A subcutaneous injection delivers medication into the fatty tissue layer just beneath the skin. This method is used for medications that require slow, sustained absorption into the bloodstream. Common medications administered this way include insulin, certain vaccines, and blood thinners like heparin. Subcutaneous injections are less painful than intramuscular injections because they use smaller, shorter needles and do not penetrate deep into muscle tissue. This guide explains how to safely administer a subcutaneous injection in the arm.
Gathering Supplies and Preparing
Gather all necessary supplies. You will need the prescribed medication, a sterile syringe with an attached needle, alcohol wipes, cotton balls or gauze, and a puncture-resistant sharps container for disposal. If the medication is stored in the refrigerator, allow it to reach room temperature for about 30 minutes before injection to minimize discomfort.
Wash your hands thoroughly with soap and water for at least 15-20 seconds to prevent infection, then dry them with a clean towel. If using an alcohol-based hand sanitizer, ensure it contains 60-90% alcohol and rub your hands until dry.
After handwashing, prepare the medication by checking the label for the correct type, dose, and expiration date. If drawing medication from a vial, clean the rubber stopper with an alcohol wipe and allow it to dry. Pull the plunger back to draw air into the syringe equal to the medication dose, then insert the needle into the vial and inject the air before withdrawing the medication.
Choosing the Right Spot on the Arm
Selecting the appropriate injection site is important for effective medication absorption and patient comfort. The outer back area of the upper arm is chosen for subcutaneous injections due to its accessible layer of fatty tissue. This area has fewer major blood vessels and nerves compared to other parts of the arm, reducing the risk of complications.
To identify the correct spot, locate the area about three inches above the elbow and three inches below the shoulder on the upper arm. If self-injecting, folding one arm across the chest can make the back of the arm more accessible. Pinch up enough fatty tissue to ensure the injection enters the subcutaneous layer and not the muscle. For individuals receiving multiple injections, rotating injection sites is important to prevent tissue damage, such as fatty lumps, which can interfere with medication absorption. Each new injection should be at least one inch away from the previous site.
Step-by-Step Injection Technique
Clean the injection area with an alcohol wipe. Starting from the center, use a firm, circular motion to clean outward, covering an area approximately two inches in diameter. Allow the alcohol to air dry completely (about 20-30 seconds) to prevent stinging during the injection and allow disinfection. Do not fan or blow on the area.
With the non-dominant hand, gently pinch a fold of skin and fatty tissue. This helps separate the fatty tissue from the underlying muscle, ensuring the medication is delivered into the correct layer. Hold the syringe in your dominant hand like a pencil or a dart. Remove the needle cap by pulling it straight off, being careful not to contaminate the needle.
Insert the entire needle quickly and firmly into the pinched skin. The angle of insertion depends on the amount of fatty tissue present. For most individuals, a 90-degree (straight down) angle is appropriate to ensure the medication reaches the fatty tissue. If there is very little subcutaneous fat, a 45-degree angle may be used. Once the needle is fully inserted, release the pinched skin.
Slowly and steadily push the plunger down to inject the entire amount of medication. Injecting too quickly can cause discomfort or bruising. After the medication has been fully administered, wait approximately 10 seconds before withdrawing the needle. This pause allows the medication to disperse into the tissue and helps prevent leakage. Finally, withdraw the needle quickly at the same angle it was inserted.
After the Injection
After removing the needle, place a clean cotton ball or gauze over the injection site and apply light pressure for several seconds. Avoid rubbing the site, especially if injecting certain medications like heparin, as this can increase bruising or discomfort. A small amount of bleeding or a clear fluid may appear at the site. If needed, a bandage can be applied.
Proper disposal of the used needle and syringe is important for safety. Never recap a used needle, as this increases the risk of accidental needle sticks. Immediately place the entire syringe and needle into a puncture-resistant sharps container. These containers should be labeled to warn of hazardous waste. When the container is about three-quarters full, it should be sealed and disposed of according to local regulations.
Monitor the injection site for any signs of adverse reactions following the injection. Common, mild reactions can include temporary pain, redness, swelling, or itching at the site. However, if you experience increasing pain, spreading redness, warmth, pus, fever, or severe allergic reaction symptoms such as trouble breathing or facial swelling, seek prompt medical attention.