If you have shoulder pain when you breathe, it may be related to the following reasons: 1. There may be a serious trauma to the shoulder joint. If the patient has a fracture of the clavicle, dislocation of the acromion, fracture of the scapula or a serious rib fracture, this may pull on the shoulder joint when breathing and cause pain in the shoulder joint. 2. There may be some serious internal lesions in the chest cavity. For example, if the patient has severe tuberculosis, severe pneumonia, pneumothorax, or hemothorax, it may cause pain around the tip of the lung during breathing. This may cause the patient to believe that there is pain in the shoulder joint on this side. 3. There may be some peripheral nerve lesions. This is often seen in patients with neurogenic cervical spondylosis or thoracic outlet syndrome, which may cause the nerve to be squeezed more severely during breathing, resulting in radiating pain in the affected shoulder joint and upper extremity.