Intramuscular (IM)

Definition

Intramuscular (IM) injection is the administration of medication directly into muscle tissue, where it is absorbed into the bloodstream.

Common Sites

• Ventrogluteal (preferred for adults): Safer. Away from major nerves/vessels.
• Deltoid: Small volume (1 mL); vaccines.
• Vastus lateralis: PREFERRED for infants.
• Dorsogluteal: No longer recommended (sciatic nerve risk).

Needle Selection

• Adults: 21 to 23 gauge, 1 to 1.5 inches
• Children: 22 to 25 gauge, 5/8 to 1 inch
• Infants: 22 to 25 gauge, 5/8 inch in vastus lateralis

Technique

• Angle: 90°
• Max volume: deltoid 1 mL; other sites up to 3 mL (adults)
• Z-track technique for irritating medications (iron dextran)
• Clean site with alcohol, allow to dry
• Aspiration generally no longer required for vaccines

NCLEX Relevance

Vastus lateralis for infants. Ventrogluteal preferred for adults.