Left Shoulder Pain: Top 15 Causes (& What to Do)

Left shoulder pain can be caused by several conditions, and is usually a result of inflammation of the tendons or bursa in the shoulder area (which can occur with tendonitis or bursitis). It can also be a sign of pinched nerves in the neck area, or another musculoskeletal condition like rheumatoid arthritis or arthrosis.

Pain in the left shoulder can appear with other symptoms, such as chest pain, tingling sensations or numbness in the left arm. These are more serious symptoms, however, and can be signs of a heart attack or angina, which require urgent medical attention.

If you notice left shoulder pain, you should consult a family doctor or orthopedic surgeon to assess the characteristics of the pain. The doctor may ask questions about what may have caused it as well as if you have other symptoms to determine a diagnosis and initiate treatment. If you notice symptoms of a heart attack or angina, proceed immediately to a hospital.

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What causes left shoulder pain?

The main causes of pain in the left shoulder are:

1. Heart attack

A heart attack is associated with reduced blood flow to the heart, which can lead to heart cell death in the affected area. It causes symptoms like chest pain that can radiate to the neck, jaw, armpit, back, arm, left shoulder or even the right shoulder and arm.

This pain in the chest, shoulder and arm can be accompanied by other symptoms such as dizziness, malaise, nausea, cold sweat or paleness.

Learn more about what causes a heart attack and how it can present.

What to do: If you suspect you are having a heart attack, you should seek medical attention immediately, as this is a serious and life-threatening condition. Treatment is usually initiated immediately, with medication, catheterization or angioplasty to restore blood flow to the heart and avoid complications. 

2. Angina

Angina is characterized by pain, tightness or heaviness in the chest which can radiate to the left shoulder, arm or neck. It is caused by a decrease in blood flow through the arteries that carry oxygen to the heart.

Angina is usually the result of by atherosclerosis, which is the accumulation of fat in the heart arteries, which can be related to factors like diabetes, high blood pressure or a high-fat diet. Symptoms of angina can be triggered by exertion or stressful situations.

What to do: Treatment for angina should be monitored by a cardiologist and depends on the type of angina. Your doctor may prescribe medications like anticoagulants, antiplatelets, vasodilators or beta-blockers to help manage discomfort.

3. Tendonitis

Left shoulder pain can arise from tendonitis, which is inflammation of the tendon. A tendon is the end of the muscle that attaches to the bone, and inflammation can affect the tendons of the rotator cuff or the long head of the biceps.

In addition to pain in the left shoulder, tendonitis can lead to other symptoms such as cramps in the shoulder, weakness or difficulty moving the arm, or a stinging sensation in the shoulder.

Shoulder tendonitis is usually caused by injuries or repetitive strain in people who practice intense physical activity such as basketball, volleyball or tennis, or in professions such as carpenters, teachers or painters.

What to do: Rest the joint and avoid repetitive strain to reduce inflammation of the tendon and relieve pain. You can also apply ice pack to the shoulder for 20 minutes twice a day. In some cases, the doctor may recommend physiotherapy, the use of anti-inflammatory drugs or surgery. 

4. Bursitis 

Left shoulder pain can also be caused by bursitis, which is an inflammation of the subacromial bursa. This is small fluid-filled sac that serves as a cushion between the bones, tendons and muscles of the shoulder to prevent friction.

Bursitis in the left shoulder is usually associated with trauma or repetitive movements of the shoulder, which can happen in athletes or people who work in painting, carpentry or cleaning. It can also arise due to health conditions such as rheumatoid arthritis, lupus or gout.

What to do: You can apply an ice pack to the shoulder for about 20 minutes, 1 or 2 times a day to reduce the inflammation. You should consult an orthopedic surgeon who may recommend treatment with painkillers or anti-inflammatory drugs, physiotherapy, corticosteroid injections into the shoulder joint or even surgery. 

5. Cervical nerve pinching

Left shoulder pain can also occur due to pinching of the cervical nerves located in the neck. This can happen with a cervical hernia or narrowing of the cervical canal, leading to pain in the neck that radiates to the shoulder, arm, hand or fingers. 

Other symptoms include weakness or tingling in one of the arms, difficulty moving the neck or discomfort when raising the arms.

What to do: You should consult an orthopedic surgeon to identify the cause of the pinched cervical nerve and to start the most appropriate treatment. Treatment may include physiotherapy, painkillers and anti-inflammatory drugs. In serious cases, the doctor may recommend surgery. 

6. Shoulder dislocation

Left shoulder pain can be caused by a dislocation, which is an injury in which the joint of the shoulder bone pops out of  its natural position. This can happen with accidents, falls, contact sports or lifting a heavy object incorrectly.

Pain in the left shoulder from a dislocation is intense and is usually accompanied by other symptoms, such as pain that radiates to the arm and neck, difficulty moving the arm, swelling in the shoulder, numbness, weakness or tingling in the neck or left arm. 

What to do: Shoulder dislocations should be treated as soon as possible as advised by an orthopedic surgeon. Depending on the severity of the dislocation, the doctor may manually manipulate the shoulder back in place and indicate the use of medication, or recommend surgery in the most serious cases. 

7. Cervical spondylosis

Cervical spondylosis is characterized by wear and tear of the vertebrae and intervertebral discs of the cervical spine, in the neck region, usually caused by osteoarthritis. It can affect the left or right arm, and lead to symptoms such as neck pain, shoulder pain that radiates to the arms or fingers, weakness in the arms or numbness in the fingers. 

