Left Shoulder Pain:10 Common Causes with Treatment

Left shoulder pain refers to the feeling of pain on the left side of your body, specifically around the upper arm and armpit. This condition is also called armpit or lateral side pain of the arm due to its location in the armpit area.

The left shoulder can be triggered by various factors and usually involves the left side of your body – from your left arm to your left shoulder and even your left side ribs.

In most cases, this pain does not indicate something is wrong with the left side of the body; it could just be strain or overexertion. However, in some cases, this pain may indicate an underlying medical condition such as heart problems.

This article covers everything you need to know about left shoulder pain and its potential causes, symptoms, diagnosis, and treatments.

left shoulder pain
Left Shoulder Pain: Symptoms, Causes, and Treatment

Symptoms of left shoulder pain

The shoulder is one of the most complex joints in the human body. It consists of several bones and muscles that work together to allow a wide range of motion. Because of this, the shoulder is prone to several different types of injuries and conditions.

People with left shoulder pain may experience one or more symptoms. The severity of the symptoms may vary from person to person.

  • Pain: Pain is the most common symptom of shoulder pain on the left side. The pain may be dull and aching or sharp and throbbing.
  • Swelling: Swelling in the armpit area is a common symptom of armpit pain.
  • Numbness: Pain in the armpit area may cause numbness in the fingers, hand, and forearm.
  • Weakness: You may suffer from weakness in the hand and arm.
  • Limitation in movements: This pain can limit the range of activities in the arm.

10 Common Causes of left shoulder pain

There are many causes of left-side shoulder pain, such as heart problems, swelling of the lymph nodes, nerve irritation, or a direct injury to the structures in the armpit area. The following are some of the common causes.

1. Soft Tissue Damage

Soft tissue damage to the muscles and joints is the most common cause of left shoulder pain. This is more likely to happen if you do excessive weight lifting or have an injury to the upper left arm.

Left shoulder pain can also be caused by inflammation in the joints of the upper arm, such as tennis elbow or golfer’s elbow. This can result from repetitive use of the muscles in the upper arm, such as when playing sports or doing heavy lifting.

Left shoulder pain can also be caused by a rotator cuff tear, where the muscles in the upper arm become overstretched and torn. This can happen due to age, sports injuries, or trauma.

The pain caused by soft tissue damage is usually described as a dull ache that worsens with movement and lifting. It can also be accompanied by swelling and tenderness in the upper arm.

A sprain is another cause of shoulder pain on the left side. This condition refers to a stretch or tear of a ligament. The ligaments are the tissues that connect bones to other bones.

Sprains can occur when an injury stretches the ligament beyond its normal limits. Sprains are most common in the shoulder joint and the knee joint.  A sports massage, anti-inflammatory drugs, and a RICE treatment can be helpful for a sprain.

2. Heart problems

Shoulder pain in the left can result from a heart attack, fluid around the heart, or a rupture in the heart wall. This pain can sometimes occur before the onset of more severe heart problems, so it is essential to report any changes in your left shoulder pain to your doctor.

Shoulder pain on the left side can occur if there is an obstruction in the blood flow from the heart. This may be due to a blood clot, an abnormal growth in the heart (a tumor), a tear in the heart wall, or a strange connection between the arteries and veins in the lungs.

Shoulder pain in the left can also be caused by a heart rhythm problem, such as atrial fibrillation. This condition is where the heart beats irregularly and can cause blood to pool in the left shoulder area.

3. Lung problems

Lung problems can cause shoulder pain in the left due to fluid build-up in the lungs, called pulmonary edema. The fluid can build up because of heart failure or fluid accumulating around the lungs due to a lung infection.

This pain can also indicate an infection in the lungs. This might be due to a bacterial or viral infection or an infection from fungi.

The infection may also be due to an autoimmune disorder, where the body mistakenly attacks its tissues. This pain can also be caused by a blood clot forming in the veins of the lungs (a pulmonary embolism).

This is more commonly associated with right shoulder pain. Left shoulder pain caused by lung disease is often described as a deep, achy pain that moves across the upper back and down the left shoulder.

4. Autoimmune disorders

Autoimmune diseases occur when the body mistakenly attacks its tissues and organs. Left shoulder pain can sometimes be a sign of an autoimmune disease in which the thyroid gland is attacked, causing hypothyroidism.

This can also be caused by an autoimmune disorder called inflammatory arthritis. This can affect people at any age and usually starts with joint pain followed by swelling and stiffness.

Left shoulder pain can also be caused by an autoimmune disorder affecting the kidneys called lupus erythematosus. This disorder can affect people of any age and may cause joint pain, long-term fatigue, and kidney problems.

The pain caused by autoimmune disorders is usually described as a deep, achy pain that moves across the upper back and down the left shoulder. It may be accompanied by joint swelling and joint stiffness.

