This document provides information about intramuscular injections. It begins by defining an intramuscular injection as injecting medication into deep muscle tissue using a long needle. Medication is absorbed intermediately through the large blood supply in muscle tissue. Common sites for injections include the ventrogluteal, vastus lateralis, rectus femoris, and deltoid muscles. The procedure, required supplies, and potential complications are also outlined. Complications can include fibrosis, nerve damage, abscess, infection, and allergic reaction.