Ketotifen (kee-toe-TYE-fen) is a type of asthma medication which, when taken every day and used along with other antiasthma medications, may reduce the frequency, severity, and duration of asthma symptoms or attacks in children. It may also lead to a reduction in daily requirements of other antiasthma medications. Ketotifen is not effective for the prevention or treatment of acute asthma attacks. Ketotifen works by inhibiting certain substances in the body that are known to cause inflammation and symptoms of asthma.