Antihistamines [prescription such as Astepro, Clarinex, Optivar eyedrops; OTC such as Allegra, Benadryl, Claritin, Zyrtec]

Antihistamines block the action of histamines in the body. Histamines produce allergic reactions (such as itching, sneezing, rashes and hives) to stimuli (dust, plants, pet dander, food, chemicals). Antihistamines act on symptoms, blocking the body’s histamine receptors. The most common side effect of antihistamines is drowsiness. Non-drowsiness formulas of many of these drugs are available.