Rotator Cuff Tendinitis: This condition is the most common cause of shoulder pain, especially when lifting the arm. It involves inflammation of the tendons surrounding the shoulder joint, leading to pain and limited mobility.

Adhesive Capsulitis (Frozen Shoulder): Characterized by stiffness and pain in the shoulder joint, adhesive capsulitis can cause significant discomfort when lifting the arm. It often results from inflammation and scarring of the tissues surrounding the shoulder joint.
Bursitis: Inflammation of the bursae, fluid-filled sacs that cushion bones, tendons, and muscles near joints, can cause pain when lifting the arm. Shoulder bursitis is a common condition that can be caused by repetitive motion or direct trauma.
Labral Tears: Tears in the labrum, a cartilage structure surrounding the socket of the shoulder joint, can cause pain and discomfort, especially when lifting the arm. These tears can result from acute injury or chronic wear and tear.

Fracture: Although less common, a fracture in the shoulder region (e.g., humerus, scapula, or clavicle) can cause severe pain when lifting the arm. Missing a fracture diagnosis can lead to improper healing and long-term disability.
Axillary Artery Aneurysm or Thoracic Outlet Syndrome: These vascular conditions can cause shoulder pain due to compression or damage to the blood vessels or nerves. They are less common but critical to diagnose to prevent serious complications like limb ischemia or permanent nerve damage.
Referred Pain from Cardiac or Pulmonary Issues: In some cases, shoulder pain can be referred from cardiac (e.g., myocardial infarction) or pulmonary (e.g., pneumonia, pulmonary embolism) conditions. These are medical emergencies that require immediate attention.

Osteonecrosis of the Humeral Head: A condition where the blood supply to the humeral head is interrupted, leading to bone death and potentially causing shoulder pain when lifting the arm. It is less common and often associated with specific risk factors like long-term steroid use or severe trauma.
Tumors: Both benign and malignant tumors can cause shoulder pain, although they are rare causes of pain when lifting the arm. Early diagnosis is crucial for effective treatment and prognosis.
Infection (Septic Arthritis or Osteomyelitis): Infections within the shoulder joint or bone can cause severe pain, especially with movement. These conditions are medical emergencies requiring prompt antibiotic treatment and possibly surgical intervention.