When you’re sick or your lungs have become irritated, your body reacts by coughing. This is your body’s defense mechanism to clear out any mucus, allergens, or pollutants so that you don’t keep breathing it in. Coughing is usually nothing to be concerned about. When a cough is a symptom of a cold, it tends to clear up on its own within two or three weeks. A lingering cough or a chronic cough not brought on by a recent cold can be an indicator of a more serious condition. Coughs that last longer than eight weeks for adults, or four weeks in children, are considered.