What are the causes of underarm pain after shoulder injury?

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It is sometimes hard to determine the exact origin or cause of bodily aches and pains. According to FightingFatigue.com, pain researchers suggest that the origin of all pain is inflammation (pain and swelling) and the body’s response to it.

It would make sense then, that inflammation and your body’s response to it could be one of the causes of underarm pain after shoulder injury.

The Shoulder Joint

The shoulder joint is a complex arrangement of muscles, bones and tendons which allows for a large range of motion for your arm. Unfortunately, a side effect of this extensive mobility is increased potential for injury. The three bones of the shoulder include the scapula (shoulder blade), the humerus (upper arm bone) and the clavicle (collarbone). There are four muscles found in the shoulder joint with tendons connecting to the bones, to allow for movement of your arm.

Shoulder Injuries

The two main causes of most shoulder injuries are degeneration or wear and tear and excessive force or exerting too much strain on the shoulder muscle tendons. Due to the tendinous (consisting of tendons) nature of the shoulder joint, it receives little in the way of blood supply. Shoulder problems are common in the elderly due to the lack of blood supply, which can also prolong the healing process when an injury occurs. Excessive-force injuries typically occur when you try to lift a heavy object or when force is applied to the arm when it is in an unusual position.

Radiating Pain

It is not uncommon for pain from an acute or chronic injury to travel to surrounding areas of the body. That is partly what makes it so difficult at times, to pinpoint the origin of the pain or injury when it is not outwardly apparent. Radiating pain, such as underarm pain after shoulder injury can be due to nerves getting pulled or pinched, causing pain along the entire nerve. Travelling pain can also be the body’s attempt to protect the injured region by overburdening nearby areas.

Causes of Underarm Pain

Shoulder joint injuries can result in something as minor as muscle inflammation with no permanent damage or a partial or complete tear in a muscle that may require surgery to repair it. Either way, the inflammation and discomfort created by a shoulder injury can spread to nearby areas such as the neck, chest, upper arm and underarm. The scar tissue from an improperly healed tear in a shoulder joint muscle can cause underarm pain and discomfort with certain motions. A common shoulder problem known as bursitis (inflammation of bursa) can cause pain to be passed on to the neck, arm and underarm.


Stretching and strengthening of the shoulder joint conditions the muscles and tendons, while helping to prevent shoulder injuries. On a website like thestretchinghandbook.com you can find a couple of beneficial stretches for the shoulder area. The earlier a shoulder injury is treated properly, the speedier your recovery will be and the less likely a similar injury will recur.


There are other more serious causes for both shoulder and underarm pain, such as a heart condition or an impending heart attack. Even if you have suffered a shoulder injury, do not assume that underarm pain is directly related to the injury. Consult with a medical doctor to rule out other possible causes that could include: inflammation of the lymph nodes (in the armpit), pulled muscle or muscle strain, rheumatoid arthritis, allergies, AIDS, Leukemia, cancer, swelling of the axillary lymph nodes and infectious mononucleosis.