Coughing for one month is not necessarily lung cancer, but may also be caused by pneumonia, bronchitis, pleurisy and other diseases. 1. Lung cancer: it is a common malignant tumor in clinic, which mainly manifests as coughing, mainly irritating dry cough, and there may be no or little sputum, with the progress of the disease, there may be metallic sounding cough or choking cough, which may be accompanied by chest pain, hoarseness and other symptoms. 2. Pneumonia: mainly manifested as coughing, coughing up sputum, may be accompanied by fever, loss of appetite, generalized pain, fatigue and other symptoms. 3. Bronchitis: it is a non-specific inflammation of the bronchial mucosa, mainly characterized by coughing, coughing up sputum, and sputum is mostly mucus sputum and other symptoms. 4. Pleurisy: it is an inflammation that occurs in the pleural cavity, mainly characterized by symptoms such as chest tightness and chest pain, which may be accompanied by cough and sputum. Coughing for a month has more causes, we should go to the hospital in time, identify the causes and take symptomatic treatment to avoid delaying the condition. Daily attention should be paid to a light diet, avoid spicy stimulating food.