Dear Dr. K:  My cousin who lives in New Hampshire has developed an allergy to water. For the past two years she gets extremely itchy every time she showers, or whenever water touches her skin – but there is no rash. She has seen an allergist, but the various prescribed antihistamines haven’t helped. Do you have any suggestions?

Yes, I do.  First of all it sounds as if your cousin has idiopathic aquagenic pruritis. Usually, this condition just develops out of the blue, but it can be caused by some serious conditions such as Hodgkin’s disease, polycythemia vera, other blood disorders, and by some drugs. She needs to have her primary doctor exclude these possibilities.

If the water pruritis isn’t secondary to some other disease, then it is felt to be caused by inappropriate activation of the autonomic (automatic) nervous system. These nerves release neurotransmitters that seem to be the source of the itch. Since histamine is not generally released by these nerves, the use of antihistamines doesn’t usually stop the pruritis.

Some patients benefit by alkalinization of the tap water in their home. This possible benefit can be tested by taking a bath in water containing several boxes of baking soda.

Other patients benefit from the use of narrow-band UVB light phototherapy.

The treatment that has had the best success is the use of the beta-blocker drug propranolol. The beta system is a major component of the autonomic nervous system.

Finally, some people are helped by the alpha agonist (stimulator) clonidine. The alpha system is also part of the autonomic nervous system.