The main causes of sore throat and runny nose are colds, sinusitis and allergic rhinitis. 1. Colds: Colds are usually caused by bacterial, viral and other pathogenic microorganisms, nasal mucosal glands are stimulated by inflammatory factors to increase secretion of runny nose, and the sensory nerves in the throat are stimulated to cause the symptoms of sore throat. 2. Sinusitis: The main symptoms of sinusitis are nasal congestion, runny nose, headache and loss of smell. Because the nasal cavity is connected to the throat, when the secretion of postnasal drip, snot backflow into the throat, throat inflammation can produce sore throat. 3. Allergic rhinitis: If you suffer from allergic rhinitis, the nasal cavity produces an immune response, and under the action of histamine and other immune factors, you will have a runny nose. Open-mouth breathing caused by nasal congestion induces dryness of the mucous membrane of the throat, which can produce pain. If you have a sore throat or runny nose, you should go to a regular hospital in time to find out the cause of the disease and choose a suitable method of treatment under the guidance of a professional doctor.