Intramuscular (IM) Injection Technique

Intramuscular injection delivers medication into the body of a skeletal muscle, where rich blood supply provides faster and more complete absorption than subcutaneous. SITE SELECTION: (1) Deltoid — lateral aspect of upper arm, 2-3 finger widths below acromion process. Max volume: 1-2mL. Most accessible for self-injection. (2) Ventrogluteal — preferred for larger volumes. Patient lies on side; place heel of hand on greater trochanter, point index finger to anterior superior iliac spine, spread middle finger posteriorly — inject in the triangle formed. Max volume: 3-5mL. (3) Vastus lateralis — outer middle third of thigh. Easy for self-injection. Max volume: 2-3mL. (4) Dorsogluteal — upper outer quadrant of buttock. Risk of sciatic nerve injury; least preferred. TECHNIQUE: Clean site with alcohol. For deltoid/VL: 90-degree angle with 1-inch needle (25G). For gluteal: 1.5-inch needle (22-23G) at 90 degrees. Aspirate briefly (pull back plunger for 5-10 seconds) — if blood appears, withdraw and try a new site. Inject slowly (10 seconds per mL). Z-TRACK METHOD: For medications that stain or irritate tissue, pull skin laterally before inserting needle, inject, wait 10 seconds, then release skin. This creates a zigzag path that prevents medication from tracking back to the surface.