5. Gas

Gas can collect in the digestive system and be released through belching or flatulence. Left shoulder pain can be caused by burping or flatulence that travels up and out of the digestive system through the chest. The pain caused by gas is described as a sharp, stabbing pain in the left armpit that can radiate down the arm.

You may also experience a burning sensation in the armpit if gas is trapped under the skin’s surface. Left shoulder pain caused by gas is often triggered after eating or drinking something that causes excess gas in the digestive system, such as beans, broccoli, or carbonated drinks.

6. IBS

Left shoulder pain can be a symptom of irritable bowel syndrome, a digestive disorder that causes abdominal pain, bloating, and changes in bowel movements. The pain caused by IBS usually occurs in the lower abdomen, but it can occasionally extend up into the left armpit and side of the upper arm.

Left shoulder pain caused by IBS is a deep, achy pain that can move around the torso and armpit. You may also experience cramping and abnormal bowel movements.

These symptoms can vary from person to person. Shoulder pain caused by IBS is often triggered after eating foods high in fiber, such as beans, oats, and broccoli. Stress and anxiety can also increase the risk of developing IBS.

7. Arthritis

Arthritis is one of the leading causes of shoulder pain. Osteoarthritis and rheumatoid arthritis are the most common types of arthritis that can affect the shoulder.

Rheumatoid arthritis occurs when the immune system is over-activated, and antibodies attack the lining of joints. This causes pain, swelling, and stiffness in the joints.

Rheumatoid arthritis can be treated with pain relievers, anti-inflammatory drugs, and immunosuppressants such as methotrexate.

8. Bursitis

The smooth, round swellings in joints such as the armpit area are called bursae. These help the joints to move more efficiently and reduce friction between the bones and tissues.

Bursitis occurs when bursae become inflamed due to repetitive motion, an injury, or a medical condition such as diabetes.

Bursitis can be treated with rest, ice packs, anti-inflammatory drugs, and a physical therapy program.

9. Tumors

Tumors such as cysts, abscesses, or infections in the armpit can cause severe pain. Tumors can cause shoulder pain in a variety of ways. Some shoulder tumors may press on the nerves or grow into other structures in the shoulder, like the muscles or tendons.

Some shoulder tumors can put pressure on the blood vessels in the shoulder, causing clots to form, which can block blood flow and cause necrosis (death) of the muscle tissue. There are several treatment options available for shoulder pain from a tumor, including surgery, medications, and physical therapy.

10. Injury

Injuries to the shoulder are common and happen to people of all ages. They can result from a fall, a car accident, a sports injury, or a work-related accident. Sometimes, the cause of the injury cannot be determined.

Most shoulder injuries are minor and can be treated at home. In some cases, however, shoulder injuries can be serious and may require surgery. If you have been diagnosed with a shoulder injury, you can take steps to help speed up your recovery.

Left shoulder pain treatment

  • Finding a qualified acupuncturist. Acupuncture is a very effective form of treatment that can help to relieve pain and normalize your body’s energy flow.
  • Taking some time off from work, if possible, to rest and recuperate. Your health is the most important thing, so don’t feel guilty about taking some time to heal.
  • Get plenty of rest and avoid any activities or movements aggravating your symptoms.
  • Using ice packs frequently on the painful area, as this can help to reduce inflammation and pain.
  • Taking supplements such as fish oil and probiotics can aid in inflammation resolution and healing processes within the body.

Diagnosis of left shoulder pain

The doctor will do a physical examination and ask about your symptoms and medical history. The doctor may suggest the following diagnostic tests to rule out other conditions.

  • Complete blood count (CBC) and blood chemistry tests: These tests check the levels of different substances in the blood.
  • Complete blood count with differential: This test measures the levels of different types of blood cells in the blood.
  • Urinalysis: This test checks the appearance of urine and the smell of urine.
  • Arthritis-specific blood test: This test detects antibodies in people with rheumatoid arthritis.
  • X-ray: An X-ray is a painless test that uses small amounts of radiation to make pictures of bones inside the body.
  • CT scan or MRI: These scans use small amounts of radiation to make pictures of organs and tissues inside the body.
  • Ultrasound: This test uses sound waves to make pictures of organs inside the body.

When to see a doctor?

Left shoulder pain can have many different causes and require other treatments, so getting a diagnosis as soon as possible is essential.

If the pain worsens or does not improve with rest and pain medication, you should see a doctor. This pain can sometimes signify something more serious, such as an injury or a severe health condition. It is essential to visit a doctor and check out.

Doctors often examine the left shoulder area to diagnose the pain. This may involve pressing on the left side of the chest or armpit to see if the pain spreads to the left shoulder. You may also be asked about your symptoms and medical history and given a blood test or other diagnostic tests.


Many different conditions can cause left shoulder pain. Knowing the cause of your pain is essential so you can receive the proper treatment. If you have armpit pain, the first thing to do is to see your doctor and diagnose it. The doctor will then prescribe the treatment based on the cause of the pain.

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