IM injections, also known as intramuscular injections, are a method of administering vitamins into the muscles. They are commonly used to deliver vaccines, hormones, and other vitamins that cannot be taken orally or need to be delivered quickly and directly into the bloodstream. The vitamins is usually injected into the muscle using a needle and syringe, and the muscle tissue helps to absorb the vitamins and release it into the bloodstream. Common sites for IM injections include the deltoid muscle in the arm, the gluteal muscle in the buttocks, and the thigh muscle.