Binder concluded that long-term treatment appeared to help prevent wrinkle formation, writing that Botox may work "not only by inhibiting the patient's ability to contract the target muscle but also perhaps through behavioral modification."
While the research focused on expression lines caused by repeated muscle movement, dermatologists argue that Botox specifically targets dynamic wrinkles and does not address other age-related changes such as volume loss or sagging skin.
Dr. William J. Binder believes years of regular Botox may even "teach" facial muscles to stop creating wrinkle-forming expressions
Researchers also noted that the twin who received regular treatments appeared to have smoother overall skin texture in the treated regions.
This suggested that minimizing years of repeated muscle movement may have allowed the overlying skin to remain in better condition over time.
One of the study's more intriguing conclusions was that repeated treatment might gradually change the way people naturally use facial muscles.
According to Dr. Binder, patients who receive Botox consistently over many years may eventually stop making the exaggerated facial movements that repeatedly crease the skin, even after the effects of the injections fade.
He wrote, "With long-term treatment, the patient may become used to having little, if any, need or ability to contract the target muscle and may eventually 'learn' to avoid even trying to contract it."
Researchers suggested this "behavioral modification" could partly explain why the regularly treated twin continued to show fewer permanent forehead lines than her sister, despite both women aging under nearly identical conditions.
The study also found that maintaining these results did not require increasingly larger doses over time.
Instead, the treated twin remained on a relatively conservative treatment schedule throughout the observation period, receiving injections just two to three times a year.
However, dermatologists caution that no single study can determine whether Botox is the right choice for everyone.
As Aesthetic Dermatology notes, "The best step is always a conversation with a board-certified dermatologist who can look at your skin, your goals, and give you actual personalized advice instead of a generic sales pitch or a generic dismissal."
The comparison also sparked debate over aging naturally, Botox safety, and whether the differences were even noticeable
While many viewers found the decades-long comparison fascinating, others weren’t convinced the results justified years of regular Botox treatment.
"Identical twin studies are always fascinating, and I'm going to be honest, 13 years of Botox toxin injections versus untreated natural aging, I saw extremely little difference between the two ladies," one netizen wrote. "They're both beautiful."
Another commented, "Almost no result after 13 years of Botox treatments? I don't understand why people worry about wrinkles. It is ridiculous."
A third user fumed, "The only problem I have with any of it is our absolute panic over showing our age. Making sure your skin is healthy is one thing - fearing the inevitable aging process is entirely another, imo."
"I may be in the minority here, but I embrace my age, my gray hair, my wrinkles and scars - all the rusty parts of my body. It tells my story, my history, and it doesn't pretend that it has all been pretty."
"Crow's feet? Oh, you mean laugh lines. They are definitely not a turn off," one user wrote, while another agreed, saying, "I think it's charming."
Many even questioned the safety of long-term Botox use, with one user writing, "The risks of Botox do not outweigh the benefits."
At the same time, a handful of people opened up about using Botox for medical conditions rather than cosmetic purposes.
One comment read, "I get Botox for my migraines, and it works amazingly, as I can LIVE now!"
"I have had Botox against migraines for years now, too, and it works so well... Nobody has ever noticed anything off about my face."
“As much as the Botox one has less wrinkles, she doesn’t look much younger. They still look a similar age,” one person wrote
