Signs of deterioration of small cell lung cancer usually include cough, hemoptysis, circulatory respiratory failure, distant metastasis and other manifestations. 1. Cough: when small cell lung cancer patients deteriorate, the tumor will involve the large airways, leading to obstructive pneumonia caused by obstruction of large airways, which may result in coughing, accompanied by fever, shortness of breath, wheezing and wheezing. 2. Hemoptysis: there are abundant blood vessels in lung tissues, whether small pulmonary veins, small arteries, or bronchial arteries, when tumor infiltration invades blood vessels, or blood vessels supplying the tumor rupture, it will easily lead to symptoms of bleeding and hemoptysis. 3. Respiratory and circulatory failure: cancer cells of small cell lung cancer patients are not only confined to one side of the patient’s chest cavity, but also cause cancerous pericardial effusion when it worsens. This situation will lead to partial or complete obstruction of blood flow back to the heart, and then patients will suffer from circulatory and respiratory failure. 4. Distant metastasis: small cell lung cancer is prone to early distant metastasis, such as brain metastasis and liver metastasis. Patients with brain metastasis may suffer from headache, nausea, vomiting, vision loss and other symptoms. It is suggested that patients with small cell lung cancer should consult doctor in time and take appropriate treatment under doctor’s guidance.