What's known about the rare, mysterious condition that causes people to allergically react to water

• Aquagenic urticaria is a rare condition where people have an allergic skin reaction to water.
• The reaction typically involves hives and bumps and can occur as often as several times a day.
• People with aquagenic urticaria can drink water, but they may react to bathing, crying, and rain.

Drinking enough water every day is vital for your body to function. So it seems impossible to survive with an allergy to water. However, in rare cases, skin contact with water can trigger an allergic reaction.

The scientific name for this rare condition is aquagenic urticaria. Hives — a type of itchy rash — develop rapidly after the skin comes into contact with water, including sweat or tears. The condition is only triggered by skin contact and not from drinking water, so those with aquagenic urticaria are not inherently at risk of dehydration.

Aquagenic urticaria is extremely rare and doctors don't have a full understanding of why it occurs. While there's no cure, there are strategies to manage the symptoms.

Can you be allergic to water?

As soon as people with aquagenic urticaria come into skin contact with water, they develop itchy hives, called urticaria. The hives are made up of raised bumps on the skin called wheals. Once the skin is dry, they generally fade within 30 to 60 minutes.

"Taking a shower, for example, or sweating, is then usually followed by wheals of the entire skin within a couple of minutes, whereas crying-induced signs and symptoms are limited to the areas where the tears touch the skin," says Marcus Maurer, MD, professor of Dermatology and Allergy at the Charité University Hospital in Berlin.

In more severe cases, the condition can also cause angioedema, a swelling of the tissues beneath the skin. This is a deeper swelling than hives and can be more painful. Both urticaria and angioedema tend to develop upon contact with water of any temperature.

Even though aquagenic urticaria resembles an allergy, it technically isn't — it's categorized more broadly as a disease. "The mechanisms that drive this disease are not allergic mechanisms," says Maurer.

Because of this, treatments that work for allergies, such as allergy shots — which work by injecting the patient with allergens to stimulate their immune system so they build up a tolerance — are not fully effective. While antihistamines can help by somewhat relieving the symptoms of hives, the best patients can do is try to avoid water contact.

Aquagenic urticaria is very stressful to manage

While the severity and frequency of a reaction varies, most patients react every day, several times per day, according to Maurer.

"Since water contact cannot be avoided, patients know that they will develop wheals and this results in anxiety, depression, and high-stress levels," Maurer says. For example, a 2019 Medical Science Monitor study found higher levels of depression and anxiety in patients with all types of chronic urticaria, including aquagenic urticaria.

Moreover, children with the condition have been reasonably scared of taking baths, and a mother with the disease had to be careful holding her son after she had a reaction to his tears.

Even eating and drinking can be stressful, because if water spills onto the skin or spicy food causes the patient to sweat, they will have an allergic reaction.

Aquagenic urticaria causes

Only about 50 cases of aquagenic urticaria have ever been reported, according to a 2016 paper published in the Journal of Asthma and Allergy. There are only four patients at Charité University Hospital in Berlin, where Maurer works, and that's one of the biggest urticaria centers in Europe.

Scientific research has uncovered little about how the disease works. Researchers know that when water touches the skin, it activates the allergy cells. These allergy cells are what cause hives and wheals. However, what researchers don't know is how water activates the allergy cells. This mechanism is understood for environmental allergens, like hay fever, but not for aquagenic urticaria.

According to Mauer, one hypothesis is that contact with water causes skin proteins to become auto-allergens, which then bind to receptors on skin allergy cells. However, research is limited because of the extremely low numbers of patients with aquagenic urticaria, and there's still little evidence to support any hypothesis.

And even though the course of aquagenic urticaria is unpredictable, doctors have noticed that it tends to fade later in life. "Most patients experience spontaneous remission after years or decades of having it," says Maurer.

Overall, Maurer says further resources are needed to fund more research and clinical trials for treatments of aquagenic urticaria. In the meantime, the global network of urticaria centers of reference and excellence features urticaria specialists and can help patients manage this rare condition.

Insider's takeaway

Aquagenic urticaria is a medical condition where your skin reacts to water — whether it's water from rain, tears, a shower, or something else. The severity of a reaction varies from person to person but it can happen as often as several times a day.

This can make living with aquagenic urticaria very difficult. Unfortunately, little is known about what causes this condition or how to treat it but some accounts suggest that symptoms fade with age.