Pain in the upper arm is a common complaint that can stem from a wide variety of sources. This discomfort can range from a minor ache to a sign of a significant underlying condition. Determining the precise cause relies heavily on the quality of the pain and any accompanying symptoms, such as stiffness, numbness, or weakness. The pain may be localized in the arm’s muscle or bone, or it may be referred from an entirely different part of the body.
Muscular Overuse and Acute Injury
The most direct sources of upper arm pain involve the muscles and tendons, specifically the biceps and triceps. Overuse injuries commonly manifest as tendonitis, which is the inflammation of the cords connecting muscle to bone. Biceps tendonitis, affecting the tendon near the shoulder or elbow, causes pain that typically worsens with lifting or overhead activities.
A sudden, forceful exertion can lead to an acute muscle strain or tear, involving micro-tears in the muscle fibers. Symptoms usually include immediate sharp pain, tenderness, and sometimes noticeable bruising or swelling. The pain from a muscle strain is generally localized and intensifies when the affected muscle is contracted or stretched.
Pain Originating in the Shoulder Joint
Many instances of upper arm discomfort are symptomatic of a problem within the shoulder joint, even if the pain is felt further down the humerus bone. Rotator cuff issues are a frequent source, often involving impingement, where tendons are pinched between the bones during movement. This leads to chronic, dull aching that becomes sharp when the arm is lifted overhead or rotated.
Another common inflammatory condition is bursitis, involving the bursa—a small, fluid-filled sac that cushions the joint. When the bursa becomes irritated, typically from repetitive motion, the resulting inflammation causes pain that can radiate into the upper arm. Adhesive capsulitis, often called frozen shoulder, causes pain and progressive stiffness as the joint capsule thickens and tightens, restricting the ability to raise the arm or reach behind the back.
Radiating Pain from Pinched Nerves
Upper arm pain presenting as a shooting sensation or accompanied by changes in feeling often points to a neurological cause known as radiating pain. Cervical radiculopathy occurs when a nerve root in the neck (cervical spine) becomes compressed or irritated, usually due to a herniated disc or degenerative changes like bone spurs. Since these nerves travel directly into the arm, compression causes symptoms to extend along that specific nerve pathway.
The pain is frequently described as electric, sharp, or burning, sometimes traveling all the way down to the hand. This discomfort is often accompanied by paresthesia, which is a sensation of tingling or “pins and needles,” or by muscle weakness in the arm or grip. Thoracic Outlet Syndrome (TOS) is another potential cause, involving the compression of nerves or blood vessels near the collarbone and first rib. This type of nerve compression can also produce pain, numbness, and weakness that tracks into the upper arm.
Referred Pain from Systemic Conditions
In certain situations, pain felt in the upper arm originates not from a local injury but from an organ elsewhere in the body, a phenomenon known as referred pain. The most serious example involves the heart, where conditions like angina (reduced blood flow) or a myocardial infarction (heart attack) can present as pain in the arm. This occurs because the sensory nerves from the heart and the arm enter the spinal cord at similar levels, causing the brain to misinterpret the source of the distress.
This type of pain is often felt in the left arm, though it can occur in the right arm or both, and is typically described as a dull ache, pressure, or heaviness. Crucially, cardiac-related arm pain is almost always accompanied by other warning signs that demand immediate medical attention. These symptoms can include chest pressure, shortness of breath, nausea, cold sweats, or pain that radiates into the jaw or back. If upper arm pain is sudden, severe, and combined with any of these systemic symptoms, it constitutes a medical emergency.