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 suggest overuse of shoulder muscles, excessive loading, or weather-related factors (e.g., cold, damp conditions).

2. Infectious shoulder joint disorders: In addition to typical shoulder pain, these infections may present with systemic signs such as high fever and chills, along with local inflammatory manifestations. Movement of the affected shoulder joint 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 multi-system involvement, necessitating evaluation by 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 be highly vigilant for early signs of myocardial infarction or angina pectoris, as cardiac pain may radiate to the left shoulder, manifesting solely as shoulder discomfort. Because left shoulder pain may be the initial symptom, misdiagnosis or delayed diagnosis—and consequent treatment delay—can occur.