The pain in the right side of chest when breathing hard may be caused by pneumothorax, pleurisy, costochondritis and other factors, which should be treated with medication or surgery in time. 1. Pneumothorax: if the right side of the chest is traumatized or the lungs are diseased, the symptom of pain when breathing hard on the right side of the chest may occur, at this time, you should pay attention to bed rest, and if necessary, you should be given oxygen therapy, or pumping therapy, etc. If the conservative treatment is ineffective, you may need to carry out surgery such as open-heart surgery and other surgical treatments. 2. Pleurisy: If the pleura is infected by bacteria, viruses and other pathogenic bacteria, it may lead to the symptom of pain in the right side of the chest. At this time, you can use antibiotics such as cefaclor to treat conjunctivitis caused by bacterial infections, acyclovir to treat viral infections or isoniazid and other medicines to treat tuberculous pleurisy and so on. 3. Rib chondritis: If inflammation occurs in the cartilage at the junction of the right sternum and ribs, the symptom of right-sided chest pain may appear, you can use drugs such as ibuprofen and acetaminophen to reduce the inflammatory reaction, and if necessary, you can surgically remove the rib cartilage to completely remove the lesion and prevent the disease from further development. If the right side of the chest hurts when you breathe hard, you should consult the doctor in time, complete the relevant examinations, and follow the doctor’s instructions to choose the appropriate treatment, so as not to delay the condition and cause adverse consequences.