What are the four types of injections that are given?

The four main types of injections are intramuscular (IM), subcutaneous (SC or SQ), intravenous (IV), and intradermal (ID). Intramuscular injections deliver medication deep into the muscle, subcutaneous injections administer it into the fatty tissue just under the skin, intravenous injections provide immediate effects by delivering drugs directly into the bloodstream, and intradermal injections are given into the dermis layer of the skin, often for allergy tests or vaccinations. Each type is used based on the medication's properties and the desired speed of absorption.