There are many causes of hemoptysis, but the most common ones are bronchiectasis, tuberculosis, and lung cancer. The symptoms of bronchiectasis are often obvious, that is, coughing for a long time, coughing a lot of yellow sputum, when there is hemoptysis, we should consider whether the hemoptysis is caused by bronchiectasis. If a patient has fever, especially low to moderate fever, night sweats, loss of weight, weakness, and hemoptysis, he must pay attention to pulmonary tuberculosis. If hemoptysis occurs at an older age, and there were no such symptoms in the past, we should pay high attention to whether there is a tumor, especially lung cancer, which can cause such hemoptysis. Of course, if there is a clear history of cold and sudden onset of violent coughing, such coughing is generally not to be feared, as it is usually a viral or bacterial infection, and if the violent coughing causes the rupture of local capillaries, it can also cause a small amount of hemoptysis, which can heal spontaneously. This can heal on its own.