Intramuscular injections deliver medication through the skin and subcutaneous tissues into certain muscles. Muscles have a larger and a greater number of blood vessels than subcutaneous tissue, allowing faster onset of action than with subcutaneous injections. An intramuscular injection is chosen when a reasonably rapid systemic uptake of the drug is needed by the body and when a relatively prolonged action is required. Some medications administered intramuscularly are formulated to have a longer duration of effect. The deposit of medication creates a depot at the injection site, designed to deliver slow, sustained release over hours, days, or weeks.

It is important to choose the right needle length for a particular intramuscular injection. Needle length should be based on the individual patient. (See Table 5-1 for intramuscular needle length recommendations.) Patients who are obese may require a longer needle (Wolicki & Miller, 2020), and emaciated patients may require a shorter needle. Appropriate gauge is determined by the medication being administered. In general, biologic agents and medications in aqueous solutions should be administered with a 20- to 25-gauge needle. Medications in oil-based solutions should be administered with an 18- to 25-gauge needle. Many medications come in prefilled syringe units. If a needle is provided on the prefilled unit, ensure that the needle on the unit is the appropriate length for the patient and situation.

To avoid complications, the nurse must be able to identify anatomic landmarks and site boundaries. See Figure 1 for a depiction of anatomic landmarks and site boundaries for potential intramuscular injection sites. Consider the age of the patient, medication type, and medication volume when selecting an intramuscular injection site. (See Table 5-2 for information related to intramuscular site selection.) Rotate the sites used to administer intramuscular medications when therapy requires repeated injections. Depending on the site selected, it may be necessary to reposition the patient (refer to Table 5-3).

Administer the intramuscular injection so that the needle is perpendicular to the patient's body. This ensures it is given using a 90-degree angle of injection (CDC, 2021). Figure 5-1 in the chapter opener on page 200 shows the angle of insertion for intramuscular injections.

The medication volume that can be administered intramuscularly varies based on the intended site. In general, 1 to 5 mL is the accepted volume range, with a limitation of 1 mL of solution at the deltoid site. However, up to 2 mL may be administered at the deltoid site, depending on the size of the individual patient's muscle (Gutierrez & Munakomi, 2021). The less-developed muscles of children and older people limit the intramuscular injection to 1 to 2 mL.

Many of the drugs given intramuscularly can cause irritation to subcutaneous tissues when backflow into the tissues occurs along the injection track. Therefore, the Z-track technique is recommended for all intramuscular injections (particularly nonvaccine injections) to ensure that medication does not leak back along the needle track and into the subcutaneous tissue (Hopkins & Arias, 2013; Karch, 2020; Yilmaz et al., 2016). This technique reduces pain and discomfort (Şanlialp Zeyrek et al., 2019), particularly for patients receiving injections over an extended period. The Z-track method is also suggested for older adults who have decreased muscle mass. Some medications, such as iron, are best given via the Z-track method due to the irritation and discoloration associated with the medication (Karch, 2020). An alternative method for intramuscular injection is to stretch the skin flat between two fingers and hold it taut for needle insertion. The decision regarding use of the Z-track method or stretching the skin at the site is based on the individual patient and nursing judgment (Taylor et al., 2023). Knowledge of landmarks and risks, along with an assessment of muscle size and consideration of the medication itself are of paramount importance for the nurse.

Aspiration, or pulling back on the plunger to check if a blood vessel has been entered, is not necessary and has not proved to be a reliable indicator of needle placement. The use of correct technique and recommended anatomic injection sites results in a very small likelihood of injecting into a blood vessel and there is no scientific evidence to support aspiration (CDC, 2021; Davidson & Rourke, 2013; Sisson, 2015). The World Health Organization (WHO, 2020) and CDC (2015a) do not include aspiration in the steps for intramuscular injection of vaccines. The wide-spread use of auto-disable (AD) syringes encouraged by the WHO (2020) further reinforces no aspiration with intramuscular vaccine administration, since most AD syringes are not designed to aspirate (Sepah et al., 2017). Some medication manufacturers indicate that aspiration may be recommended when administering certain medications, at certain dosages and certain rates, but more research needs to be done on this topic (Mraz et al., 2018; Sepah et al., 2017; Thomas et al., 2016). Consult facility policy and manufacturer recommendations to ensure safe administration.

