Climate affects dose requirements for cosmetic Botox injections

Patients who live in “high sun” climates may need higher doses of Botox to achieve good results in the cosmetic treatment of facial lines and wrinkles, reports a study in its July issue Plastic and Reconstructive Surgery.

“In countries with more sun exposure, higher doses of Botox may be needed to achieve the same degree of forehead muscle paralysis, compared to less sunny countries,” comments lead author Kim L. Borsky, MBBS, MD, MRCS , of Stoke Mandeville. Hospital, Aylesbury, UK. “Our results suggest that plastic surgeons may need to adjust their Botox dosing protocols to account for the effects of climate on the results of this cosmetic treatment.”

Can sun exposure affect the response to cosmetic Botox?

The administration of “injectables” is the most common minimally invasive cosmetic procedure performed by plastic surgeons. According to ASPS statistics, the injection of neuromodulators such as botulism toxin type A — known by the trade name Botox — was administered more than 8.7 million times in 2022. Botox blocks nerve signals in the injected muscles, causing reversible muscle paralysis . This allows the lines and wrinkles of the overlying skin to soften and relax.

Plastic surgeons have seen variations in the improvement achieved with Botox injections. While several factors are known to influence response—including muscle mass, gender, age, and ethnicity—other, unrecognized factors may also play a role.

Could climate contribute to differences in response to cosmetic Botox injection? Dr. Borsky and his colleagues compared the results of Botox treatment in two groups of patients: a “high sun” group of 292 women in the Mediterranean island nation of Malta and a “low sun” group of 231 women treated in London in United Kingdom. Patients in Malta were treated during the summer months and patients in the UK during the winter months.

Botox treatments ‘may need to take climate into account’

Patients underwent Botox injections into the frontal muscles of the lower forehead. all treatments were performed by experienced plastic surgeons following a standardized technique. At follow-up visits, patients received “top-up” doses as needed to achieve “complete clinical paralysis.” The total dose of Botox required to achieve this effect was compared between the high sun and low sun groups.

The results showed a higher mean total Botox dose in the high helium group: 29.2 versus 27.3 units. Patients in Malta also received a higher mean supplemental dose: 2.24 versus 1.98 units. The differences in Botox dose remained significant after adjusting for age and other factors.

Why do patients in sunny climates need more Botox? Noting that the smooth muscles are the main muscle group involved in strabismus, Dr. Borsky and colleagues speculate that the difference may reflect greater development and functional activation of these muscles. Other possibilities include the effects of higher temperatures or the direct effects of sunlight on the response to Botox.

The researchers note that the small difference in their study is not likely to have a large impact on treatment costs, but may have implications for education and treatment.

“Rigid protocols regarding doses and distributions may lead to undertreatment if applied in sunnier climates,” Dr. Borsky and colleagues conclude. “Treatment protocols may need to take into account the climate in which treatments are given to achieve more predictable outcomes.”