Most people don’t like to go outside when it’s pouring. You become wet and cold, which is not that pleasant. But actually, these feelings of discomfort are nothing compared to what people suffering aquagenic urticaria experience when they are caught in the rain.
This rarely diagnosed form of hives is characterized by a painful skin reaction resulting from contact with water of any kind, which could be rain, but also the patient´s own (or someone else’s) sweat and tears.
Soon after being exposed to water their skin starts to itch and burn, and may develop pale red, raised bumps. This can also occur in the throat after drinking water, causing swelling and shortness of breath. These symptoms usually persist for between 10 minutes to an hour.
Aquagenic urticaria is sometimes described as an allergy, but actually it does not seem to be caused by histamine release like the other types of hives, which triggers an inflammatory response. Instead, scientists believe that this condition is caused by exquisite skin sensitivity to additives in the water such as chlorine.
Unfortunately there is no known treatment, so staying cool, carrying around an umbrella and avoiding emotional situations seems like the best thing to do.
Hoon Park, Hee Su Kim, Dong Soo Yoo, Jin Woo Kim, Chul Woo Kim, Sang Seok Kim, Jong Ik Hwang, Jun Young Lee & Yoon Jeong Choi (2011). Aquagenic Urticaria: A Report of Two Cases Annals of Dermatology DOI: 10.5021/ad.2011.23.S3.S371