The common causes of runny nose include acute rhinitis, chronic simple rhinitis, allergic rhinitis, sinusitis and so on. 1. Acute rhinitis: it will lead to swelling and congestion of the nasal mucosa and glandular hyperplasia under the mucosa, which will be manifested as nasal congestion, sneezing, watery nasal discharge, and decreased sense of smell, etc. Chronic simple rhinitis: it can be caused by repeated episodes of acute rhinitis or incomplete treatment. 2. Chronic simple rhinitis: it can be caused by repeated episodes of acute rhinitis or incomplete treatment. The course of the disease may last for several months or have repeated attacks. Its main manifestations include swelling of nasal mucosa, increased nasal discharge, nasal congestion and so on. 3. Allergic rhinitis: allergens in the environment can induce this disease. Typical symptoms are watery nasal discharge, paroxysmal sneezing, itchy nose, nasal congestion and so on. 4. Sinusitis: including acute sinusitis, chronic sinusitis, mainly manifested as yellow purulent nasal discharge, nasal congestion, dizziness, dizziness, decreased sense of smell and so on. If you always have a runny nose, it is recommended to consult a doctor in time for a clear diagnosis and symptomatic treatment.