👉 The term "catarrhal" is a medical term that refers to a type of nasal discharge. It occurs when there is an infection or irritation in the lining of the nose, which can cause swelling and discomfort. The exact cause of catarrhal is not fully understood but it is thought to be caused by inflammation and damage to the lining of the nose. Symptoms may include difficulty breathing, sneezing, and a foul-smelling nasal discharge. Treatment may involve antibiotics or other medications to help