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

Maximum Volume for Intramuscular (IM) Injections

The maximum volume for an intramuscular (IM) injection varies by injection site, with generally no more than 5 mL for large muscles in adults, 2-3 mL for the deltoid muscle in adults, and no more than 1 mL for infants and small children.

Volume Limits by Injection Site and Age

Adults:

• Gluteal muscles (ventrogluteal/dorsogluteal): Up to 5 mL
• Vastus lateralis (thigh): Up to 5 mL
• Deltoid muscle: 0.5-2 mL (maximum 3 mL in well-developed adults)

Children:

• Vastus lateralis (thigh): 0.5-1 mL
• Deltoid muscle: 0.5 mL (only if muscle mass is adequate)

Infants (< 12 months):

• Vastus lateralis (thigh): 0.5-1 mL maximum

Factors Affecting IM Injection Volume

Muscle Mass Considerations

The volume that can be safely injected depends primarily on the muscle size and development. The Centers for Disease Control and Prevention (CDC) recommends that injection volume should be appropriate to the size of the muscle 1, 2.

Injection Site Selection

• Preferred sites for adults: Deltoid muscle for routine injections (smaller volumes) and vastus lateralis or ventrogluteal site for larger volumes 2
• Preferred site for infants: Anterolateral aspect of the thigh (vastus lateralis) 1, 2
• Avoid buttocks for injections due to risk of sciatic nerve injury and decreased drug efficacy due to potential subcutaneous deposition 1, 2

Body Composition Considerations

• Subcutaneous fat thickness significantly affects whether an injection reaches muscle tissue 3, 4, 5
• In overweight or obese patients:
  • Standard needle lengths may not reach muscle tissue, particularly in women 5
  • BMI correlates strongly with subcutaneous fat thickness (correlation coefficient 0.82 for women, 0.81 for men) 4
  • Patients with BMI >30 (women) or >35 (men) may require longer needles for successful IM delivery 4

Proper Injection Technique

Needle Selection

• Gauge: 22-25 gauge for all age groups 1, 2
• Length:
  • Adults: 1-1½ inches 1, 2
  • Children/toddlers: 7/8-1¼ inches 1, 2
  • Infants: 7/8-1 inch 1, 2

Injection Angle

• Insert needle at a 90-degree angle to ensure proper muscle penetration 1, 2
• For patients with significant subcutaneous tissue or when using needles >4mm, use a lifted skinfold technique to avoid IM injection 1

Common Pitfalls to Avoid

• Incorrect site selection: Avoid the buttock area due to risk of sciatic nerve injury 1, 2
• Insufficient needle length: May result in subcutaneous rather than intramuscular deposition, affecting drug absorption and efficacy 3, 4, 5
• Excessive volume: Can cause pain, tissue damage, and leakage of medication
• Improper technique: Failure to reach muscle tissue is common, particularly in overweight/obese patients 5

By following these guidelines and considering patient-specific factors such as age, muscle mass, and body composition, healthcare providers can ensure safe and effective administration of intramuscular injections.