Alexandra Allen had her first allergic reaction to water when she was about 12 years old. She was on vacation with her family, and, after swimming in a hotel pool, woke up to burning itchiness and her skin broken out in hives, The American Register reported.

The 17-year-old from Mapleton, Utah, is one of about 50 known people in the world to be diagnosed with aquagenic urticaria, a condition that causes an allergic reaction when rain, snow, sweat or tears touches the skin. Urticaria is the medical term for hives.

Allen was officially diagnosed with the condition at age 15, after conducting personal research then consulting her dermatologist, according to The American Register. Since her diagnosis, the teenager has become a vegetarian to reduce oils in her skin and has steered clear of swimming pools. She also takes only two to three brief showers per week and avoids sweating when she can.

Although little is known about aquagenic urticaria, it is thought to be most common among women, and it historically has appeared in those people affected following puberty or several years later. Allen spoke in 2014 with a British woman who was also diagnosed with the degenerative condition and said she has had to switch to sipping only Diet Coke, as drinking water causes her skin to break out.

According to a 2011 study published in the journal Annals of Dermatology, the first three cases of aquagenic urticarial were reported in 1964. Since then, fewer than 100 cases have been discussed in scientific literature. In that study, fexofenadine, which also takes form as the common allergy medicine Allegra, successfully treated a 19-year-old man diagnosed with the condition. Ketotifen syrup bid, a medication to treat asthma attacks, improved symptoms in a 4-year-old boy with aquagenic urticaria. The condition is sometimes associated with other common triggers for hives, like sunlight, pressure or cold temperatures.

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