There are many causes of left shoulder pain, such as left shoulder trauma, left shoulder bone degeneration or left shoulder frozen shoulder, tendon cuff injury and cervical spondylosis, all of which can cause pain in the left shoulder. During the painful period, you should limit the activities of the shoulder joint and pay more attention to keep warm to avoid getting cold, so as not to aggravate the pain in the left shoulder. During the pain period, you can apply heat to the left shoulder area to promote blood circulation in the left shoulder area and to relieve the spasm of the soft tissues in the left shoulder, which will help to relieve the pain. When the pain is obvious, you can take oral non-steroidal anti-inflammatory drugs, such as Nimesulide, Ibuprofen, Diclofenac sodium, etc., to temporarily relieve the pain.