Intramuscular injections are given primarily in three locations: the vastus lateralis muscle found in the thigh, the deltoid muscle found in the shoulder and the ventrogluteal or dorsogluteal muscles found in the buttock, according to Healthline. Intramuscular injections are used by medical practitioners to provide vaccines and drugs.
Intramuscular injections are used in cases where other medicine delivery methods are either unsuitable or ineffective. These can include oral ingestion, intravenous injection (into the blood via a vein) and subcutaneous (where the medicine is injected into the epidermis of the patient just under the surface). Intramuscular is accepted as the fasted method of injection, states Healthline.