Chapter 7. Parenteral Medication Administration

7.5 Intramuscular Injections

Intramuscular (IM) injections deposit medications into the muscle. The rich blood supply, allows medications to be absorbed faster through muscle fibres than through the subcutaneous route (Malkin, 2008; Ogston-Tuck, 2014a; Perry et al., 2018). The IM site is used for medications that require a quick absorption rate but also a reasonably prolonged action (Rodgers & King, 2000). Due to their rich blood supply, IM injection sites can absorb larger volumes of solution, which means a range of medications, such as sedatives, anti-emetics, hormonal therapies, analgesics, and immunizations, can be administered. In addition, muscle tissue is less sensitive than subcutaneous tissue to irritating solutions and concentrated and viscous medications (Greenway, 2014; Perry et al., 2018; Rodgers & King, 2000).

The technique of IM injections has changed over the past years due to evidence-based research and changes in equipment available for the procedure. An IM site is chosen based on the age and condition of the patient, and the volume and type of medication injected. When choosing a needle size, factors to be considered include the weight of the patient, age, amount of adipose tissue, medication viscosity, and injection site (Hunter, 2008; Perry et al., 2018; Workman, 1999).

Intramuscular injections must be done carefully to avoid complications. Complications with IM include muscle atrophy, injury to bone, cellulitis, sterile abscesses, pain, and nerve injury (Hunter, 2008; Ogston-Tuck, 2014a). With IMs, there is slight risk of injecting the medication directly into the patient’s bloodstream. In addition, any factors that impair blood flow to the local tissue will affect the rate and extent of drug absorption. Because of the adverse and documented effects of pain associated with IM injections, nurses are encouraged to consider other routes first and use the IM route of administration as a last alternative (Perry et al., 2018).

Sites for intramuscular injections include the ventrogluteal, vastus lateralis, and the deltoid site. Literature shows inconsistency in the selection of sites for deep muscular injections: selection may be based on familiarity and confidence rather than on “best practice” (Ogston-Tuck, 2014a). However, there is sufficient evidence that the ventrogluteal IM site is the preferred site whenever possible, and it is an acceptable site for oily and irritating medications. The ventrogluteal site is free from blood vessels and nerves, and it has the greatest thickness of muscle when compared to other sites (Cocoman & Murray, 2008; Malkin, 2008; Ogston-Tuck, 2014a).

A longer needle with a larger gauge is required to penetrate deep muscle tissue. The needle is inserted at a 90-degree angle perpendicular to the patient’s body, or at as close to a 90-degree angle as possible. Use a quick, darting motion when inserting the needle.

Aspiration refers to the action of pulling back on the plunger for five seconds prior to injecting medication (Ipp, Sam, & Parkin, 2006).  Lack of blood in the syringe confirms that the needle is in the muscle and not in a blood vessel. If blood is aspirated, remove the needle, discard it appropriately, and re-prepare and administer the medications (Perry et al., 2014). While aspirating during IM injections is a widespread practice, recent research has found that there is no evidence to support the practice of aspiration (Canadian Agency for Drugs and Technologies in Health, 2014; Greenway, 2014; Sepah, Samad, Altaf, Rajagopalan, & Khan, 2014; Sisson, 2015). This research has not become widespread, and as such nurses are encouraged to consult their agency policy about aspirating when giving an IM injection. Vaccinations and immunizations given by IM injections are never aspirated (Centers for Disease Control, 2015).

The Z-track method is a method of administrating an IM injection that prevents the medication being tracked through the subcutaneous tissue, sealing the medication in the muscle and minimizing irritation from the medication. Using the Z-track technique, the skin is pulled laterally, away from the injection site, before the injection; then the medication is injected, the needle is withdrawn, and the skin is released (Lynn, 2011).

IM Injection Sites

Table 7.6 describes the three injection sites for IM injections.

Table 7.6 Intramuscular Injection Sites


Additional Information

Ventrogluteal  The site involves the gluteus medius and minimus muscle and is the safest injection site for adults and children. The site provides the greatest thickness of gluteal muscles, is free from penetrating nerves and blood vessels, and has a thin layer of fat. To locate the ventrogluteal site, place the patient in a supine or lateral position (on their side). The right hand is used for the left hip, and the left hand is used for the right hip. Place the heel or palm of your hand on the greater trochanter, with the thumb pointed toward the belly button. Extend your index finger to the anterior superior iliac spine and spread your middle finger pointing towards the iliac crest. Insert the needle into the V formed between your index and middle fingers. This is the preferred site for all oily and irritating solutions for patients of any age.

