Symptoms of polyps include nasal congestion, sinusitis, loss of smell, thick nasal discharge, facial pressure, nasal speech, and mouth breathing. As polyps grow larger, they eventually prolapse into the nasal cavity resulting in symptoms. The most prominent symptom of nasal polyps is blockage of the nasal passage. The exact cause is unclear. They may be related to chronic inflammation of the lining of the sinuses. They occur more commonly among people who have allergies, cystic fibrosis, aspirin sensitivity, or certain infections. The polyp itself represents an overgrowth of the mucous membranes. Diagnosis may occur by looking up the nose.