runny nose

A runny nose occurs when the membranes lining your nasal passages produce excess mucus, often due to irritation or infection. This increased mucus helps trap and flush out harmful substances like bacteria, viruses, or allergens. It also causes the blood vessels in the nose to expand, leading to swelling and increased fluid production. Common causes include colds, allergies, or irritants like smoke. While uncomfortable, a runny nose is usually a natural response to help your body clear unwanted particles and pathogens. It often improves with rest, hydration, and appropriate treatment for underlying causes.