Needle gauge is determined by the solution. An aqueous solution can be given with a 20 to 25 gauge needle. Viscous or oil-based solutions can be given with 18 to 21 gauge needles.

The needle length is based on patient weight and body mass index. A thin adult may require a 16 mm to 25 mm (5/8 to 1 in) needle, while an average adult may require a 25 mm (1 in) needle, and a larger adult (over 70 kg) may require a 25 mm to 38 mm (1 to 1 1/2 in) needle. Children and infants will require shorter needles. Refer to the agency policies regarding needle length for infants, children, and adolescents.

For the ventrogluteal muscle of an average adult, give up to 3 ml of medication.

ventrogluteal intramuscular injection
Figure 7.22 Ventrogluteal intramuscular injection site
Vastus lateralis The vastus lateralis is commonly used for immunizations in children from infants through to toddlers. The muscle is thick and well developed. This muscle is located on the anterior lateral aspect of the thigh and extends from one hand’s breadth above the knee to one hand’s breadth below the greater trochanter. The middle third of the muscle is used for injections. The width of the muscle used extends from the mid-line of the thigh to the mid-line of the outer thigh. To help relax the patient, ask the patient to lie flat with knees slightly bent, or have the patient in a sitting position. The length of the needle is based on the patient’s age, weight, and body mass index. In general, the recommended needle length for an adult is 25 mm to 38 mm (1 to 1 1/2 in). The gauge of the needle is determined by the type of medication administered. Aqueous solutions can be given with a 20 to 25 gauge needle; oily or viscous medication should be administered with 18 to 21 gauge needles. A smaller gauge needle (22 to 25 gauge) should be used with children. The length will be shorter for infants and children; see agency guidelines.

Figure 7.23 Vastus lateralis IM injection site

The maximum amount of medication for a regular sized adult single injection is 3 ml.

Deltoid muscle The deltoid muscle has a triangular shape and is easy to locate and access, but is commonly underdeveloped in adults. Begin by having the patient relax the arm. The patient can be standing, sitting, or lying down. To locate the landmark for the deltoid muscle, expose the upper arm and find the acromion process by palpating the bony prominence. The injection site is in the middle of the deltoid muscle, about 2.5 to 5 cm (1 to 2 in) below the acromion process. To locate this area, lay three fingers across the deltoid muscle and below the acromion process. The injection site is generally three finger widths below, in the middle of the muscle. Select needle length based on age, weight, and body mass. In general, for an adult male weighing 60 to 118 kg (130 to 260 lbs), a 25 mm (1 in) needle is sufficient. For women under 60 kg (130 lbs), a 16 mm (5/8 in) needle is sufficient, while for women between 60 and 90 kg (130 to 200 lbs), a 25 mm (1 in) needle is required. A 38mm (1.5 in) length needle may be required for women over 90 kg (200 lbs) for a deltoid IM injection.

Refer to agency policy regarding specifications for infants, children, adolescents, and immunizations.

The maximum amount of medication for a single injection is generally 1-2 ml but you have to take into account the size of the muscle mass.

For immunizations, a smaller 22 to 25 gauge needle should be used.

Deltoid intramuscular injection
Figure 7.24 Deltoid intramuscular injection site
Deltoid IM injection site
Deltoid IM injection site
Data source: Berman & Snyder, 2016; Davidson & Rourke, 2014; Ogston-Tuck, 2014a; Perry et al., 2018
Special considerations:
  • Avoid muscles that are emaciated or atrophied; they will absorb medications poorly.
  • IM injection sites should be rotated to decrease the risk of hypertrophy.
  • Older adults and thin patients may only tolerate up to 1 ml in a single injection.
  • Choose a site that is free from pain, infection, abrasions, or necrosis.
  • NEVER give an IM injection in the dorsogluteal muscle. If a needle hits the sciatic nerve, the patient may experience partial or permanent paralysis of the leg.

