Injection Techniques and Needle Sizes for Various Age Groups and Injection Types

Intramuscular Injections

The Centers for Disease Control and Prevention recommends using 22-25 gauge needles with length varying by age: 7/8-1 inch for infants, 7/8-1¼ inches for children, and 1-1½ inches for adults for intramuscular injections 1, 2, 3
The deltoid muscle is the preferred site for routine intramuscular injections in adults 1
The anterolateral thigh is an acceptable alternative site for intramuscular injections in adults and the preferred site for infants and toddlers 1, 3
The needle must be long enough to reach muscle mass and prevent seepage into subcutaneous tissue, but not so long as to involve nerves, blood vessels, or bone 1, 2
For children and adolescents, 22-25 gauge needles, 7/8-1¼ inches in length, are recommended for intramuscular injections 1, 2, 3
For infants, 22-25 gauge needles, 7/8-1 inch in length, are recommended for intramuscular injections 1, 2, 3

The American Diabetes Association recommends using 4-mm pen needles inserted at 90° for all patients regardless of age, sex, ethnicity, or BMI for subcutaneous injections 5, 6, 7
The abdomen, thighs, buttocks, and upper arm are suitable sites for subcutaneous injections, with specific guidelines for each site 5, 6
Lean patients with BMI <19 kg/m² should use a lifted skinfold with 4-mm needles to prevent intramuscular injection 7
Children and young adults are at higher risk for accidental intramuscular injection and should use a 2-finger lifted skinfold 5, 6

The Centers for Disease Control and Prevention recommends using 25-27 gauge needles, 3/8-3/4 inch in length, for intradermal injections 1, 3
Intradermal injections should be administered on the volar surface of the forearm with the bevel facing upward at an angle parallel to the long axis of the forearm 1, 3

The Centers for Disease Control and Prevention advises against using the buttock routinely for intramuscular injections due to sciatic nerve injury risk and decreased vaccine immunogenicity 1, 4
Areas with lipohypertrophy, scars, or tissue abnormalities should be avoided for injections 5, 6
Proper site rotation should be maintained for patients requiring frequent injections 8

Pen needles with contoured bases are recommended to reduce injection force and pain 7
32-gauge needles are recommended for most adults with diabetes for reduced pain 7
5-bevel needle tips are preferred over 3-bevel tips to minimize skin penetration force 7