The difference between subcutaneous injection and intramuscular injection is that the injection site is different and the absorption speed is different. 1. Intramuscular injection: Intramuscular injection needs to be injected in the muscle layer, which is rich in blood vessels and absorbs faster. Intramuscular injection is usually used for antiviral serum treatment. Because of the rich blood supply around the muscle, it can spread to the lesion quickly to achieve the therapeutic effect, while the angle of intramuscular injection is 90 degrees. However, if intramuscular injection is performed in the biceps muscle, it is recommended that the tip of the needle be injected intramuscularly at an angle of 30-45 degrees to the skin. The muscle is rich in peripheral nerves, so attention should be paid to positioning when injecting drugs. 2. Subcutaneous injection: Subcutaneous injection needs to be injected into the subcutaneous fat layer, which is slower to be absorbed. Usually it can be used for insulin injection, leprosy vaccine injection, influenza vaccine, etc. The angle of injection is usually around 30 degrees to 45 degrees, and attention should be paid to the positioning and aseptic technical operation when injecting. Different drugs require different injection methods and approaches, so it is recommended to always be under the guidance of a doctor to avoid delaying the disease and affecting your health.