Intramuscular (IM) Injection


The anterolateral thigh is the preferred site for IM injection in infants under 12 months of age.

Medications are injected into the bulkiest part of the vastus lateralis thigh muscle, which is the junction of the upper and middle thirds of this muscle.

Nursing and medical staff must be familiar with the principles of the administration of medications to an infant. These principles include

  • observation of standard precautions
  • aseptic techniques and correct drug/dose/time/route/patient practices


  • IM medication ampoule
  • Large bore needle for withdrawing medication from ampoule
  • 1 ml or 2 ml syringe
  • 23 gauge 25 mm needle or 25 gauge 16 mm needle for preterm babies 2 months or younger
  • Cotton wool swab
  • Gloves for standard precautions


There must be a written medication order on the medication chart.

Check the correct drug/dose/time/route/infant.

Draw the medication up into the syringe using the large bore needle.

Change to the 23 g 25 mm needle or 25 g 16 mm needle.

A second staff member to help position the infant on his/her back on a table or bed may be required.

Undo the infant’s nappy to locate the junction of the upper and middle thirds of the vastus lateralis thigh muscle.

The clinician performing the injection places their forearm across the infant’s pelvis and secures the thigh between their thumb and forefinger.

Bunch up the thigh muscle to increase the muscle mass.

Administer the IM injection at a 45-60° angle to the skin. The needle must be angled toward the knee. At this angle, the needle can be safely inserted to a depth of between 16-25 mm skin-to-needle-tip depth. Inserting the needle at this angle results in less tissue resistance as the needle penetrates the muscle. The following figures of the thigh show the recommended injection site.

Diagram of the muscles of the thigh showing the recommended  injection site

Figure 1: Diagram of the muscles of the thigh showing the recommended injection site. (NHMRC, 2000, p. 10)

Diagramtic cross section of the thigh showing recommended  injection site

Figure 2: Diagramiatic cross section of the thigh showing recommended injection site. (NHMRC, 2000, p. 10)

Withdraw the plunger to ensure that the medication does not go directly into a blood vessel.

Slowly inject the medication for even distribution and to minimise the infant's discomfort.

Remove the needle.

Check the injection site for bleeding and apply cotton wool ball if necessary. Observe the site for local inflammation.

Dispose of the needles and syringe into a labeled puncture proof container to prevent needle stick injury & reuse.

Document the administration of the IM injection on the medication chart and/or child health record (where appropriate).

Practice Points

Avoid subcutaneous and intramuscular injections when intravenous administration is a suitable alternative option. Note that VitaminK is preferably given intramuscularly as soon as possible after birth and endogenous endorphins are present at high levels at the time of birth.

Alcohol and other disinfecting agents must be allowed to evaporate before injection of medication.

Never give an IM injection in the buttocks. Using the vastus lateralis muscle avoids the risk of sciatic nerve damage from gluteal injection. Also the vastus lateralis muscle has a larger muscle mass than the gluteal region and therefore has reduced risk of severe local reactions. The deltoid in infants is not sufficiently bulky to absorb IM medications adequately. The vastus lateralis muscle avoids the thicker layer of subcutaneous fat on the anterior thigh.

It is important that infants do not move during the IM injection. However excessive restraint can increase the infant’s fear and can result in increased muscle tension

The infant can be held in the ‘cuddle’ or semi-recumbent position on the lap of the parent/caregiver/health professional.

Oral sucrose may be given for relief of distress (link to section).

The volume of the IM injection should not be more than 1ml.

When two IM injections are being administered, give one medication into the right thigh and the other into the left thigh.


NHMRC (2000). The Australian Immunisation Handbook (7th ed). Canberra: Australian Government Publishing Services.