A cough is a protective reflex that helps clear the airways of mucus, irritants, or foreign particles, and it can be either acute or chronic depending on its duration. Acute coughs are commonly caused by respiratory infections such as the common cold, influenza, or bronchitis, while chronic coughs—lasting more than several weeks—may result from asthma, acid reflux, smoking, allergies, or underlying lung conditions. Coughs may be dry and nonproductive or productive with mucus, and they can be accompanied by symptoms such as sore throat, chest discomfort, wheezing, or shortness of breath. Although many coughs resolve on their own, persistent, severe, or worsening coughs—especially those with blood, weight loss, or breathing difficulty—should be medically evaluated to determine the underlying cause.