Shoulder and neck soreness can be caused by many reasons, local muscle chronic strain is a more common cause. Keeping a posture for a long time or doing the same action repeatedly for a long time, muscle strain will trigger localized shoulder and neck soreness, which can be relieved by local hot compress or massage. In addition, local lactic acid buildup, shoulder cold, cervical spondylosis, diseases around the shoulder joint, etc., may cause shoulder and neck soreness. 1. Local lactic acid buildup: If the patient does not exercise for a long time and occasionally goes to do exercise, such as playing badminton, the local soreness of shoulder and neck will be more obvious after coming back, this is because local lactic acid buildup, not yet metabolized, lactic acid after a few days of metabolism, the soreness can gradually improve. 2. Shoulder Some people may experience shoulder and neck swelling after sleeping or resting without keeping the shoulder warm, which can be relieved by local massage or hot compress. Some patients may just feel sore and swollen when their early symptoms are not typical. In addition, diseases such as soft tissue injury in the shoulder, tumors in the shoulder and neck or oral cavity, etc., which squeeze the surrounding muscles can also cause soreness and swelling in the shoulder and neck. If the disease continues to develop, it will also show other symptoms, such as radiating pain, radiating pain and numbness along the neck and shoulder to the upper extremities, or even inability to complete fine finger movements, etc. When these symptoms appear, it is recommended to seek medical treatment in a timely manner.