Upper arm pain may be related to physiological factors such as cold or a prolonged posture, but also the manifestation of many diseases, such as cervical spondylosis, frozen shoulder, tendonitis, brachial plexus neuritis or trauma to the upper arm caused by the need to identify the cause of the disease and timely treatment. 1. Physiological factors: cold or a prolonged period of time in one position is more common physiological factors that can cause spasm of the muscles of the upper arm and produce more lactic acid substances, triggering pain, through self-conditioning, hot compresses, most of which can be relieved. 2. Cervical spondylosis: when the intervertebral disc of the cervical spine compresses the nerve root on one side, it will cause radiating pain in the upper arm. 3. Frozen shoulder: Frozen shoulder causes adhesion and oozing of the tissues around the joint, which will involve the upper arm and lead to soreness. 4. Tendonitis: There are more tendons in the upper arm, and when aseptic inflammation occurs, it may also lead to soreness. 5. Brachial plexus neuritis: When the brachial plexus nerves are stimulated by inflammatory substances, it is also a factor that causes upper arm soreness. 6. Upper arm trauma: When the upper arm is sprained or contused, the local tissues will become congested and edematous, which will also cause soreness. Upper arm pain in the exclusion of physiological factors, the need for timely consultation to identify the cause of the disease, in accordance with the doctor’s instructions for treatment.