What to do: Treatment for cervical spondylosis begins with the use of analgesics, anti-inflammatories or muscle relaxants, prescribed by the orthopedic surgeon, as well as physiotherapy and, in some cases, surgery. 

8. Fibromyalgia

Fibromyalgia is a chronic rheumatological condition that causes generalized pain throughout the body, as well as increased sensitivity, difficulty sleeping, frequent tiredness, headaches and dizziness, muscle stiffness and numbness in the hands and feet.

This condition can also lead to pain in the muscles and joints of the left shoulder, stiffness or discomfort in the shoulder.

What to do: Treatment should be guided by a rheumatologist who may recommend the use of painkillers or antidepressants, physiotherapy or physical exercise. Learn more about the fibromyalgia medications that your doctor may prescribe.

9. Rotator cuff tear

Left shoulder pain can arise due to a rupture of the rotator cuff. The rotator cuff is a structure in the shoulder that is made up of four muscles. It is responsible for moving and giving stability to the shoulder. Injuries to this area can cause symptoms such as pain in the arm that worsens when moving, weakness in the arm or difficulty in day-to-day activities. 

A rotator cuff tear can occur due to inflammation from wear and tear, irritation or overuse of the joint, as in the case of athletes or people who work carrying weight with their arms

What to do: Treatment should be guided by an orthopedic surgeon and may include resting the shoulder, applying ice, physiotherapy or the use of anti-inflammatory drugs or corticosteroid injections into the joint. 

10. Rheumatoid arthritis

Rheumatoid arthritis is an autoimmune, inflammatory and chronic disease that causes stiffness, pain and swelling in the joints. This condition can affect the left shoulder, causing chronic pain in the shoulder, difficulty moving the shoulder and left arm, or even deformity in the joint.

What to do: Treatment should be guided by a rheumatologist and includes the use of medication, an anti-inflammatory diet and physiotherapy. Treatment goals are aimed at relieving pain and swelling in the joints and improving quality of life. 

11. Diabetic neuropathy

Diabetic neuropathy is a condition that occurs due to prolonged exposure to high blood sugar levels. If left untreated, it can cause progressive damage to the body's nerves. This condition can affect the shoulder, arm and hand on the left and/or right side, leading to symptoms such as acute pain, burning, tingling or numbness.

Diabetic neuropathy is generally more common in people who do not adhere to diabetes treatment and do not participate in regular follow-ups with their doctor.

What to do: You should follow your diabetes treatment as prescribed by your doctor. It usually involves the use of diabetic medications, like insulin, to normalize your blood sugar levels. In addition, to relieve the pain, the doctor may prescribe anticonvulsant, antidepressant or opioid medication, such as pregabalin, amitriptyline or tramadol.

12. Frozen shoulder syndrome

Frozen shoulder syndrome, also known as adhesive capsulitis, is associated with inflammation in the shoulder joint capsule, or the tissue that covers the shoulder joint. This condition can affect the left shoulder, causing pain, shoulder stiffness or limited movement.

Frozen shoulder syndrome can be caused by long periods of immobilization of the shoulder after shoulder, breast or cervical spine surgery, or by health conditions such as diabetes, hyper- or hypothyroidism or Parkinson's disease.

What to do: Treatment should be guided by an orthopedic surgeon, who may prescribe anti-inflammatory drugs, physiotherapy or surgery.

13. Arthrosis

Arthrosis, or osteoarthritis, is a rheumatic disease that causes breakdown of the shoulder cartilage. This decreases the quality, quantity and thickness of this cartilage, causing chronic pain in the left shoulder. This pain can be constant and more intense when moving the arm.

Arthrosis is more common in people over 50 and can be associated with other conditions, as well as excess weight or weakness in the shoulder muscles.

What to do: It's important to consult an orthopedic surgeon who may recommend the use of painkillers, such as acetaminophen, or anti-inflammatories, such as ibuprofen or diclofenac. Physiotherapy sessions are also recommended and, in some cases, the doctor may inject the affected shoulder with corticosteroids or hyaluronic acid. 

14. Thoracic outlet syndrome

Thoracic outlet syndrome can also cause pain in the left shoulder. It occurs due to compression of the nerves and/or blood vessels that are located in the thoracic outlet region, between the collarbone and the first rib.

Generally, thoracic outlet syndrome occurs due to injuries or irritation to these structures from trauma, accidents or repetitive strain. It can lead to symptoms such as pain in the shoulder, arm and neck, a tingling sensation or difficulty moving the arms.

What to do: Treatment should be guided by an orthopedic surgeon, who may recommend the use of painkillers, anti-inflammatory or anticoagulant drugs, physiotherapy or even surgery. 

15. Lung cancer

Lung cancer, especially when it affects the upper part of the lung, can also cause pain in the left shoulder, arm or weakness in the hand. This condition is known as Pancoast syndrome. 

Generally, shoulder pain caused by lung cancer arises because the tumor cells invade the nerves of the brachial plexus (present in the region from the neck to the armpits) or the pleura (the membrane that lines the other lungs).

What to do: Treatment of lung cancer is prescribed by an oncologist, and may involve surgery, chemotherapy or radiation therapy. The treatment approach varies depending on the type of cancer, the size of the tumor, the presence of metastases and the patient's general health status.