Science Questions

The common reaction to allergy is a rash. Why is this and what good does it do? Nigel in Northampton

A common to reaction to an allergy is more to have you nose run or to wheeze, but the same sort of process can happen in your skin. That histamine is making the blood vessels leak out their fluid rather than the red cells in them and that makes the skin swell up and go red. The mast cells that do this histamine release are also found in your skin. They're just under the skin. I think it's very important to realise that quite a lot of people get hive or urticaria most days of the year. In fact, they have chronic urticaria. This is not an allergy but many GPs will look at them and say it must be an allergy because they've got a rash. It never is in that situation and it's worthwhile seeing an immunologist or a doctor and getting that sorted out.

July 2006