Refer to Box 5-1 in Skill 5-7 on page 237 for techniques for reducing discomfort when injecting medications subcutaneously or intramuscularly.

The following skill outlines administration of an intramuscular injection using the Z-track technique. If, based on assessment of the particular circumstances for an individual patient, the nurse decides not to use the Z-track technique, the skin should be stretched flat between two fingers and held taut for needle insertion.

Assessment

Assess the appropriateness of the drug for the patient. Review the medical history and allergy, assessment, and laboratory data that may influence drug administration. Check the expiration date. Assess the site on the patient where the injection is to be given. Avoid any site that is bruised, tender, hard, swollen, inflamed, or scarred. Assess the patient's knowledge of the medication. If the patient has deficient knowledge about the medication, this may be the appropriate time to begin education about it. If the medication may affect the patient's vital signs, assess them before administration. If the medication is intended for pain relief, assess the patient's pain before and after administration. Verify patient name, dose, route, and time of administration.

Actual or Potential Health Problems and Needs

Many actual or potential health problems or issues may require the use of this skill as part of related interventions. An appropriate health problem or issue may include:

• Knowledge deficiency
• Injury risk
• Infection risk

Outcome Identification and Planning

The expected outcomes to achieve when administering an intramuscular injection are that the patient receives the medication via the intramuscular route and experiences the intended effect of the medication, the patient does not experience adverse effects, and the patient verbalizes an understanding of the medication regimen.

