Pain in the upper right side of the chest may be due to trauma, pneumothorax, pleurisy, lung cancer, intercostal neuralgia, and pulmonary embolism. 1. Traumatic injury: the right upper chest skin abrasion, burn injury, etc. lead to skin breakage, or violent impact, extrusion, etc. lead to chest wall muscles, ribs and even thoracic cavity organs damage and pain. 2. Pneumothorax: because of the rupture of the right lung surface or the breakage of the right chest wall, which leads to the entry of external gas into the pleural cavity, increasing the pressure of the pleural cavity and causing pain in the upper right side of the chest. 3. Pleurisy: Infection, autoimmune and other factors lead to pleural inflammatory exudation, bleeding, adhesion and other lesions, which cause localized pain when involving the pleura of the right upper part of the chest. 4. Lung cancer: middle and late stage lung cancer invades into pleura and chest wall, stimulating rich nerve tissues of chest wall and causing pain in the upper right side of chest. 5. Intercostal neuralgia: pain in the upper right side of chest may be caused by localized intercostal neuropathy, which manifests as radiating stabbing pain distributed along the intercostal space. 6. Pulmonary embolism: ischemic infarction of lung tissue caused by pulmonary artery thrombus blockage, causing pain in the upper right side of the chest. The pain in the upper right side of the chest may be related to a variety of factors, and it is recommended to consult a doctor for a clear diagnosis.