Administer IM Injections in the Deltoid, Not the Buttock
For intramuscular injections in adults, use the deltoid muscle (upper arm) as the preferred site. The deltoid provides easier access, more predictable absorption, and lower risk of complications compared to gluteal sites.
Why the Deltoid is Preferred
For Emergency Medications (Epinephrine)
When administering epinephrine for anaphylaxis, the intramuscular route in the lateral thigh (vastus lateralis) is actually superior to both deltoid and buttock, achieving peak plasma concentrations in 8±2 minutes compared to 34±14 minutes with subcutaneous deltoid injection 1, 2. However, for standard IM injections where the arm is specified, the deltoid is recommended 1.
For Routine Vaccinations and Medications
- Adults and older children should receive IM injections in the deltoid muscle 3, 4
- The deltoid allows for needle lengths >1 inch, which may be necessary to penetrate muscle tissue in certain adults 3
- This site provides consistent muscle penetration even in patients who are overweight or obese 5
For Allergen Immunotherapy
Multiple allergy guidelines consistently recommend subcutaneous injections in the posterior portion of the middle third of the upper arm at the junction of deltoid and triceps muscles 6, 7, 6, 7. This location has greater subcutaneous tissue than adjacent areas and avoids the risks of too-rapid absorption.
Technical Specifications
Injection technique for the deltoid:
- Use a 26-27 gauge needle, ½ to 1 inch length 7
- Insert at 90-degree angle
- Target the middle third of the deltoid muscle
- For safety, a site 5 fingerbreadths (10 cm) below the mid-acromion point minimizes risk of neurovascular injury 8
Why Avoid the Buttock
The gluteal sites (dorsogluteal and ventrogluteal) have significant disadvantages:
- In females, skin-to-muscle depth exceeds 37mm at gluteal sites regardless of obesity status, making standard needles inadequate 5
- Higher risk of sciatic nerve injury with dorsogluteal injections
- Less predictable absorption patterns
- The dorsogluteal site should be reserved only for specific circumstances: when directed by drug package insert, clinical necessity, or patient preference 9
Special Considerations
For long-acting antipsychotics (like paliperidone palmitate): Initial loading doses achieve 20-30% higher exposure when given in the deltoid versus gluteal muscle, though maintenance doses can use either site 10.
For infants and young children: Use the anterolateral thigh (vastus lateralis), not the deltoid or buttock 3.
Common Pitfall to Avoid
Do not confuse subcutaneous immunotherapy technique (which uses the posterior arm at the deltoid-triceps junction) with true intramuscular injections (which target the deltoid muscle itself). Subcutaneous injections require pinching the skin to lift it off the muscle, while IM injections penetrate into the muscle 6, 7.