Postnasal drip generally refers to postnasal drip syndrome. Bad breath caused by postnasal drip syndrome requires active treatment of postnasal drip syndrome. Diseases that cause this syndrome include: chronic rhinitis, chronic sinusitis, allergic rhinitis, etc. Medication is often taken according to the cause. Postnasal drip syndrome refers to a series of uncomfortable symptoms caused by the chronic inflammation of the nasal cavity and sinuses, in which the purulent secretions produced by the inflamed parts flow backward through the nasal cavity and through the nostrils into the nasopharynx, oropharynx and hypopharynx. For example, for chronic sinusitis caused by coccobacillus infection, penicillin, cephalosporins as the first choice of drugs; for chronic rhinitis caused by the use of budesonide nasal spray, mometasone furoate nasal spray treatment; for allergic rhinitis can be used antihistamines, such as: levocabastine hydrochloride, cetirizine, loratadine, and so on. When postnasal drip syndrome occurs, after the doctor clarifies the diagnosis and cause of the disease, follow the doctor’s instructions to standardize the use of medication and treatment, and do not judge and deal with it on your own.