It is possible to be allergic to water. The condition is called aquagenic urticaria, and allergic reaction typically only occurs when water comes in contact with the skin. People who have aquagenic urticaria can still ingest water, according to Everyday Health.
Aquagenic urticaria is a rare condition that was first diagnosed in 1964. Symptoms of aquagenic urticaria include a red, itchy rash similar to hives and headaches. Any contact with water, even the patient's own sweat or tears, can bring about painful symptoms. Aquagenic urticaria is treated with antihistamines, anti-depression drugs, anti-cholenergic drugs or a combination of these, according to Everyday Health.