There are many reasons for thick phlegm and thick nasal mucus, such as common cold, acute sinusitis, bronchitis and so on. 1. Common cold: the common cold can start with clear mucus, and when it gets better, there can be thick and sticky nasal mucus, accompanied by nasal congestion, cough and other phenomena; secondary bacterial infection, resulting in nasal mucosa, pharyngeal mucosal congestion, edema, there will be a thick phlegm and thick nasal mucus phenomenon. 2. Acute sinusitis: acute attack of sinusitis can cause nasal mucosa congestion, edema, increased secretion, mainly purulent nasal discharge, nasal discharge backflow to the pharynx can form thick phlegm, so there will be thick phlegm and thick nasal discharge. 3. Bronchitis: Bronchitis patients in the bacterial infection, there will be thick sputum accompanied by thick nasal discharge, at the same time there will be cough, nasal congestion, chest tightness, throat itching and other phenomena. There are many reasons for thick phlegm and thick nasal discharge, and it is recommended to go to the hospital in time to improve the examination and take standardized treatment according to the doctor’s instructions.