What Causes Soreness and Pain in the Left Shoulder?

Left shoulder soreness and pain are relatively complex, and we may consider the following five potential causes:

1. Cervical–shoulder pain caused by trauma: Immediate onset of left shoulder joint pain, swelling, and functional impairment following trauma—possibly accompanied by fracture. Recurrent left shoulder joint pain may be attributable to overuse of shoulder muscles, excessive load-bearing, or cold/damp weather.

2. Pain due to infectious shoulder joint disorders: In addition to common shoulder joint pain, such infections may present with high fever, chills, and other signs of systemic inflammation. Movement of the affected shoulder joint typically elicits marked pain, regardless of direction.

3. Pain secondary to other systemic diseases: For example, rheumatoid arthritis and systemic lupus erythematosus are autoimmune disorders. Left shoulder joint pain associated with these conditions is often accompanied by manifestations in other organ systems; patients should therefore consult a rheumatologist or immunologist.

4. Metabolic disorders may also cause left shoulder joint pain—for instance, osteoporotic arthropathy or osteoarthritis secondary to thyroid or parathyroid disease.

5. Patients presenting with left shoulder joint pain must remain highly vigilant for early signs of myocardial infarction or angina pectoris, as referred pain from cardiac ischemia may radiate to the left shoulder. Since left shoulder pain may be the initial symptom, misdiagnosis or delayed diagnosis may occur, potentially compromising timely treatment.