Aquagenic urticaria

Before reading this, I would not have believed that it would be possible to be hypersensitive to water.

This is the world of Rachel Warwick, who is allergic to water... Any contact with water whatsoever – even her own sweat – leaves Rachel with a painful, swollen and intensely itchy rash which can last for several hours... Otherwise known as aquagenic urticaria, the condition is like being stung by a bush of particularly pernicious nettles, combined with the malaise of hay fever, every single day...

Technically, the condition isn’t actually an allergy at all, since it’s likely caused by an immune reaction to something within the body, rather than an over-reaction to something foreign, such as pollen or peanuts... In theory, anti-histamines should work every time. In practice, the drugs have decidedly mixed results... All they needed was a drug which could block IgE’s effects. And as luck would have it, there was already a drug on the market which could do just that.  Omalizumab was originally developed as a treatment for asthma... Since then scientists have discovered omalizumab is effective against even the most obscure forms of urticaria – from reactions to sunlight to changes in temperature, to friction.

Here is the relevant page from the Genetic and Rare Diseases Information Center at the NIH.