What is the appropriate intramuscular injection site for ceftriaxone in an 18‑month‑old child?

Intramuscular Injection Site for Ceftriaxone in an 18-Month-Old

For an 18-month-old child, administer ceftriaxone intramuscularly into the anterolateral aspect of the thigh. 1

Primary Injection Site

• The anterolateral thigh is the preferred and recommended site for intramuscular injections in infants and young children, including 18-month-olds. 1, 2
• This site is specifically endorsed by the American Academy of Pediatrics and CDC guidelines for vaccine and medication administration in this age group. 1
• The vastus lateralis muscle (middle of the anterolateral thigh) provides adequate muscle mass with low risk of vascular or nerve damage in young children. 3

Technical Administration Details

• Use a needle size of 22-25 gauge with appropriate length (typically 1 inch) to ensure proper muscle penetration in toddlers. 2
• The injection should be administered deep into the muscle mass to avoid subcutaneous deposition, which can reduce absorption and increase local reactions. 2
• For standard pediatric doses of ceftriaxone (typically 50 mg/kg for serious infections, not exceeding adult dosing), the volume is usually manageable in a single thigh injection site. 4

Sites to Avoid

• Do not use the buttock for ceftriaxone administration due to risk of sciatic nerve injury and decreased drug absorption. 2
• The deltoid muscle is not appropriate for an 18-month-old child, as it lacks adequate muscle mass at this age and is reserved for children ≥3 years old. 1, 5

Volume Considerations

• The anterolateral thigh can accommodate volumes up to 1-2 mL in toddlers, which is sufficient for most pediatric ceftriaxone doses. 5
• If the calculated dose requires a larger volume that exceeds safe limits for a single site, consider dividing the dose between both thighs. 2

Clinical Context

• Ceftriaxone is rapidly and completely absorbed following intramuscular administration, with bioavailability equivalent to intravenous dosing by 2.5 hours post-injection. 6
• Parents should be informed that intramuscular ceftriaxone injection can be painful, but the anterolateral thigh site minimizes risk of serious complications. 4
• The long half-life of ceftriaxone (allowing once-daily dosing in most cases) makes the discomfort of intramuscular injection more acceptable compared to multiple daily injections. 7, 8