Michaela Dutton, 21, has aquagenic urticaria, which causes her to get hives when her skin comes in contact with water. While physical urticarias are not uncommon -- people can develop hives within minutes in response to ordinary stimuli including heat, cold and pressure -- sensitivity to water is far less common.
Dutton said she broke out in a red rash and white blisters after she took a bath about a week after her son was born three years ago. Although she ignored the reactions at first, her symptoms worsened and she went to see a doctor and a dermatologist who told her she had a water allergy.
"It's horrible," Dutton said. "I couldn't believe it at first," Dutton said.
"Water induced urticaria is very unusual -- there are not many cases ever reported," said Dr. Thomas Casale, chief of allergy and immunology at Creighton University and executive vice president of the American Academy of Allergy, Asthma & Immunology. "The mechanism has not really been defined."
It is certain, however, that people with aquagenic urticaria produce histamine from mast cells in the skin which causes redness, rashes and hives if they touch water. Dutton's sensitivity is such that she can only bathe for about 10 seconds each week and cannot drink water, juice, tea or coffee, opting for diet cola instead. She is also restricted from eating certain fruits and vegetables.
"It's not a problem with water in the body. It's when [water] is applied on top of the body," Casale said, citing additives as a possible cause for the allergic reaction seen on the skin.
Dutton, who lives in Walsall in the UK, also must be careful when holding her 3-year-old son. Her allergy was triggered after his birth and even his tears can cause hives.
"He doesn't really understand," Dutton said. "If he falls asleep I have to watch he doesn't dribble on me."
Physical urticarias tend to occur in individuals starting in their 20s and 30s but it is impossible to predict how long the condition will last.
"Some of these can be time limited but some can last for quite a few years," Casale said.
Most urticarias are treated with antihistamines but Casale said that because they are so rare, there have been no major breakthroughs in treatments.
About one in five people will develop hives at some point in their lives, but a much smaller number will get physical urticarias (urticaria is another word for hives) when they contact or experience some very ordinary things.
"If you put an ice cube on somebody that has cold urticaria, they're going to have a big welt right where the ice cube was," said Casale. And it's not just the cold. "It could be heat, could be sunlight. It could be vibration. It could be pressure."
In fact, some cases of heat-induced hives might be confused with exercise-induced anaphylaxis because exercise can raise body temperature.
Casale found the two could be distinguished for diagnosis by either heating the patient using a warming blanket or placing the patient's hand or leg in hot water. Only those with heat urticaria will develop hives.
An even smaller number of people with the condition may be diagnosed with aquagenic urticaria, meaning they are allergic to water.
"I actually saw a patient probably six or seven years ago. We put water on her and, boy, she just broke out in hives where the water hit her," said Casale, although he thought the reaction might have been provoked more so by the temperature of the water than the water itself.