Pain on the right side of the chest may be caused by costochondritis, pleurisy, pneumonia, pneumothorax and other reasons. 1. Costochondritis: Costochondritis is a common aseptic inflammation, usually caused by strenuous exercise, mild trauma and other factors. Costochondritis causes damage to the costal cartilage and ribs, resulting in pain on the right side of the chest. 2. Pleurisy: It is an inflammation of the pleura caused by infection of the pleura by pathogens such as viruses or bacteria, and irritation of the pleura by pathogens or metabolites. Patients with pleurisy may present with pain on the right side of the chest, cough, chest tightness and other symptoms. 3. Pneumonia: Pneumonia refers to the inflammation of the terminal airways, alveoli and interstitium of the lungs, which is mostly caused by pathogenic microorganisms, but may also be caused by other factors such as impaired immunity, allergies and drugs. Its clinical symptoms include pain on the right side of the chest, cough, sputum and so on. 4. Pneumothorax: mainly related to trauma, underlying lung diseases such as emphysema, chronic obstructive pulmonary disease, etc. Air enters the pleural cavity through the pleural rupture, which manifests as sudden chest pain, followed by chest tightness, dyspnea, accompanied by irritating dry cough. If the patient has the phenomenon of pain on the right side of the chest, it is necessary to go to the hospital in time for examination, identify the cause of the disease, and then standardize the treatment under the guidance of the doctor.