Which type of injection requires a 90-degree angle for administration?

An intramuscular injection requires a 90-degree angle for administration because this angle allows the needle to penetrate deeply into the muscle tissue. This type of injection is typically administered in larger muscles, such as the deltoid in the arm or the vastus lateralis in the thigh, where a significant volume of medication can be delivered directly into the muscle for rapid absorption.

Using a 90-degree angle helps ensure that the medication is deposited in the muscle rather than subcutaneously, which could happen with a shallower angle. This technique is crucial for effective medication delivery, especially for vaccines or other medications that are formulated to be absorbed quickly into the bloodstream from muscle tissue.

In contrast, subcutaneous injections are typically administered at a 45 to 90-degree angle, depending on the patient's body fat composition, to ensure the medication is deposited in the fatty tissue beneath the skin. Intradermal injections are given at a much shallower angle, often around 10 to 15 degrees, just beneath the epidermis. Intravenous injections are made directly into the bloodstream, which involves a different technique altogether and usually does not involve a standard angle since the goal is to access a vein directly.