Sudden shoulder pain can occur with an injury, but it can also appear for other reasons, including arthritis, bursitis, and pneumonia.

Sudden shoulder pain without an injury can result from an underlying issue that the person may not previously have noticed. The condition may have progressed slowly up to the point when a person first feels pain.

Here, learn about 12 possible causes of sudden shoulder pain without an injury.

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Osteoarthritis (OA) is sometimes called wear-and-tear or bone-on-bone arthritis. It develops over time as the cartilage of the shoulder joint wears away. The bones start to rub together, causing friction and pain.

OA can also stem from an injury, such as a shoulder dislocation or fracture.

There may be no symptoms in the early stages, but pain can appear as OA progresses. It may become harder to move the shoulder. There may also be a crackling sound or feeling known as crepitus (popping joints).

OA can affect either or both joints in the shoulder: the acromioclavicular (AC) joint and the glenohumeral joint.

AC joint pain

OA in the shoulder most commonly leads to AC joint pain. This is the joint between the clavicle, or shoulder bone, and part of the shoulder blade known as the acromion.

AC joint pain mainly affects the top of the shoulder but may radiate to the side of the neck.

Glenohumeral joint pain

The glenohumeral joint is where the arm bone (humerus) joins the shoulder blade (scapula).

Glenohumeral joint pain is a symptom of OA. It will mainly affect the side or back of the shoulder and may feel as if it is deep in the joint. It may worsen with weather changes.

Why is my shoulder blade hurting?

Rheumatoid arthritis (RA) is an inflammatory condition that causes joint swelling and pain. It is an autoimmune disease and occurs when the immune system attacks healthy tissue.

RA in the shoulder can cause pain throughout the shoulder and will likely affect both shoulders. There may also be skin discoloration, warmth, and swelling.

The rotator cuff is a group of muscles and tendons that hold the shoulder joint in place.

Rotator cuff tendonitis refers to inflammation of these tendons, possibly due to damage or irritation. It can result from an injury but may also stem from repetitive shoulder movements. Genetic factors and older age may also contribute.

Tendonitis can cause pain and swelling throughout the shoulder and difficulty moving the arm. Pain may be worse at night.

Symptoms tend to worsen over time. It can lead to a torn or damaged tendon.

Rotator cuff — or subacromial bursitis — is an inflammatory condition that causes localized pain toward the front and side of the shoulder. The skin may also feel warm. The pain does not tend to radiate.

Bursitis results from inflammation and swelling of the bursa, a sac of fluid that helps cushion the joint.

Rotator cuff bursitis often affects people who do repetitive overhead actions, such as painting ceilings.

A rotator cuff tear can result from an injury, but tendon damage and pain can also result from long-term inflammation. The muscles and tendons that link the bones to the shoulder joint may become fully or partially torn or detached.

A partly torn or damaged tendon may be unable to hold the humerus properly in place. This can lead to friction between the humerus and the shoulder joint or glenoid socket. Damage can affect the bones, leading to pain.

Some conditions can lead to a reduced blood supply to the shoulder bone or avascular necrosis (AVN). Bone cells cannot thrive without a regular blood supply. In time, this can cause the shoulder bones and joints to collapse, leading to severe pain.

Factors that increase the risk of AVN include steroid use, sickle cell disease, and a history of traumatic shoulder injury. Sometimes, however, there is no clear cause.

Calcific tendonitis is a common cause of shoulder pain. It happens when deposits of calcium phosphate crystals build up in the rotator cuff tendons.

Up to 20% of people have no symptoms. However, it can lead to:

  • pain
  • reduced motion
  • stiffness
  • tendon damage over time

Doctors do not know exactly why calcific tendonitis occurs, but there may be links with diabetes and gout.

Pinched or compressed nerves in other parts of the body, such as the shoulder, neck, and upper back, can also cause shoulder pain.

A pinched nerve in the shoulder may lead to:

  • pain
  • weakness in the shoulder and arm
  • numbness and tingling in the hands

Cervical radiculopathy refers to a compressed or irritated nerve in the upper back, known as the cervical spine. The nerve can become pinched as it branches out from the spine.

It can cause similar symptoms to a pinched nerve in the shoulder.

Cervical radiculopathy can result from an injury but can also happen as people get older due to the disks of the spine becoming dried out and compressed.

Thoracic outlet syndrome

Thoracic outlet syndrome (TOS) involves compression or pinching of the nerves and blood vessels in the shoulder, arm, and neck. Neurogenic TOS can result in a dull, aching pain in the shoulder, neck, and armpit. The area just above the collarbone may be tender.

Possible causes include:

  • tumors that press on a nerve
  • poor posture
  • changes in bone formation
  • repetitive arm movements

It is more common in females and may appear in pregnancy.

Commonly known as a frozen shoulder, adhesive capsulitis is an inflammatory condition that leads to:

It can result from an injury, but often there is no clear cause.

Risk factors may include:

Experts do not know exactly why it happens, but it may occur when inflammation in the shoulder leads to fibrosis and adhesions in the joint. The inflammation causes the pain, while the adhesions and fibrosis make the shoulder harder to move.

This type of pain is known as referred pain, as it affects the shoulder but does not relate directly to it.

Shoulder pain can also result indirectly from cardiac problems, such as:

Referred pain can also affect the shoulder due to:

Other underlying causes of shoulder pain can include:

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Anyone with new, severe, persistent, or worsening shoulder pain may seek medical advice. In some cases, early intervention can help prevent shoulder pain and complications from becoming worse.

If other symptoms are present, a person may need urgent medical attention. Shoulder pain accompanied by chest pain and breathing difficulty, for instance, can be a sign of a heart attack.

Is it a heart attack?

Heart attacks occur when there is a lack of blood supply to the heart. Symptoms include:

  • chest pain, pressure, or tightness
  • pain that may spread to arms, neck, jaw, or back
  • nausea and vomiting
  • sweaty or clammy skin
  • heartburn or indigestion
  • shortness of breath
  • coughing or wheezing
  • lightheadedness or dizziness
  • anxiety that can feel similar to a panic attack

If someone has these symptoms:

  1. Dial 911 or the number of the nearest emergency department.
  2. Stay with them until the emergency services arrive.

If a person stops breathing before emergency services arrive, perform manual chest compressions:

  1. Lock fingers together and place the base of hands in the center of the chest.
  2. Position shoulders over hands and lock elbows.
  3. Press hard and fast, at a rate of 100–120 compressions per minute, to a depth of 2 inches.
  4. Continue these movements until the person starts to breathe or move.
  5. If needed, swap over with someone else without pausing compressions.

Use an automated external defibrillator (AED) available in many public places:

  1. An AED provides a shock that may restart the heart.
  2. Follow the instructions on the defibrillator or listen to the guided instructions.
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The treatment for shoulder pain will depend on the cause.

Options include:

Try these stretches for tight shoulders.

Here are some questions people often ask about shoulder pain.

How can I tell if shoulder pain is serious?

Anyone with new, severe, or worsening shoulder pain may consider contacting a doctor. If there are other symptoms, such as chest pain and difficulty breathing, seek urgent medical attention. This could be a sign of a heart attack.

Why does my shoulder hurt without an injury?

There are many reasons for shoulder pain without any injury. Often, these conditions worsen over time, and a person does not notice the pain in the early stages.

Possible causes include osteoarthritis and a frozen shoulder.

Shoulder pain may appear without an injury for many reasons, such as arthritis, bursitis, gallstones, pneumonia, and heart problems.

Anyone with concerns about shoulder pain may wish to seek medical advice. Early treatment may help prevent worsening symptoms and complications, such as a ruptured tendon.