Aquagenic urticaria is an unusual dermatological condition that is characterized by the appearance of a rash after exposure to water. The rash can break out within minutes of water exposure, and may last for up to two hours. It is common for the rash to be itchy and painful, which can cause extreme discomfort for the patient. There is no cure for aquagenic urticaria, although sometimes medications can be prescribed to manage it, and the condition may be congenital or acquired. Some patients experience an onset after medical treatment for another condition, for example, and find that their sensitivity to water wanes over time.
This condition is sometimes described as a “water allergy,” but that is not quite accurate. Histamine responses do not always appear to be involved in aquagenic urticaria, which means that an allergic reaction may not actually be occurring in all cases. Research seems to suggest that people who have this condition are simply extremely sensitive to substances found in water which is not distilled, including ions which are naturally present along with additives such as chlorine.
When someone with aquagenic urticaria is exposed to water, red hives appear on the skin. A blotchy rash can appear anywhere that water came into contact with the body, and may itch or burn. Antihistamine medications do not reduce the rash, although some topical medications can ease the itching and swelling. The rash will resolve on its own as long as the patient stays dry.
A doctor can diagnose aquagenic urticaria by exposing a patient to regular and distilled water and noting the responses. The distilled water should not elicit a reaction. Once diagnosed, the patient needs to focus on management of the condition. Things like showers and baths usually must be kept brief, while the patient usually cannot engage in activities like swimming. Patients can also be sensitized to sweat, and may be advised to refrain from sweaty activities and to stay cool on hot days so that they do not sweat.
As discussed above, some patients with aquagenic urticaria find that their sensitivity to water decreases over time, which may allow them to engage in more activities. Because this condition is rare, it is important that patients make care providers aware of the situation, and for young children, advising teachers and child care providers about aquagenic urticaria is also recommended. Patients may also want to consider carrying a medical alert card with information about their condition so that in the event that they are in a medical emergency, care providers will be alerted to their water sensitivity.