What is the maximum recommended volume for an intramuscular (IM) injection?

Maximum Volume for Intramuscular Injection

The maximum recommended volume for IM injection is 0.5 mL in the deltoid muscle for adults and children ≥3 years, and up to 5 mL in the vastus lateralis (anterolateral thigh) or ventrogluteal sites for adults, with volumes varying by injection site and patient age. 1

Site-Specific Volume Limits

Deltoid Muscle

• Maximum 0.5 mL for adults and children ≥3 years of age 1
• Smaller volumes (0.25 mL) are used for infants 6-35 months depending on the specific vaccine product 1
• Larger volumes risk inadequate muscle penetration, subcutaneous deposition, local pain, reduced absorption, and increased adverse reactions 1

Anterolateral Thigh (Vastus Lateralis)

• Preferred site for volumes exceeding 0.5 mL in adults 1
• Accommodates larger volumes and provides more rapid absorption for certain medications compared to deltoid 1
• Recommended as the primary site for infants and young children for all IM injections 2, 1
• Maximum volume in rodent models is 50 μL using the finest needle possible (27G or smaller) 2

Dorsogluteal Site

• Generally not recommended due to risk of sciatic nerve injury and decreased immunogenicity 3
• When used, requires careful attention to subcutaneous tissue thickness—women with BMI ≥25 require needles >38 mm (1.5 inches) to reach muscle 4
• High failure rate: in one study, 23 of 60 patients (38%) had medication deposited in subcutaneous tissue rather than muscle despite using 38.1 mm needles 5

Age-Specific Recommendations

Infants and Young Children (6-35 months)

• 0.25 mL or 0.5 mL depending on vaccine product 1
• Anterolateral thigh is the preferred injection site 2, 1
• Never split a 0.5 mL prefilled syringe into two 0.25 mL doses due to sterility concerns 1

Children ≥3 Years and Adults

• 0.5 mL maximum in deltoid 1
• Deltoid becomes the preferred site once adequate muscle mass is present 1, 3

Critical Safety Considerations

Needle Length Selection

• Needle length must be sufficient to penetrate subcutaneous tissue and reach muscle 1, 3
• For obese patients, longer needles are required: arm circumference >35 cm (men) or >30 cm (women) should prompt selection of longer needles 6
• Standard 25 mm needles may be inadequate in patients with BMI >25 (women) or >35 (men) for dorsogluteal injections 4

Common Pitfalls to Avoid

• Using too short a needle in obese patients, resulting in subcutaneous rather than intramuscular deposition 3, 5
• Exceeding 0.5 mL in the deltoid, which increases risk of local complications 1
• Poor landmarking technique, which frequently results in improperly placed injections even with appropriate needle length 4
• Using the same needle length for all patients regardless of body habitus 3

Special Clinical Scenarios

Epinephrine for Anaphylaxis:

• Dose is 0.01 mg/kg of 1:1000 solution (maximum 0.5 mg adults, 0.3 mg children) 2
• Anterolateral thigh is preferred over deltoid for intramuscular epinephrine administration, though comparative studies between IM thigh vs. IM arm are limited 2
• Auto-injector doses of 0.1 mg, 0.15 mg, or 0.3 mg are available, with 0.15 mg widely prescribed for infants despite being above the 0.01 mg/kg recommendation for smaller infants 2

When Volumes Exceed Site Capacity:

• Consider alternative injection sites (vastus lateralis accommodates larger volumes) 1
• Consider dividing the dose between two separate injection sites if clinically appropriate
• Ultrasound guidance may be warranted when skin-to-muscle depth is questionable 4