Water Allergy: Does It Exist and What Is Aquagenic Urticaria

After a shower, pool, or sea, the skin sometimes itches and breaks out in a rash, and the person decides they have a water allergy. Aquagenic urticaria is a real but extremely rare condition, and the picture of a reaction to water does not always match what is described with this diagnosis.

Can there be an allergy to water

A true allergy to water as a substance does not exist: "water allergy" is an everyday simplification. The human body is at least 60% water, so this condition cannot be a true allergy to water, despite the name. Water inside the body poses no danger in aquagenic urticaria: only the skin reacts, and only on external contact.

Aquagenic urticaria is sometimes called an allergy, but it does not belong to allergic diseases. It is an autoimmune condition: the immune system reacts to something inside the body, not to a foreign substance. Urticaria is very common; it is most often caused by medications and food, as well as infections and stress; it occurs more often in people with other allergies.

What is aquagenic urticaria

Aquagenic urticaria is an extremely rare form of physical urticaria: wheals appear from contact of the skin with water regardless of its temperature, purity, and salinity. Fewer than 100 cases have been described in the literature, and it is estimated to affect about 50 people worldwide. No remissions have been recorded, and the cause has not been determined.

Hypotheses differ: according to one, the immune system reacts to negligible amounts of an unknown substance dissolved in water; according to another, water interacts with a substance in the skin. By 2017, the prevailing version was an association with lactose intolerance and chromosome 2q21; among concomitant conditions, cholinergic urticaria and HIV infection are considered.

Symptoms: what a reaction to water looks like

The classic picture is itchy erythematous spots and wheals a few minutes after contact with water. The wheals are small, about 1–3 mm, red or flesh-colored, with a distinct border, most often on the neck, upper trunk, and arms. After the water source is removed, the rash usually disappears within 30–60 minutes.

• itching and burning after contact with water;
• small wheals and red spots with a distinct border;
• reaction to water of any temperature, purity, and salinity, as well as to sweat, tears, and saliva;
• disappearance of the rash within an hour after the skin dries.

Wheals do not always appear: the condition without a rash and redness is called aquagenic pruritus. Drinking water does not cause a reaction in some patients, while others feel pain and replace water with drinks containing less of it.

Pool, sea, and tap water

In aquagenic urticaria, water in any form causes a reaction — tap, sea, pool — regardless of purity and salinity.

Shower, hot water, and other types of urticaria

Hot water itself is not the cause: in aquagenic urticaria, water of any temperature causes a reaction. Sweat, tears, and saliva can also cause a reaction.

A separate task is to distinguish aquagenic urticaria from other types. The doctor may perform additional tests: an ice cube on the forearm for 1–3 minutes (cold), hands in hot water for 2–3 minutes (cholinergic), a pressure test (dermatographic).

How diagnosis is carried out and when to see a doctor

Diagnosis begins with the medical history: the doctor looks for signs of what could have caused the reaction. Then water is applied to the upper part of the body for 30 minutes — to the skin or through a moistened paper towel; for comparison, distilled water, tap water, and saline are used. After the water is removed, the skin is examined for another 10–15 minutes.

Urticaria usually resolves on its own within a few days. A doctor should be consulted if the rash does not improve within 2 days, spreads or returns, if there is a high fever and malaise, or if swelling appears under the skin. A separate reason is concern for a child with urticaria.

Urticaria by itself is not a reason to call an ambulance; call 103 or 112 if the lips, mouth, throat, or tongue suddenly swell, breathing becomes rapid or difficult, the throat tightens and swallowing is difficult, and the skin, tongue, or lips turn blue, gray, or pale.

This material is for reference only and does not replace a doctor's consultation: the cause of a rash is determined by a specialist during an appointment.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer