Coughing. Coughing up phlegm, infectious germs, and foreign substances is one of the ways in which the lungs protect themselves. Severe coughing, however, may signal lung disease. Obstructive diseases of the lungs (asthma and COPD) and lung cancer often cause a person to cough up phlegm, which, if yellow or green, may signal an infection. Coughing up blood is a critical sign, especially in a current or former cigarette smoker. It may suggest a potentially life-threatening disease, such as lung cancer or pulmonary embolism, although it can also be a sign of a less serious lung problem such as bronchitis.
Noisy breathing. Noisy breathing is an especially common sign of lung disease. Abnormal sounds range from a high-pitched crowing during inhalation to continuous musical sounds during exhalation (wheezing, which occurs with asthma and some other disorders). The maxim all that wheezes is not asthma underscores the fact that many health conditions, including diseases of the larynx, heart failure, pulmonary embolism, and COPD, can cause wheezing. Repetitive loud snoring during sleep, interrupted by periods of silence in which theres no air flow, is a major sign of sleep apnea.
Chest pain. Chest pain or other discomfort has numerous causes, and determining whether the cause is a heart, esophageal, or lung disease is often challenging. Pain on one side of the chest that worsens with deep breathing, coughing, or laughing suggests pleurisy, an inflammation of the pleura (the membrane around the surface of the lungs and the inner chest wall). Pleurisy may be caused by a viral infection, pneumonia on the outer surface of the lung, pulmonary embolism, cancer, or a systemic (affecting the entire body) inflammatory disease such as systemic lupus erythematosus. Alternatively, pain that worsens on inhalation may be due to a chest wall injury such as a broken rib.