Administering a non-intravenous injection requires precision and strict adherence to safety protocols to ensure effective medication delivery. The two most frequent types are subcutaneous (SubQ) and intramuscular (IM), which target different tissue layers using distinct techniques. While these instructions provide a framework for correct administration, they are not a substitute for formal, hands-on professional training.
Essential Supplies and Medication Preparation
Preparation begins by assembling necessary supplies on a clean surface to maintain sterility. Supplies include the medication vial or ampule, a sterile needle and syringe, an alcohol swab, and an FDA-cleared sharps container. Needle selection depends on the injection type. Subcutaneous injections require a short needle (3/8 to 5/8 inches) with a high gauge (25G to 30G) to reach the fatty layer.
Intramuscular injections require a longer needle (1 to 1.5 inches for adults) with a lower gauge (20G to 25G) to penetrate muscle tissue. Before drawing medication, clean the vial’s rubber stopper vigorously with an alcohol swab and allow it to air dry completely. To prepare the syringe, pull the plunger back to draw an amount of air equal to the prescribed dose.
Inject this air into the vial to prevent a vacuum, making it easier to withdraw the liquid medication. Invert the vial and slowly withdraw the correct dose into the syringe, keeping the needle tip submerged to avoid drawing air. If air bubbles are present, gently flick the barrel to encourage them to rise, then carefully expel them by pushing the plunger slightly. The syringe is now ready for administration; ensure the needle tip remains uncontaminated.
Identifying the Correct Injection Site
Site selection depends on the required tissue depth for absorption. Subcutaneous injections deliver medication into the adipose (fatty) tissue layer beneath the dermis. This tissue has fewer blood vessels than muscle, resulting in slower, more sustained absorption.
Suitable SubQ sites are areas where fat can be easily isolated, such as the back of the upper arm, the front and sides of the thighs, and the abdomen. When using the abdomen, avoid the two-inch area immediately surrounding the navel.
Intramuscular injections deliver medication deep into highly vascularized muscle tissue, allowing for faster systemic absorption. The site must be chosen carefully to avoid major nerves and blood vessels. The three most commonly used areas for adults are the deltoid, the vastus lateralis, and the ventrogluteal site.
Common Intramuscular Sites
The deltoid muscle in the upper arm is easily accessible but is generally limited to 1 milliliter (mL) or less. The injection site is located two to three finger-widths below the acromion process (the bony prominence at the shoulder).
The vastus lateralis muscle, located on the outer middle third of the thigh, is preferred for self-administration and for infants due to its large muscle mass. Identify the area by dividing the thigh from the hip bone (greater trochanter) to the knee into thirds, and using the middle third.
The ventrogluteal site is considered the safest for adults and children because it is free from major nerves and blood vessels. Locate this site by placing the heel of the hand on the greater trochanter, with the index finger on the anterior superior iliac spine. The middle finger points toward the iliac crest, forming a “V” shape where the injection is given in the center.
Step-by-Step Administration Technique
Before the injection, perform hand hygiene and don clean gloves. Cleanse the selected site with a new alcohol swab, moving outward from the center in a circular pattern. Allow the skin to air dry completely before proceeding.
Subcutaneous Technique
For a SubQ injection, gently gather or “pinch” the skin between the thumb and forefinger to elevate the fatty tissue away from the muscle. Insert the needle quickly at an angle determined by the amount of pinchable tissue: 45 degrees if only one inch can be grasped, or 90 degrees if two inches can be grasped. Once the needle is fully inserted, release the pinched skin and inject the medication slowly and steadily to minimize discomfort.
Intramuscular Technique
For an IM injection, use the Z-track technique, which seals the medication into the muscle tissue to prevent leakage into the subcutaneous layer. Use the non-dominant hand to pull the skin and subcutaneous tissue laterally or downward approximately one inch before insertion. The needle must be inserted at a mandatory 90-degree angle using a quick, dart-like motion.
After insertion, and before injecting irritating medications, brief aspiration may be required by pulling back slightly on the plunger for five to ten seconds to check for blood return. If blood enters the syringe, withdraw the needle, discard the syringe, and prepare a new injection for a different site. If no blood is returned, inject the medication slowly (about 10 seconds per 1 mL) to allow muscle fibers to accommodate the volume. Once empty, count to ten before smoothly withdrawing the needle while simultaneously releasing the skin, which locks the medication within the muscle.
Post-Injection Safety and Disposal
Immediately following the injection, follow safety protocols to prevent needlestick injuries. Engage the safety mechanism on the syringe, if present, and immediately dispose of the entire unit into a designated sharps container. The container must be puncture-proof, rigid, and clearly labeled with a biohazard warning.
Sharps containers must never be overfilled; seal and dispose of them when they are no more than three-quarters full, following local guidelines. After removing the needle, apply gentle pressure with clean gauze or a cotton ball to stem minor bleeding. Do not rub or massage the site, as this can push medication into the subcutaneous tissue, causing irritation or altering absorption. Finally, monitor the site for adverse reactions, such as excessive bleeding, swelling, pain, or allergic signs, and document the injection time, site, and observations.