Considering the human body is about 60 percent water it seems implausible — if not impossible — to be allergic to water, but about 40 people worldwide have been diagnosed with the condition. Known as aquagenic urticaria, it causes the skin to break out in painful hives and welts when it comes in contact with water, and in severe cases, a person's throat can swell when they drink water. Michaela Dutton (pictured) a British woman who developed a water allergy after the birth of her son, drinks Diet Coke to survive — her body tolerates it even though it contains carbonated water. How do people like Dutton bathe? Quickly and carefully because even brief contact with water can cause a painful itchy rash that lasts for hours. Doctors aren't sure what causes water allergy, but some have hypothesized that elevated histamine levels play a role.