Can you be allergic to water? The answer is yes, although it is very rare. The medical term for it is called, aquagenic urticaria. It is a form of chronic hives that is characterized by the occurrence of itchy wheals after skin contact with water, such as bathing or swimming. The signs and symptoms of aquagenic urticaria commonly develop within 30 minutes after exposure to water and last 30 to 60 minutes. The bumps are usually 1 to 2 mm in size on the exposed areas of the skin. Other signs and symptoms can include swelling, headache, wheezing, difficulty breathing and some cases anaphylaxis.
The diagnosis is based on the persons history and testing. Recommendations to test is by placing a towel soaked with water on the patients trunk for up to 40 minutes. The result is positive when wheals are present at the test site 10 minutes after removal of the towel. The water temperature should be about 35-37 degrees Celsius.
Aquagenic urticaria should be differentiated from aquagenic pruritis (itch without skin changes to water) and other forms of cholinergic urticaria (cold and heat).
The rash from aquagenic urticaria occur in local areas regardless of water temperature. Aquagenic urticaria can be classified as familial (approximately 20%) and acquired (approximately 80%). In patients with aquagenic urticaria, skin contact with tap water was the most common trigger reported. Patients can also have symptoms related to water ingestion. Body fluids including sweat, saliva and tears have also been reported.
The typical treatment is second generation H1 antihistamines (such as Claritin, Zyrtec, or Allegra). Topical therapies most often do not work. Updosing is usually needed with antihistamines to achieve control. Using them up to 4 x a day may be necessary. Xolair (omalizumab) has been used successfully as well. Phototherapy has been used by some patients as well.
If you or someone you know thinks they may be allergic to water, they should see an allergist to determine the best treatment for them.