Nasal phlegm, which refers to thick secretions in the nasal cavity, may be caused by acute and chronic rhinitis, sinusitis, allergic rhinitis, malignant tumors and other diseases. 1. Usually acute and chronic rhinitis may cause acute and chronic inflammation of the mucosa of the nasal cavity, resulting in increased nasal discharge, accompanied by sneezing, headache, decreased sense of smell, nasal congestion and other symptoms. It is recommended to apply nasal spray hormone, or decongestant under the guidance of the doctor for relief treatment. 2 If you suffer from sinusitis, it may cause mucopurulent discharge, nasal congestion, decreased sense of smell, and pain in the cheeks. 3. Allergic rhinitis usually results in a large amount of white, watery or mucusy nasal discharge, accompanied by sneezing, decreased sense of smell, itchy nose and other symptoms. 4. Malignant tumors of the sinuses or nasal cavity can also lead to a large increase in the amount of pus or pus-blood snot in the nasal cavity. It is recommended that if any of the above symptoms appear, you should go to the hospital in time for diagnosis and symptomatic treatment, so as not to delay the condition.