Implementation

Action	Rationale
1. Gather equipment. Check each medication prescribed against the original in the health record, depending on facility policy and the medication order system in place. Clarify any inconsistencies. Check the patient's health record for allergies.	The prescription is the legal record of prescribed medication interventions. This comparison helps to identify errors that may have occurred when orders were transcribed. Computer provider order-entry (CPOE) systems allow prescribers to send electronic medication prescriptions directly to the pharmacy located in a health care facility and to outpatient pharmacies.
2. Know the actions, special nursing considerations, safe dose ranges, purpose of administration, and adverse effects of the medications to be administered. Consider the appropriateness of the medication for this patient.	This knowledge aids the nurse in evaluating the therapeutic effect of the medication in relation to the patient's health status and can also be used to educate the patient about the medication.
3. Perform hand hygiene.	Hand hygiene prevents the spread of microorganisms.
4. Move the medication supply system to the outside of the patient's room or prepare for administration at the medication supply system in the medication area. Alternatively, access the medication administration supply system at or inside the patient's room.	Organization facilitates error-free administration and saves time.
5. Unlock the medication supply system or drawer. Enter the passcode and scan employee identification, if required.	Locking the medication supply system or drawer safeguards each patient's medication supply. Facility accrediting organizations require medication supply systems to be locked when not in use. Entering the passcode and scanning ID allows only authorized users into the system and identifies the user for documentation by the computer.
6. Prepare medications for one patient at a time.	This prevents errors in medication administration.
7. Read the eMAR/MAR and read the label when selecting the proper medication from the medication supply system or the patient's medication drawer.	This is the first check of the label.
8. Read the label and compare the label with the eMAR/MAR. Check expiration dates and perform calculations, if necessary. Scan the bar code on the package, if required.	This is the second check of the label. Verify calculations with another nurse to ensure safety, if necessary.
9. If necessary, withdraw the medication from an ampule or vial as described in Skills 5-3 and 5-4.
10. Depending on facility policy, the third check of the label may occur at this point. If so, when all medications for one patient have been prepared, read the label and recheck the labels with the eMAR/MAR before taking the medications to the patient. However, many facilities require the third check to occur at the bedside, after identifying the patient.	This third check ensures accuracy and helps to prevent errors. Note: Many facilities require the third check to occur at the bedside, after identifying the patient and before administration.
11. Label the syringe with the medication's name, dose, and amount (The Joint Commission, 2021).	Unlabeled syringes are unidentifiable and may lead to a medication administration error (The Joint Commission, 2021).
12. Log out of and/or lock the medication supply system before leaving it.	Locking the medication supply system or drawer safeguards the patient's medication supply. Facility accrediting organizations require medication supply systems to be locked when not in use.
13. Transport medications to the patient's bedside carefully and keep the medications in sight at all times.	Careful handling and close observation prevent accidental or deliberate disarrangement of medications.
14. Ensure that the patient receives the medications at the correct time.	Check facility policy, which may allow for administration within a period of 30 minutes before or 30 minutes after the designated time.
15. Perform hand hygiene and put on PPE, if indicated.	Hand hygiene and PPE prevent the spread of microorganisms. PPE is required based on transmission precautions.
16. Identify the patient. Compare the information with the eMAR/MAR. The patient should be identified using at least two of the following methods (The Joint Commission, 2021):	Identifying the patient ensures the right patient receives the medications and helps prevent errors. The patient's room number or physical location is not used as an identifier (The Joint Commission, 2021). Replace the identification band if it is missing or inaccurate in any way.
a. Check the name on the patient's identification band.	This requires a response from the patient, but illness and strange surroundings often cause patients to be confused.
b. Check the identification number on the patient's identification band.
c. Check the birth date on the patient's identification band.
d. Ask the patient to state their name and birth date, based on facility policy.
17. Close the door to the room or pull the bedside curtain.	This provides patient privacy.
18. Complete necessary assessments before administering medications. Check the patient's allergy bracelet, if present, or ask the patient about allergies. Explain the purpose and action of the medication to the patient.	Assessment is a prerequisite to administration of medications. Explanation provides rationale, increases knowledge, promotes patient engagement, and reduces anxiety.
19. Scan the bar code on the patient's identification band, if required (Figure 2) (The Joint Commission, 2021).	This provides an additional check to ensure that the medication is given to the right patient.
20. Based on facility policy, the third check of the label may occur at this point. If so, read the label and recheck the labels with the eMAR/MAR before administering the medications to the patient.	Many facilities require the third check to occur at the bedside, after identifying the patient and before administration. If facility policy directs the third check at this time, this third check ensures accuracy and helps to prevent errors.
