What is an intramuscular injection?

• A. Intramuscular injection
• B. Intravenous injection
• C. Subcutaneous injection
• D. Oral administration

Answer: (A)

An intramuscular injection is delivering medication directly into a muscle with a needle and syringe. The muscle’s rich blood supply allows the drug to be absorbed into the bloodstream fairly quickly—faster than injections into fatty tissue under the skin, but not as fast as delivering it straight into a vein. This route can accommodate larger volumes and is commonly used for vaccines and certain medications. In practice, the needle is inserted into a muscle such as the deltoid in the upper arm, the gluteal muscles, or the vastus lateralis in the thigh, typically at about a 90-degree angle, and the medication is injected then absorbed from the muscle into the circulation. This method is distinct from intravenous administration (into a vein), subcutaneous administration (into the fatty underlayer under the skin with slower absorption), and oral administration (taken by mouth and absorbed through the digestive system).