Aquagenic urticaria, also known as 'water allergy' and 'water urticaria', is a rarely diagnosed form of physical urticaria. It is sometimes described as an allergy, although it is not a true histamine-releasing allergic reaction like other forms of urticaria. The defining symptom is a painful skin reaction resulting from contact with water. This may also be the effect of different temperatures of water, such as cold or hot, and can flare with chemicals such as fluorine and chlorine.
Aquagenic urticaria causes the skin to itch extremely and occasionally burn after being exposed to water of any kind. The skin may develop hives or spots. Showers may result in severely dry eyes and soreness. Higher water temperature tend to expedite the formation of hives. Shortness of breath or swelling in the throat can occur when drinking water. The pain usually persists for between 10–120 minutes.
Contact with any form of water can cause symptoms to appear. One's own or someone else’s sweat can cause a reaction, so most affected people try to stay cool in summer to avoid sweating as much as possible. Tears on one's face from crying can also cause pain. Most people with aquagenic urticaria try to stay out of the rain and carry umbrellas as a precautionary measure. Cleansing the body often induces such an intense reaction that affected people may take very short showers to lessen the severity of the pain. Aquagenic urticaria, although rare, is more common in young teens (14-16 years old) and is almost unheard of in adults.