Anti-allergy Eye Drops are medications used to prevent and treat itching of the eyes caused by allergies or seasonal conjunctivitis. These are eye drops or gels that have been specifically made to be administered into or around the eye that contain antihistamines and/or decongestants. Antihistamines block histamine release from histamine-1 receptors and are used to treat the symptoms of an allergy such as swelling, itch, inflammation, and watery eyes. Decongestants relieve congestion by narrowing blood vessels.