Cyproheptadine relieves red, irritated, itchy, watery eyes; sneezing; and runny nose caused by allergies, irritants in the air, and hay fever. It may also be used to relieve the itching of allergic skin conditions, and to treat hives, including hives caused by exposure to cold temperatures and by rubbing the skin. Cyproheptadine is also sometimes used to treat allergic reactions in people who have received blood products as part of medical treatment and to treat life-threatening allergic reactions after the symptoms have been brought under control with other medications. Cyproheptadine will help relieve symptoms but will not treat the cause of symptoms or speed recovery. Cyproheptadine is in a class of medications called antihistamines.