epocrates
AAD 2024: The lime in your margarita might give you a rash
Photoallergic or phototoxic reactions can be triggered by several substances – even your margarita. Dr. Brandon Adler, clinical assistant professor of dermatology at Keck School of Medicine of the University of Southern California in Los Angeles, presented on photocontact dermatitis at the recent American Academy of Dermatology Annual Meeting and explained that something as seemingly innocuous as lime juice on a hot day can trigger an uncomfortable condition known as “margarita rash.”
Margarita burns can occur when furocoumarin, a chemical compound found in plants, reacts with sunlight. Furocoumarin is found in limes and citrus fruits, along with celery, figs, fennel, and other plants. The condition, known medically as phytophotodermatitis, typically starts as a rash that forms within 24 hours. The degree of photosensitivity varies based on the amount of sun exposure and the concentration of the compound that affects the skin.
Although long-term effects of margarita rash are uncommon, hyperpigmentation or scarring is possible. An identical rash can be caused by skin contact and UV exposure with other plants, as well: various citrus fruits, figs, celery, parsnips, and carrots.
Contrary to previous understanding, people with dark skin are also at risk to photosensitivities, specifically polymorphous light eruption (PMLE) and chronic actinic dermatitis. PMLE causes tiny bumps or rashes to come and go with sun exposures, and chronic actinic dermatitis triggers year-round rashes that affect sun exposed parts of body.
Sources:
Adler, B, et al. Fun in the Sun: Photocontact Dermatitis and Related Conditions. Late-breaking research: session 1. Presented at: 2024 American Academy of Dermatology Meeting; March 8-12, 2024; San Diego, CA. https://am2024.aad.org/sessions/16895 [link requires log-in].
(2024, March 8). American Academy of Dermatology Association. Is your margarita giving you a rash? [News release]. https://www.aad.org/news/is-margarita-giving-rash