Keratan is mainly used to relieve symptoms associated with allergic rhinitis, such as recurrent sneezing, runny nose, itchy nose, nasal congestion, itchy eyes, itchy palate, and burning sensation. Symptoms and signs related to the nose and eyes can be relieved rapidly after oral administration of the drug. It is also indicated for the treatment of related skin diseases, such as chronic urticaria, pruritus, and allergic skin symptoms and signs. The drug is relatively sensitive, and there are certain adverse reactions to the drug, the most common of which may be weakness, headache, drowsiness, dry mouth, and gastrointestinal discomfort, allergic reactions are relatively rare, as well as autonomic nervous system, such as lacrimation, flushing, excessive sweating, which may also occur occasionally. For the central system, gastrointestinal system, muscular and skeletal system, and reproductive system, the side effects are relatively small and rarely occur.