21. Put on gloves.	Gloves help prevent exposure to contaminants.
22. Select an appropriate administration site. Assist the patient to the appropriate position for the site chosen. Refer to Table 5-3. Drape, as needed, to expose only the site area being used.	Selecting the appropriate site and appropriate positioning prevent injury. Draping provides privacy and warmth.
23. Identify the appropriate landmarks and site boundaries for the site chosen (Figure 3).	Good visualization is necessary to establish the correct site location and to avoid complications (Taylor et al., 2023).
24. Cleanse the site with an antimicrobial swab while wiping with a firm, circular motion and moving outward from the injection site. Consider leaving the alcohol pad on the skin with the tip of the pad pointing toward the center of the area you just prepared. Allow the skin to dry.	Pathogens on the skin can be forced into the tissues by the needle. Moving from the center outward prevents contamination of the site. Allowing the antimicrobial solution to dry completely (5 to 20 seconds) ensures complete antimicrobial effectiveness (Gorski et al., 2021; Slater et al., 2018), and prevents introducing alcohol into the tissue, which can be irritating and uncomfortable.
25. Remove the needle cap by pulling it straight off. Hold the syringe in your dominant hand between the thumb and forefinger.	This technique lessens the risk of an accidental needlestick and also prevents inadvertently unscrewing the needle from the barrel of the syringe.
26. Displace the skin in a Z-track manner. Pull or shift the skin and underlying tissue down or to one side 1 to 2 cm (Karch, 2020; Yilmaz et al., 2016) with your nondominant hand and hold the skin and tissue in this position (Figure 4). Alternatively, based on assessment of the particular circumstances for an individual patient, if the nurse decides not to use the Z-track technique, the skin should be stretched flat between two fingers and held taut for needle insertion.	Z-track technique is recommended for all intramuscular injections to ensure medication does not leak back along the needle track and into the subcutaneous tissue (Hopkins & Arias, 2013; Yilmaz et al., 2016). This technique reduces pain and discomfort, particularly for patients receiving injections over an extended period. The Z-track method is also suggested for older adults who have decreased muscle mass. Some agents, such as iron, are best given via the Z-track method due to the irritation and discoloration associated with this agent.
27. Quickly dart the needle into the tissue so that the needle is perpendicular to the patient's body, administering at an angle of 90 degrees (CDC, 2021) (Figure 5).	A quick injection is less painful. Inserting the needle at a 90-degree angle facilitates entry into muscle tissue.
28. As soon as the needle is in place, use the thumb and forefinger of your nondominant hand to hold the lower end of the syringe, taking care to maintain the displacement of the skin and tissue. Slide your dominant hand to the end of the plunger. Inject the solution slowly.	Moving the syringe could cause damage to the tissues and inadvertent administration into an incorrect area. Rapid injection of the solution creates pressure in the tissues, resulting in discomfort.
29. Once the medication has been instilled, wait 10 seconds before withdrawing the needle.	This allows medication to begin to diffuse into the surrounding muscle tissue (Gutierrez & Munakomi, 2021).
30. Withdraw the needle smoothly and steadily at the same angle at which it was inserted, supporting tissue around the injection site with your nondominant hand. Remove the hand holding the displaced skin and tissue only after removal of the needle, allowing the displaced skin and tissue to return to its normal position.	Slow withdrawal of the needle pulls the tissues and causes discomfort. Applying counter traction around the injection site helps to prevent pulling on the tissue as the needle is withdrawn. Removing the needle at the same angle at which it was inserted minimizes tissue damage and discomfort for the patient. Allowing displaced skin and tissue to move back into place while needle is still inserted causes damage to the tissues.
31. Do not recap the used needle. Engage the safety shield or needle guard.	A safety shield or needle guard prevents accidental needlestick.
32. Apply gentle pressure at the site with a dry gauze (Figure 6). Do not massage the site.	Light pressure causes less trauma and irritation to the tissues. Massaging can force medication into subcutaneous tissues and increase discomfort.
33. Remove gloves and perform hand hygiene. Assist the patient to a position of comfort.	Removing gloves and performing hand hygiene reduces the risk of contamination of other items and the spread of microorganisms. Assisting the patient to a position of comfort promotes patient comfort.
34. Discard the needle and syringe in the appropriate container, such as a sharps receptacle.	Proper disposal of the needle prevents injury.
35. Remove gloves and additional PPE, if used. Perform hand hygiene.	Proper removal of PPE reduces the risk of infection transmission and contamination of other items. Hand hygiene prevents the spread of microorganisms.
36. Document the administration of the medication immediately after administration. See Documentation section below.	Timely documentation helps to ensure patient safety.
37. Evaluate the patient's response to the medication within the appropriate time frame. Assess site, if possible, within 2 to 4 hours after administration.	The patient needs to be evaluated for therapeutic and adverse effects from the medication. Visualization of the site allows for assessment of any untoward effects.

Evaluation

The expected outcomes have been met when the patient has received the medication via the intramuscular route and experienced the intended effect of the medication, the patient did not experience adverse effects, and the patient has verbalized an understanding of the medication regimen.