Injections are among the most common health care procedures throughout the world, with at least 16 billion administered in developing and transitional countries each year. Intravenous (IV), subcutaneous (SC), and intramuscular (IM) are three most frequently used injection routes in medication administration. IV injection is the introduction of a medication into the veins using a needle, and it is used when rapid absorption is called for, when fluid cannot be taken by mouth, or when the medication to be administered is too irritating to be injected into the skin or muscles. SC injection is administered as a bolus into the subcutis. IM injection is the technique used to deliver a medication deep into the muscles, allowing the medication to be absorbed into the bloodstream quickly. Prescribing information for some medications notes that they can be injected via one or more routes (eg, epinephrine can be delivered by IV, IM, or SC route), while prescribing information for the majority of injectable medications only describes one injection route.