Antihistamines are administered to alleviate “allergy” symptoms, but too much use may magnify a more underlying sinus ailment.

Decongestants cause constriction or tightening of the blood vessels in the membranes of the nose and air passages, which forces much of the blood out of the membranes so that they shrink.

Many medications combine antihistamines and decongestants, which may reduce side effects of each.

Decongestants and/or antihistamines are the principal ingredients in cold remedies, but drying agents, aspirin, and cough suppressants may also be added.