Antihistamine medicines block the action of the chemical histamine during an allergic reaction to an irritant (allergen). Allergic symptoms, such as sneezing and itching, are not as bad when an antihistamine is taken.

It's important to check with a doctor before giving antihistamines to a child.

Some antihistamines can be bought over-the-counter, and some are prescribed. They can be taken by mouth (oral) or applied directly to the skin (topical). Pills and capsules contain a specific dose of medicine. The dose in a cream or ointment depends on how much is applied at one time and is harder to control. Too much antihistamine absorbed through the skin can be toxic, especially to children. The use of cream or ointment antihistamines is not reliable and not recommended.