12.5: Administering Subcutaneous Injections

Learning Objectives

By the end of this section, you will be able to:

• Describe the guidelines for using the subcutaneous (SQ) route for medication administration
• Identify common medications administered using SQ injections
• Demonstrate the steps for correct administration of SQ injections

Parenteral medications injected into the adipose tissue between the skin and muscle are known as subcutaneous (SQ) injections. Certain medications are indicated for this route because absorption is slow within adipose tissue. The nurse must be able to accurately perform the steps for administration, including selecting an appropriate injection site and needle size, and using proper technique. This section will provide you with the knowledge to safely administer medications via the SQ route.

Guidelines for Using the SQ Route

Medications administered via the SQ route are injected beneath the skin into the adipose tissue, just below the epidermis and dermis. Medications administered via this route have a slow, sustained rate of absorption because there are fewer blood vessels present to distribute the medication. Physical exercise and the application of hot or cold compresses alters the blood flow to the tissues, which may alter the rate of medication absorption. Usually, no more than 1 mL of medication will be injected at any given time via the SQ route because larger amounts of medication may cause discomfort to the patient and may not be absorbed appropriately. To ensure that the medication is injected into the adipose tissue, careful consideration must be given when selecting an appropriate anatomical site for the SQ injection.

Anatomical Sites for SQ Injections

When administering medications via the SQ route, it is important to select an appropriate anatomical site. The most commonly used sites include the outer portion of the upper arm, the anterior thigh, the abdomen below the costal margin to the iliac crest no closer to the umbilicus than 1 in (2.5 cm), the upper ventral gluteal region, and the upper back. (Figure 12.30). The site selected should be free of skin lesions, rashes, and moles. Avoid sites that are bruised, tender, hard, swollen, or over bony prominences. When administering SQ injections, the site should be rotated to prevent lipoatrophy or the formation of lipohypertrophy of the skin.

Figure 12.30: This illustration shows the anatomical sites appropriate for administering SQ injections. The upper back is another appropriate SQ injection site. (CC BY 4.0; Rice University & OpenStax)

Common Medications Given Subcutaneously

Subcutaneous administration may be used to administer a variety of medications because of its high bioavailability and rapid onset of action. Medications administered subcutaneously are given in small amounts, typically 1 mL or less. Examples of medications that may be administered via the SQ route include narcotics, antiemetics, heparin, fertility medications, and insulin.

Narcotics

Pain is a very common symptom in patients with advanced cancer. One means to assist with pain control for this population is with SQ injections of narcotics. Due to the slower rate of absorption, intermittent SQ injections of narcotics may be added to the pain relief regime to offer better pain control. Most opioids, such as morphine, fentanyl, and tramadol, can be administered subcutaneously. Often, these medications will be delivered to the patient via an indwelling subcutaneous needle attached to a portable injector device that can be set to deliver a certain amount of the medication at given intervals.

Antiemetics

Antiemetics, such as metoclopramide (Reglan) or dexamethasone (Decadron), may be administered subcutaneously. This route may be the preferred route when the patient is vomiting, oral absorption is in doubt, or there is no IV access. Subcutaneous antiemetics are often used for patients with advanced cancer and those under palliative care.

Heparin

Heparin is a high-alert medication used to reduce the risk of blood clot formation. Heparin may be supplied in vials or prefilled syringes. The syringes usually come in an identifiable color with tiny numbering specific for heparin dosing. If heparin is supplied in a vial, always use an official heparin syringe to withdraw the medication. There are multiple concentrations of heparin, which substantially increases the risk to the patient of a medication error. To help prevent a wrong dose or wrong concentration error, two nurses are required to double-check the medication before administration. The nurse should review laboratory results, such as partial thromboplastic time (PTT) and activated partial thromboplastin time (aPTT) that characterize blood coagulation, before administering heparin to ensure the correct dose of the medication is administered to the patient. Risks associated with heparin include bleeding, hematuria, hematemesis, bleeding gums, and melena (dark, tarry stools indicative of gastrointestinal bleeding). Heparin sites should be rotated because of the risk of changes in skin appearance and texture. Typically, the abdominal area, at least 2 in (5 cm) away from the umbilicus, is preferred because this site results in the least amount of bruising and pain for the patient. Heparin should be injected at a 90-degree angle and administered over a thirty-second period to allow time for the subcutaneous tissue to accommodate the injected volume. Injecting heparin slowly reduces pressure to the site, capillary bleeding, and site pain. Do not massage the injection site after administering heparin because this may create a hematoma.

When administering heparin, it is also important to assess the patient’s medical conditions and medications before administration. Due to the risk of bleeding, heparin should not be given when the patient is at an increased risk of hemorrhage. For example, heparin would be contraindicated for individuals experiencing severe trauma, a cerebral vascular accident, or recent childbirth. The nurse would also want to assess over-the-counter or herbal medications that may interact with heparin (e.g., aspirin, garlic, ginger, nonsteroidal anti-inflammatory drugs [NSAIDs]) or other prescription medications that may interact with heparin (e.g., thrombolytics and lisinopril).

Clinical Safety and Procedures (QSEN): QSEN Competency: Types of Heparin Preparations

Heparin is a medication commonly used to prevent blood clot formation. It comes in various forms for different medical purposes, including subcutaneous (SQ) injections, heparin locks, and heparin flushes.

