Your nose keeps running because of irritation or inflammation inside the nose, which causes it to produce extra mucus that drips out. Common reasons include infections like the cold or flu, allergies, exposure to cold or dry air, irritants like smoke, or nasal conditions such as sinusitis or nasal polyps. Sometimes, a runny nose can be due to nonallergic rhinitis, where the nose reacts excessively to triggers like pollution, spicy foods, or temperature changes. Other causes may be certain medications, hormonal changes, or even a foreign object in the nose. The running nose is your body's way of trapping and flushing out irritants or infections. Usually, a runny nose goes away on its own, but if it persists for a long time or is accompanied by severe symptoms, it might need medical evaluation to rule out underlying causes like chronic rhinitis or infections requiring treatment.