Histamine is a chemical produced by an allergy-producing white blood cells called mast cells. Histamine causes allergic reactions in the skin – HIVES (urticaria) or SWELLING (angioedema) and nose and eyes – SNEEZING, RUNNY NOSE, ITCHY EYES (hay fever).
Antihistamines block the effect of histamine. They have been used to treat allergies since the 1940s.
Because of side-effects these antihistamines should be avoided. Piriton is still used in young children as it is one of the only antihistamines licenced in this age group.
Second generation antihistamines are now recommended to treat allergies symptoms. They are similar in their effectiveness and one is recommended dependent on market price.