Babies with frequent runny nose may have the following reasons: 1. Allergic rhinitis or sinusitis: If allergic rhinitis or sinusitis occurs, in addition to runny nose, babies may also have symptoms such as nasal blockage, open mouth breathing, nasal itching, sneezing and scratching the nose with hands. If these symptoms occur, a nasal examination at the ENT department is needed to determine if allergic rhinitis or sinusitis is present. If present, treatment with physiological seawater rinses and nasal sprays may be required. If the condition is serious, oral medication may also be required for treatment; 2. Nasal foreign body: usually manifests as nasal discharge from one nostril, or even nasal discharge with blood and odor. As babies explore the world, they like to place round objects into the nasal cavity, mouth or external ear canal. If a foreign object enters the nasal cavity, it may lead to recurrent runny nose with a small amount of blood and sometimes a foul smell. In this case, it is also necessary to go to the hospital for examination and if a foreign body is found, it must be removed in time. Parents should also remind their babies to avoid contact with small round objects to prevent nasal foreign bodies. 3. Cerebrospinal fluid rhinorrhea: Some children have a history of head trauma, and the runny nose is mostly clear, so parents should observe carefully and inform the doctor if there are factors such as trauma.