Patients with polymyositis who have been suffering from the disease for more than 10 years may now have severe coughing symptoms related to polymyositis combined with interstitial pneumonia, which needs to be diagnosed and treated with medication, surgery and other treatments. Polymyositis mainly affects the skeletal muscles of the patient, and the typical symptoms are weakness of pharyngeal and cervical muscles, joint pain and proximal weakness of limbs. When the disease involves the lungs, it will lead to related respiratory symptoms, and some of the patients may be combined with interstitial pneumonitis, which may lead to coughing, chest tightness and other symptoms, which need to be diagnosed clearly and then treated with medications, surgeries, and other therapies. Treatment of polymyositis combined with interstitial pneumonia is based on drug therapy, commonly used drugs include codeine, dextromethorphan and other cough suppressants and glucocorticoids such as prednisone and methylprednisolone, and immunosuppressants such as methotrexate and azathioprine, which are supplemented by other treatments such as oxygen therapy, nutritional support and, if necessary, surgical treatment. Drugs need to be used under the guidance of a physician, it is recommended that patients with polymyositis whose condition has changed go to the rheumatology and immunology department of a regular hospital and follow the doctor’s instructions to avoid delays in their condition.