Water allergy

It's also known as "aquagenic urticaria" and it's extremely rare. Sufferers appear to be allergic to water. It usually occurs late in life and often as a consequence of a hormonal imbalance brought about by giving birth.

A case emerged in the UK in April this year, leaving a 21-year-old mother unable to drink water or get caught in the rain because her skin develops a painful burning rash. She can shower for a maximum of 10 seconds per week and can drink only Diet Coke. It is not strictly an allergy but a hypersensitivity to the ions found in non-distilled water.