Intramuscular (IM) injection is a parenteral route where medication is delivered deep into muscle tissue. Muscle tissue has a rich blood supply, allowing medications to absorb faster than subcutaneous injections. Nurses use this route for viscous solutions, oil-based suspensions, and drugs that irritate subcutaneous tissue. Onset of action typically ranges from 15 to 30 minutes, bypassing the digestive tract entirely.
Selecting the correct anatomical site prevents injury to major nerves, bones, and blood vessels.
Choosing proper equipment ensures medication reaches the muscle layer without hitting subcutaneous fat or bone. Needle length typically ranges from 1 to 1.5 inches for adults, while gauge size depends on medication viscosity—usually 20 to 25 gauge. Syringe capacity must match the prescribed volume, keeping in mind site limits. Accurate dosage calculation prevents toxicity or therapeutic failure.
Proper positioning relaxes the targeted muscle and reduces patient anxiety. For ventrogluteal injections, place the patient in a side-lying position with the top leg flexed. For vastus lateralis, have the patient lie flat on their back or sit up. Assess the skin integrity at the site for bruising, inflammation, or lumps before proceeding.
The Z-track technique seals the medication deep inside the muscle, preventing leakage into subcutaneous tissues. Pull the skin and subcutaneous tissue laterally about 1 to 1.5 inches before inserting the needle. Hold the tissue taut, inject the medication slowly, wait 10 seconds, withdraw the needle, and then release the skin.
Complications include sterile abscesses, nerve injury, hematoma formation, and accidental intravenous injection. Avoid nerves and blood vessels by using reliable anatomical landmarks. Never recap needles using two hands to prevent needlestick injuries. Dispose of all sharps immediately in a rigid safety box.
Document the medication name, dose, route, exact site, date, and time immediately after administration. Record the patient's immediate response and any adverse reactions. Return to check the injection site within 30 minutes to evaluate for local swelling, bleeding, or pain.