One hand being colder than the other is a symptom of vascular thoracic outlet syndrome, according to Mayo Clinic. Vascular thoracic outlet syndrome is caused by the compression of nerves or blood vessels located between the collar bone and the first rib.
Common triggers of vascular thoracic outlet syndrome include poor posture, an anatomical defect, an injury traumatic enough to cause internal changes and pinch the nerves, repetitive activity, pressure on joints, and pregnancy, notes Mayo Clinic. Surgery is usually not recommended to treat this condition unless it becomes severe enough to cause serious nerve damage. Many patients see improvement using physical therapy to strengthen and stretch the shoulder muscles, which allows the thoracic outlet to open. Prescribed medications such as ibuprofen or muscle relaxants can be helpful as well.
Raynaud's disease has also been known to cause cold or numb feelings in the hands and fingers, but usually in both hands instead of just one, according to Mayo Clinic. Raynaud's is more common in women, especially those exposed to cold weather, and can be brought on by stress or cold temperatures. A typical episode of Raynaud's disease lasts about 15 minutes total, after which the hands return to normal.