IM Injections

Consider the type of medication and the volume to be injected, the client’s age, general health condition, and size when selecting an IM site. Rotate IM sites to avoid complications. Potential complications include lingering pain, tissue necrosis, abscesses, and injury to blood vessels, bones, or nerves. If administering a vaccination, always refer to the vaccination guidelines for site selection. The Z-track method is recommended to administer IM injections as a way to reduce local tissue irritation (Astle & Duggleby, 2019). It involves displacing the top tissue layers 2.5 to 3.5 cm laterally prior to inserting the needle. After the injection is given, the needle removed and the skin released, the zig-zag path seals the needle track thus preventing the medication from leaking out and irritating tissues. Checklist 59 outlines the steps to perform a Z-track IM injection.


    Checklist 59: Administering a Z -Track Intramuscular Injection

Disclaimer: Always review and follow your agency policy regarding this specific skill.
Safety considerations:
  • Use your knowledge about pharmacokinetics and pharmacodynamics to determine the appropriateness of the ordered medication, dose, and route.
  • Ensure there are no contraindications for this particular patient to receive an IM injection (e.g., circulatory shock, bleeding disorders, anticoagulants).
  • Perform a point of care risk assessment. Always wear gloves to administer IM injections, as there is potential for contact with blood and body fluids.
  • Take all necessary steps to avoid interruptions and distractions when preparing and administering medications.
  • Never leave the medication unsupervised once prepared.
  • If a patient expresses concern or questions the medication, always stop and explore the patient’s concerns and verifying the order if necessary.
  • If required by agency policy, aspirate for blood prior to administering an IM medication.
  • Upon injection, if a patient complains of radiating pain, burning, or a tingling sensation, remove the needle and discard.
  • Whenever possible, chose needleless systems to prepare injectable medication.
  • NEVER recap needles after giving an injection. Engage the needle’s safety system and dispose in the closest sharps container.


 Additional Information

1. Perform hand hygiene. Gather supplies. Supplies include: medication syringe, blunt or blunt fill needle, injection needle with safety system attached, alcohol swab, ampule breaker (if necessary), MAR

Figure 7.25 Supplies for IM injection (vial)
2. Prepare medication as per agency policy. This may include:

  • Check physician orders and MAR to verify medication order.
  • Verify MAR (patient, medication, dose, route, last time of administration).
  • Check your agency’s Parenteral Drug Therapy Manual (PDTM) about guidelines for administration.
  • Independent double check by colleague
  • Verify compatibility if administering two drugs mixed in the same syringe.
Properly identifying medication decreases risk of med error.

Agency protocols are in place to increase patient safety.

Follow principles of asepsis to reduce risk of exposing patient to microorganisms.

Meds that are incompatible or whose compatibility cannot be verified cannot be given simultaneously from the same syringe.

3. Check expiry date and check for particulates, discoloration, or loss of integrity (sterility). Discolored or outdated medication may be harmful. If a medication is discolored or cloudy, always check manufacturer’s specification for the medication.
4. Prepare the medication from the ampule or vial.


 Re-watch the videos: Preparing Medications from a Vial; Preparing Medications from an Ampule developed by Renée Anderson and Wendy McKenzie (2018) of TRU School of Nursing.
5. Label the syringe. Medications prepared away from the bedside must be labelled with two patient identifiers, medication, dose, date and time of preparation, and initials of the nurse to decrease risk of med error.

Medication label sample
6. Perform hand hygiene.

Enter room and introduce yourself. Identify patient using two acceptable identifiers; confirm with MAR; confirm allergies; explain procedure and the medication. Allow the patient time to ask questions.

Hand hygiene reduces transmission of microorganisms.

Identify patient with two identifiers
Compare MAR to patient using two patient identifiers. Verify allergies.

Confirming patient identity reduces risk of med error.

Explaining rationale increases the patient’s knowledge and may reduce any anxiety. Let the patient know there may be mild temporary burning at the injection site.

7. Close curtains or door. This creates privacy for the patient.
8. Reassess patient for any contraindications for the medications Assessment is a prerequisite to the administration of medications.
9. Wear non-sterile gloves. Gloves help prevent exposure to BBF.

