Pain in the left arm and shoulder can range from minor muscle strain to a medical emergency. Understanding its potential causes is important for distinguishing between urgent and less urgent conditions. The pain’s quality, accompanying symptoms, and triggers often provide valuable clues about its source.
Cardiac-Related Causes
Left arm and shoulder pain can indicate cardiac issues, particularly a heart attack (myocardial infarction) or angina. A heart attack occurs when heart muscle is damaged from insufficient oxygen, often due to blocked coronary arteries. Pain may manifest as chest discomfort lasting more than a few minutes, radiating to the left arm, shoulder, back, jaw, or teeth, often described as tightness, squeezing, or crushing pressure. Other symptoms include shortness of breath, sweating, dizziness, nausea, vomiting, or weakness.
Angina, a symptom of coronary artery disease, involves chest pain from reduced blood flow to the heart. This pain can spread to the arms, neck, jaw, shoulders, or back. Angina symptoms might also include shortness of breath, dizziness, fatigue, nausea, or sweating. Referred pain explains why cardiac issues cause left arm and shoulder pain; nerves from the heart share spinal cord pathways with arm and shoulder nerves, leading the brain to misinterpret the pain’s origin.
Musculoskeletal and Joint Causes
Many common causes of left arm and shoulder pain stem from musculoskeletal and joint issues. Rotator cuff injuries, involving muscles and tendons stabilizing the shoulder, are frequent culprits. These injuries cause a dull ache deep in the shoulder, often worsening at night or when lying on the affected side. Pain may occur when lifting or rotating the arm, along with weakness and sometimes a crackling sensation.
Bursitis, inflammation of a bursa (fluid-filled sacs cushioning joints), can cause shoulder pain. Symptoms include pain when moving the arm, tenderness, swelling, and sometimes redness. Pain may radiate down the arm and often intensifies when lying on the affected shoulder or performing overhead movements. Frozen shoulder (adhesive capsulitis) causes pain and stiffness in the shoulder joint, gradually worsening, and can severely limit range of motion. The condition involves thickening and tightening of the shoulder capsule, leading to adhesions and reduced synovial fluid.
Arthritis, inflammation of joints, is another common cause of shoulder and arm pain. Osteoarthritis, where cartilage breaks down, results in pain that worsens with activity. This can lead to stiffness, limited motion, and grinding sounds (crepitus) when moving the shoulder. Rheumatoid arthritis, an autoimmune disease, causes the immune system to attack joint tissues, leading to pain, swelling, and stiffness in the shoulder, often affecting both sides of the body.
Nerve-Related and Referred Pain
Nerve issues can contribute to left arm and shoulder pain through direct compression or referred pain from internal organs. Nerve compression, such as cervical radiculopathy, occurs when a nerve in the neck is pinched, often due to a herniated disc or spinal stenosis. This results in pain, numbness, tingling, or weakness extending into the arm and hand. Thoracic outlet syndrome involves compression of nerves or blood vessels between the collarbone and first rib, leading to similar arm symptoms.
Referred pain from internal organs can also manifest in the left arm or shoulder due to shared nerve pathways. For example, irritation of the diaphragm, often from a ruptured spleen, can cause left shoulder pain (Kehr’s sign). This happens because the phrenic nerve, which innervates the diaphragm, shares cervical nerve origins with supraclavicular nerves supplying the shoulder area. Conditions affecting organs like the stomach, liver, or gallbladder can also sometimes refer pain to the shoulder region.
When to Seek Medical Attention
Knowing when to seek medical attention for left arm and shoulder pain is crucial. Immediate emergency care is warranted if pain comes on suddenly, is severe, or is accompanied by chest pressure, fullness, or squeezing. Other red flag symptoms include difficulty breathing, sweating, dizziness, nausea, vomiting, or pain radiating to the jaw or back. Emergency care is also necessary if the arm or shoulder appears deformed, is badly swollen, or if there is no ability to move the arm after an injury.
For less acute but persistent symptoms, a medical consultation is advisable. This includes pain that worsens or does not improve after a couple of weeks, pain limiting daily activities, or pain accompanied by swelling, redness, tenderness, or warmth around the joint. If you experience persistent numbness or tingling, or a sudden injury with a snapping sound, see a healthcare provider. A doctor can help determine the underlying cause and ensure appropriate treatment.