• Heparin SQ injection: Subcutaneous injections of heparin are often used for prophylaxis against deep vein thrombosis (DVT) or to prevent blood clots in certain medical conditions.
• Heparin lock (Heparin lock flush): A heparin lock involves placing a small amount of heparin solution into an intravenous (IV) catheter when it is not actively in use to keep the IV line open and help prevent clot formation.
• Heparin flush: A heparin flush is similar to a heparin lock but involves using a small amount of heparin solution to flush IV lines after medication administration to ensure the medication is fully delivered and blood clots do not form in the IV line.

Fertility Medications

Fertility medications (e.g., leuprolide [Lupron], chorionic gonadotropin [Ovidrel], menotropin [Menopur], and follicle-stimulating hormone [Gonal-F]) may be administered subcutaneously to stimulate multiple egg development. Typically, they are injected into the stomach, at least 1 in (2.5 cm) away from the umbilicus, or the top of the thighs; however, they may also be administered in the adipose tissue found in the back of the arm. Rotating the site with each injection will help to reduce pain and discomfort. Typically, these medications are self-administered; therefore, it is important for the nurse to teach the patient how to safely administer the medication, cleanse the site with an alcohol swab before administering the medication, and dispose of the used needles and syringes. Education may also require helping the patient to overcome their fear of injections by using ice for fifteen to thirty seconds before administration to numb the site and experimenting with various sites to locate the least-sensitive areas.

Insulin

Insulin is one of the most commonly administered subcutaneous medications. It is considered a high-risk medication; therefore, special care must be taken to ensure the patient’s safety, including having two nurses double-check the insulin type and dosage with the medication administration record while drawing up the medication and again before administration. Insulin must be administered using an insulin syringe. Insulin syringes come in 30-, 50-, and 100-unit measurements, which are carefully calibrated to ensure accuracy. If administering more than one type of insulin, consideration should be given regarding whether the insulins can be mixed and adhering to proper procedures for mixing insulins (see Mixing Insulins).

Insulin should be stored in the refrigerator until it is ready to be used. After the vial is opened, it may then be stored at room temperature according to the agency’s policy. If the vial is cold, allow the insulin to come to room temperature before administering the medication. The insulin vial should always be inspected before use to ensure the insulin administered is the type of insulin prescribed. The vial should not be expired and any abnormalities in the insulin solution should be noted. For example, if the solution is frosted, discolored, has clumps, or is cloudy (and is supposed to be clear), then return the vial to the pharmacy and retrieve a new vial.

When administering insulin, the timing of the administration is critical. Short- or rapid-acting medications should be administered within fifteen minutes of the mealtime. Intermediate-acting insulins may be taken with breakfast and dinner, and long-acting insulins may be given at bedtime. Knowing the peak action and duration of insulin is critical before administration. In addition, blood sugar levels should be tested regularly and the results assessed before administering insulin, according to the agency’s policy.

Insulin absorption rates vary depending on the site. The abdomen absorbs the fastest, followed by the arms, thighs, and buttocks. Rotating the injection sites within one anatomical area each day may help to maintain consistent insulin absorption. For example, various sites within the back of the left arm may be used throughout the day. The following day, various sites on the abdomen may be used. When possible, allow the patient to choose the injection site. Depending on the agency’s policy, patients may self-administer insulin if it is determined to be safe according to their condition.

Steps for Administration of SQ Injections

Safe administration of SQ injections requires following proper technique. The nurse performs hand hygiene before drawing up the medication and before and after administering the medication. After selecting the appropriate site for an SQ injection, the nurse cleans the skin with an alcohol swab, allowing the skin to dry completely. The nurse holds the syringe at a 45- to 90-degree angle from the site with the bevel up, which allows for smooth introduction of the needle into the SQ tissue (see Figure 12.10). The degree angle and the length of the needle used will depend on the amount of subcutaneous tissue present. A 90-degree angle is used for normal-sized adult patients with adequate fatty tissue or patients who are obese with significant fatty tissue. A 45-degree angle is used for patients who are thin or have minimal fatty tissue.

Before giving the injection, grasp or pinch the skin to pull the tissue away from the muscle. Use caution to ensure the needle does not pierce through the other side of the skin fold and accidentally stick the nurse. Inject the needle into the skin using a quick, dart-like motion and slowly inject the medication at a rate of approximately 10 seconds per mL. Aspiration is not necessary because the likelihood of injecting the medication into a blood vessel is small. After administration, the nurse removes the needle at the same angle in which it was introduced into the skin, applies gentle pressure to the site with a sterile gauze, engages the needle safety device, and discards the syringe in a sharps container. Do not massage the area after the injection because this may cause damage to the underlying tissue.

Link to Learning

You can view how to administer a subcutaneous medication in this video demonstration.

Clinical Safety and Procedures (QSEN): QSEN Competency: Administering a Subcutaneous Injection

See the competency checklist for Administering a Subcutaneous Injection. You can find the checklists on the Student resources tab of your book page on openstax.org.

Needle Size and Syringe Type

When administering a subcutaneous injection, a 25- to 30-gauge needle that is 3/8 to 5/8 in (9.5 to 16 mm) long is used. Some injections may come in a prefilled syringe with the needle attached, while other injections may need to be drawn up from a vial. If the medication is drawn from a vial, a 1 to 3 mL hypodermic syringe is used for most SQ injections. Insulin, however, may only be administered using an insulin syringe. Regardless of the syringe type, always confirm the needle size is appropriate for the patient before administering the medication.