Subcutaneous and Intramuscular Injection Technique

Objective. Students will prepare and administer a simulated subcutaneous and intramuscular injection using correct site selection, aseptic technique, and safe sharps disposal on a task trainer.

Administering injections safely and correctly is one of the most essential hands-on skills you will carry into every clinical setting as an LPN. This lesson covers the two most common parenteral routes you will use: subcutaneous (SubQ) and intramuscular (IM). Mastery requires attention to site selection, aseptic technique, needle selection, and sharps safety — each step directly protects your patient and yourself.

Subcutaneous Injections

Subcutaneous injections deliver medication into the fatty tissue layer just beneath the skin. This route is used for medications that require slow, steady absorption — insulin and certain anticoagulants are common examples.

Common SubQ sites: The outer aspect of the upper arm, the abdomen (avoiding a two-inch radius around the navel), the anterior thigh, and the upper back/scapular area. Rotate sites systematically to prevent lipodystrophy (fatty tissue changes caused by repeated injections in the same spot).

Needle selection for SubQ: Typically a 25–28 gauge, ½-inch needle is used for most adults. A 45-degree angle is used for thin patients; a 90-degree angle is appropriate when there is adequate subcutaneous tissue. Never aspirate before a SubQ injection unless your facility policy or a specific medication requires it — current evidence and standard practice no longer recommend routine aspiration for most SubQ medications.

Intramuscular Injections

Intramuscular injections deliver medication directly into muscle tissue, allowing faster absorption than the SubQ route. The IM route is used for vaccines, certain antibiotics, hormones, and other medications that require deeper delivery or rapid uptake.

The four IM sites you must know:

1. Ventrogluteal — Located on the lateral hip, this site targets the gluteus medius and minimus muscles. It is the preferred IM site for adults and children older than seven months. It is away from major nerves and blood vessels, making it the safest choice for most IM injections.

2. Vastus lateralis — Located on the anterolateral thigh. This is the preferred site for infants and toddlers under seven months and is also acceptable for adults. It is easy to locate and free of major nerves near the injection area.

3. Deltoid — Located on the lateral upper arm, two to three finger-widths below the acromion process. Used primarily for vaccines and small-volume injections (generally no more than 1 mL in adults). Avoid this site in patients with little muscle mass.

4. Dorsogluteal — Located in the upper outer quadrant of the buttock. This site is no longer preferred because of proximity to the sciatic nerve and the superior gluteal artery, increasing the risk of nerve injury or inadvertent vascular injection. Most professional guidelines recommend avoiding this site unless no other site is available.

Needle selection for IM: The gauge and length depend on the site and the patient's body habitus. A 22–25 gauge needle is typical; length ranges from 1 inch to 1.5 inches for most adult IM injections. A 90-degree angle is used for all IM injections.

The Z-Track Method

The Z-track technique is recommended for all IM injections. Pull the skin and subcutaneous tissue approximately one to two inches laterally away from the injection site, insert the needle at 90 degrees, inject the medication slowly, wait ten seconds, withdraw the needle, and release the skin. This seals the medication in the muscle, reducing irritation and leakage into subcutaneous tissue.

Aseptic Technique for Drawing Up Medication

Aseptic technique prevents contamination of the medication and the injection site.

Perform hand hygiene and don gloves.
Check the medication label against the medication administration record (MAR) — do this at least three times: when you pick up the vial, when you draw up the medication, and before administration.
Clean the rubber septum of the vial with an alcohol swab and allow it to dry.
Draw back the plunger to fill the syringe with air equal to the volume of medication you need, then insert the needle into the vial.
Inject the air, invert the vial, and withdraw the correct volume of medication.
After drawing up, change to a fresh needle of appropriate gauge and length before administration — this ensures a sharp, uncontaminated needle reaches the patient.
Clean the patient's skin with an alcohol swab using a circular outward motion and allow it to dry fully before injecting.

Safe Sharps Disposal

Needle-stick injuries are a significant occupational hazard. Follow these rules without exception:

Never recap a needle after use. Recapping is the leading cause of needle-stick injuries.
Dispose of the entire syringe and needle unit directly into the puncture-resistant sharps container immediately after withdrawal.
Never overfill a sharps container — replace it when it reaches the fill line.
If a needle-stick occurs, follow your facility's exposure control plan immediately.

Patient Safety and Documentation

Always explain the procedure to the patient before beginning. Confirm allergies and patient identity using two identifiers. Observe the site for several minutes after injection and document the medication, dose, route, site used, time, and patient response in the medical record promptly after administration.

Key terms8

Subcutaneous (SubQ) injectionAdministration of medication into the fatty tissue layer beneath the skin, allowing slow and steady absorption.

Intramuscular (IM) injectionAdministration of medication directly into muscle tissue, allowing faster absorption than the subcutaneous route.

Ventrogluteal siteThe preferred IM injection site for most adults and children over seven months, located on the lateral hip over the gluteus medius muscle, away from major nerves and vessels.

Z-track techniqueAn IM injection method in which skin and subcutaneous tissue are pulled laterally before needle insertion and released after withdrawal to seal medication within the muscle and reduce irritation.

Aseptic techniquePractices that prevent the introduction of microorganisms during medication preparation and administration, including hand hygiene, use of gloves, and cleaning injection surfaces.

LipodystrophyAbnormal changes in fatty tissue at injection sites caused by repeated injections in the same location; prevented by systematic site rotation.

Sharps containerA puncture-resistant, leak-proof container used for the immediate disposal of used needles and syringes to prevent needle-stick injuries.

Gauge (needle)A measurement of needle diameter; the higher the gauge number, the smaller (thinner) the needle bore.

In class: Identify and mark the four IM injection sites (ventrogluteal, vastus lateralis, deltoid, and dorsogluteal—noting dorsogluteal is no longer preferred) on an anatomical diagram, then locate each site on the injection task trainer. · Draw up a simulated injectable medication from a vial using aseptic technique, change to an appropriate gauge needle, administer IM to the task trainer, and dispose of the syringe in the sharps container without recapping. · Self-evaluate using a recorded video of their injection technique compared against the instructor-demonstrated model, listing two areas of improvement in their clinical log.
Materials: Injection task trainer arm, syringes (1 mL and 3 mL), needles (various gauges and lengths), simulated medication vials (saline), alcohol swabs, gloves, sharps container, anatomical diagram of injection sites, clinical log binder
Check: Instructor-scored injection technique checklist; critical steps (aseptic technique maintained, correct site, no recapping of needle) must be 100% correct; total checklist score 85% or higher.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.