After injection, the medicine first reaches the right atrium of the heart. Injections are usually injected into the distal vein, the liquid follows the venous blood circulation first back to the right atrium, through the right atrium to the right ventricle, from the right ventricle and then flow through the pulmonary artery, pulmonary capillaries, pulmonary veins, from the pulmonary veins and then back to the heart of the left atrium, and then through the left atrium to reach the left ventricle, through the left ventricle of the liquid and then to the systemic arterial blood. Injection may lead to redness, swelling, hardness, infection, muscle contracture, vasculitis and other side effects at the injection site. If any discomfort occurs after the injection, you should consult a doctor for standardized treatment under the doctor’s guidance, and go to a standardized medical institution for the injection.