Ketotifen is a second-generation H1-antihistamine and mast cell stabilizer. It is most commonly sold in as a salt of fumaric Acid, ketotifen fumarate, and is available in two forms. In its ophthalmic form, it is used to treat allergic conjunctivitis,or the itchy red eyes caused by allergies. In its oral form, it is used to prevent asthma attacks. Side effects include drowsiness, weight gain, dry mouth, irritability, and increased nosebleeds.

The drug is marketed as ophthalmic solutions under the brand names Zaditor/Zaditen (Novartis), Alaway (Bausch and Lomb), Zyrtec Itchy-Eye Drops, and Claritin Eye. A generic version of Novartis' Zaditor, ketotifen fumarate ophthalmic solution, 0.025%, is available from Perrigo and distributed as store brands. In South Korea 'Uniten-F Eye Drops (ketotifen fumarate 0.345mg/ml, 0.25mg as ketotifen)' which is a generic version of Zaditor and is selling as Over-The-Counter is also available from Unimed Pharmaceutical INC.[

ketotifen fumarate