A cough is a natural protective reflex that helps clear the airways and lungs by removing mucus, dust, smoke, germs, or other irritants. It is one of the most common symptoms affecting people of all ages and is usually a sign of an underlying respiratory or medical condition. A cough may be dry (without mucus) or productive (with mucus or phlegm). It can last for a few days, several weeks, or even months depending on the cause.
Doctors generally classify a cough as acute (lasting less than 3 weeks), subacute (lasting 3–8 weeks), or chronic (lasting more than 8 weeks). Common causes include viral infections such as the common cold or influenza, bacterial infections, allergies, asthma, smoking, air pollution, acid reflux (GERD), and chronic lung diseases. A productive cough may produce clear, yellow, green, or blood-stained mucus, which can provide important clues about the underlying condition.
Patients with a cough may also experience sore throat, chest discomfort, wheezing, shortness of breath, nasal congestion, fever, or fatigue. Doctors diagnose the cause of a cough based on medical history, physical examination, and, when necessary, investigations such as a chest X-ray, sputum examination, pulmonary function tests, or blood tests.
Most mild coughs caused by viral infections improve with adequate rest, hydration, and supportive care. However, a persistent cough should not be ignored, especially if it interferes with daily activities or sleep. Early diagnosis and appropriate treatment help relieve symptoms, prevent complications, and identify serious underlying conditions such as pneumonia, tuberculosis, or lung disease.
A cough can be caused by the common cold, influenza, COVID-19, allergies, asthma, bronchitis, pneumonia, tuberculosis (TB), smoking, chronic obstructive pulmonary disease (COPD), acid reflux (GERD), sinus infections, air pollution, dust exposure, lung infections, certain medications (such as ACE inhibitors), and lung cancer. The underlying cause should be identified through proper medical evaluation.
Seek immediate medical attention if a cough lasts for more than three weeks, is accompanied by high fever, difficulty breathing, chest pain, coughing up blood, significant weight loss, persistent wheezing, bluish lips or face, or severe shortness of breath. Children, older adults, and people with chronic lung or heart diseases should also consult a healthcare provider if the cough becomes severe or does not improve with appropriate treatment.