What causes arm pain?

Ache or pain in the arm can arise from a wide range of causes—some benign and self-limiting, others potentially serious and requiring prompt medical evaluation. Common musculoskeletal origins include muscle strain, tendonitis (such as lateral epicondylitis or “tennis elbow”), bursitis, or rotator cuff injury—particularly if the pain is activity-related, localized, or accompanied by swelling or reduced range of motion. Nerve-related causes include cervical radiculopathy (nerve root compression in the neck), thoracic outlet syndrome, or peripheral neuropathy, often presenting with radiating pain, numbness, tingling, or weakness along a specific nerve distribution.

Importantly, arm pain—especially sudden, severe, or left-sided pain—can be a red flag for cardiac pathology. Acute myocardial infarction may manifest with referred pain to the left arm, shoulder, jaw, or back, frequently accompanied by chest pressure, shortness of breath, diaphoresis, nausea, or lightheadedness. This requires immediate emergency assessment. Other systemic considerations include deep vein thrombosis (DVT) in the upper extremity—often associated with unilateral swelling, warmth, and tenderness—or less common but critical conditions such as aortic dissection or metastatic malignancy involving bone or nerve structures.

A thorough clinical evaluation—including detailed history (onset, character, duration, aggravating/relieving factors, associated symptoms), physical examination (neurovascular assessment, joint mobility, strength, sensation), and targeted diagnostics (e.g., ECG, cardiac biomarkers, imaging such as X-ray, MRI, or ultrasound)—is essential to determine the underlying etiology. Patients should seek urgent care for new-onset, unexplained, or worsening arm pain—particularly when associated with systemic symptoms, trauma, or risk factors for cardiovascular disease.