Meet the girl who is allergic to water

When she was 12, she broke out in hives after swimming in a hotel pool and needed Benadryl. Figuring it was a chlorine allergy, she avoided pools. Then she had the same reaction while swimming in a lake.

Allen has been diagnosed with aquagenic urticarial, a skin condition that involves flare-ups when coming in contact with water, including rain, sweat and tears. While not considered a true allergy, the condition causes a severe allergy-like reaction.

It's a very rare condition: Only 50 people have ever been diagnosed, according to ABC News.

"It's a real thing. We learn about it in medical school, though I have never seen a case in my practice," Dr. Barney Kenet of the Cornell Medical Center said.

To stay safe, Allen has become a vegetarian to reduce oil production in her skin, doesn't exercise much, and only takes two to three short cold showers per week. Humid climates must be avoided. When Allen went to Cambodia with a humanitarian group, the humidity triggered an allergic reaction.

Allen has spoken with Michaela Dutton, a British woman whom Fox News reported could only drink Diet Coke because of her condition.

There is no cure for aquagenic urticaria, which appears to be based on a genetic mutation, according to MD-Health.com. It affects women more than men, and is most likely to strike during puberty. It is a degenerative condition that will likely worsen with time.

To her credit, Allen is maintaining a positive outlook about her unusual ailment, saying at least she's not allergic to dogs and her condition gets her out of doing dishes.

Read ABC's full story.