Runny yellow nose, i.e. pus, may be due to sinusitis, acute rhinitis secondary to bacterial infection, nasal foreign body with infection and other reasons. 1. Sinusitis: this disease is usually secondary to acute rhinitis, allergic rhinitis and other diseases, and is related to bacterial infections such as pneumococcus, hemolytic streptococcus, and other bacterial infections, inflammatory stimulation will lead to an increase in nasal secretions, and a large amount of thick yellow nasal mucus will appear in the nasal cavity. 2. Acute rhinitis secondary to bacterial infection: the disease is usually caused by viral infections, such as adenovirus, rhinovirus, etc., secondary to bacterial infections, the symptom of thick yellow nasal discharge can occur. 3. Nasal foreign body: the disease generally refers to the presence of insects, beads and other foreign bodies in the nasal cavity, the foreign body retained for a long time, secondary bacterial infection, which will lead to an increase in sticky nasal mucus, yellow color. Runny nose is related to many diseases, and it is recommended that patients go to the hospital in time for a clear diagnosis after systematic examination.