The main symptoms of polymyositis are muscle weakness, skin rash and joint pain. 1. Muscle weakness: Polymyositis is an autoimmune inflammatory disease of the muscles. The persistent inflammatory reaction in the muscles may affect the muscles, nerves and calcium ion imbalance, which leads to muscle weakness. 2. Rash: The patient may have a positive rash, usually on the upper orbital region of the face and the back, which is usually dark purple or dark red, sensitive to light, and can also appear on joints such as the hands and feet. 3. Joint pain: The autoimmune inflammatory response can also accumulate in the large and small joints, causing localized oozing, edema, and pain in the joints. Other clinical symptoms of polymyositis, such as diarrhea and gastrointestinal bleeding, may also occur. It is recommended to go to the hospital if you experience any of the above symptoms.