Patients sometimes tell me their wrinkle-relaxing treatment seems to wear off sooner during a vacation or after spending more time outdoors. It is an interesting observation, but it does not establish that sunshine or warm weather is breaking down their treatment.
A study published in Plastic and Reconstructive Surgery in 2024 explored a related question: whether patients treated in different climates required different doses of botulinum toxin.
What did the researchers examine?
The study reviewed women receiving treatment for glabellar lines—the frown lines between the eyebrows—from one provider practicing in two locations.
One location was in the United Kingdom, described as having lower sun exposure. The other was in Malta, with higher sun exposure.
Researchers compared the doses used to achieve the intended treatment response and considered potential differences between the patient groups.
What did the study find?
Patients in the higher-sun-exposure location required a higher average dose. The difference was relatively small, although the researchers considered it potentially relevant to treatment planning.
This finding suggests that climate-associated factors may deserve further investigation. It does not establish a universal dosing adjustment for people living in sunny places.
What does it not tell us?
The study examined dose requirements. That is different from measuring how quickly an established treatment wears off.
It does not prove that taking a beach vacation, exercising outdoors, or living in a warmer climate causes Botox to stop working sooner. It also does not establish that a particular patient needs more treatment because they spend time in the sun.
Because this was an observational comparison, differences between the locations cannot automatically be attributed to sunlight alone.
What if your results seem shorter than expected?
The first step is reviewing what actually changed. Did muscle movement return sooner, or did a line remain visible even while movement was reduced? Was the same product, dose, and area treated?
Facial anatomy, muscle activity, treatment goals, and previous response can all influence the assessment. A persistent line at rest is not necessarily evidence that the medication has worn off.
Standardized photographs and an appropriate follow-up can be more useful than guessing at the cause.
Should you change your treatment around travel?
Tell your provider about upcoming travel and important events so there is time to assess the response and address concerns.
However, this study alone is not a reason to increase your dose before a sunny vacation. Treatment should remain individualized.
Sun protection is still important for limiting UV damage and premature skin aging, regardless of whether you receive wrinkle-relaxing injections.
At Modern Aesthetics in San Jose, I consider your history, muscle activity, goals, and response when planning treatment. If your results are behaving differently, we can review the details together.
Reference: Borsky KL, Rodrigues JN, Rodrigues R. “The Effect of Climate on the Dose Requirements of Botulinum Toxin A in Cosmetic Interventions.” Plastic and Reconstructive Surgery. 2024;154(1):57e–62e. DOI: 10.1097/PRS.0000000000010913.
Updated October 23, 2026.