Soreness in the right arm is not a precursor to disease. The most common cause of soreness is muscle strain or synovitis in the right arm itself, such as muscle soreness due to excessive activity in the right hand or prolonged weight bearing. It may also be caused by cervical spondylosis, which is related to herniated cervical discs or osteophytes causing pressure on the spinal cord or nerve roots, mostly accompanied by soreness and pain in the neck and shoulders as well as numbness in the upper limbs. Soreness in the right arm is due to frozen shoulder and may be accompanied by limited shoulder joint movement. Patients with a history of cancer themselves, such as lung cancer, thyroid cancer, or stomach cancer, who experience persistent right arm soreness and swelling as well as pain in other areas, consider whether the soreness is caused by bone metastasis from cancer or may be caused by enlarged lymph nodes compressing nerves.