Wear non-sterile gloves
10. Select an appropriate site for administration. Prepare the patient in the correct position. Ensure a sharp disposal container is close by for disposal of needle after administration. Site should be free of lesions, rashes, and moles. Choose deltoid, ventrogluteal, or vastus lateralis depending on medication, volume to be injected, and muscle mass.
11. Locate correct site using landmarks, and clean area with alcohol or antiseptic swab (according to agency policy). Use a firm, circular motion. Allow site to dry. Allowing the site to dry renders the antiseptic effective and prevents stinging during injection.

12. Remove needle cap by pulling it straight off the needle. Hold syringe between thumb and forefinger on dominant hand as if holding a dart. This prevents needle from touching side of the cap, prevents contamination, and reduces risk of accidental needle stick injury.

Pulling cap off of needle
Pull cap off of needle
13. Displace skin in a Z-track manner by pulling the skin down or to one side about 2 cm (1 in) with your non-dominant hand.  The Z-track method creates a zig-zag path to prevent medication from leaking into the subcutaneous tissue. This method may be used for all injections, or it may be specified by the medication.

Figure 7.26 Displace the skin 2-3 cm with the non-dominant hand
14. With skin held to one side, quickly insert needle at a 90-degree angle (STAB). After needle pierces skin, continue pulling on skin with non-dominant hand, and at the same time grasp lower end of syringe barrel with fingers of non-dominant hand to stabilize it (GRAB). Move dominant hand to end of plunger.

If required by agency policy, ASPIRATE for blood. If no blood appears, inject the medication slowly.

A quick injection is less painful. Inject medication at approx. 10 seconds/ml. Because the injection sites recommended for immunizations do not contain large blood vessels, aspiration is not necessary when giving vaccines.

Figure 7.27
15. Once medication is given (INJECT), leave the needle in place for 10 seconds. Avoid moving the syringe. Leaving the needle in place allows the medication to be displaced into the tissues.

Movement of the needle can cause additional discomfort for the patient.

16. Once medication is completely injected, remove the needle using a smooth, steady motion. Then release the skin. Using a smooth motion prevents any unnecessary pain to the patient.

Figure 7.28
17. Engage the needle’s safety system immediately.

Cover injection site with sterile gauze / alcohol swab, using gentle pressure. Apply Band-Aid if required. Do not massage site.

Engaging the safety system helps to reduce risk of needle poke and exposure to BBF.

Massage to the site after an IM injection can cause damage to underlying tissue

18. Discard syringe in appropriate sharps container and other supplies in appropriate garbage. Placing sharps in appropriate puncture-proof and leak-proof receptacles prevents accidental needle-stick injuries.

Disposing syringe in sharps container
Dispose of syringe in sharps container
19. Perform hand hygiene. This step prevents the spread of microorganisms.

Hand hygiene with ABHR
Hand hygiene with ABHR
20. Document procedure as per agency policy. Document the medication, time, route, site, date of administration, and effect of the medication; any adverse effects; unexpected outcomes; and any interventions applied.
21. Assess patient’s response to the medication after the appropriate time frame. Assess for effectiveness of the medication (onset, peak, and duration). Assess injection site for pain, bruising, burning, or tingling.
Data source: Centers for Disease Control, 2013, 2015; Perry et al., 2018
Watch the following videos, which were developed by Renée Anderson and Wendy McKenzie Thomspon Rivers University School of Nursing (2018)
Landmarking—Deltoid Administering an IM Injection— Using Z-track 
Landmarking—Ventrogluteal Administering an IM Injection—Using Z-track
Landmarking— Vastus Lateralus Administering IM Injection—Using Z-track    

Critical Thinking Exercises

  1. When giving an IM injection, how can you avoid injury to a patient who is very thin?
  2. Your client has two fractured femurs and a fractured right humerus. Discuss which site(s) are appropriate for IM injection. Discuss other options for pain control.


Figure 7.22.  Ventrogluteal site for IM injection by British Columbia Institute of Technology (BCIT) is licensed under a Creative Commons Attribution 4.0 International License.

Figure 7.23.A medical illustration depicting intramuscular injection sites on an adult’s thigh by BruceBlaus is used under a CC BY-SA 4.0 international license.

Figure 7.24. IM deltoid by British Columbia Institute of Technology (BCIT) is licensed under a Creative Commons Attribution 4.0 International License.

Figure 7.25. Supplies for IM injection (vial) by author is licensed under a Creative Commons Attribution 4.0 International License.

Figure 7.26 – 7.28 Z track from Opentextbc


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