Intramuscular Naloxone Injection Sites
For intramuscular naloxone administration, inject into the deltoid muscle (upper arm), anterolateral thigh, or ventrogluteal area (upper outer buttock), using standard IM injection technique with the needle inserted at a 90-degree angle. 1
Recommended IM Injection Sites
The American Heart Association guidelines for naloxone administration in opioid-associated emergencies support multiple anatomical sites for IM injection 1:
- Deltoid muscle (middle third posterior aspect of the upper arm) 1
- Anterolateral thigh (upper third anterior lateral aspect) 1
- Ventrogluteal area (upper outer buttock region) 1
Practical Administration Technique
Insert the needle at a 90-degree angle to the skin surface to ensure proper intramuscular delivery 1. The FDA approved naloxone autoinjectors in 2014 specifically for IM administration by both lay rescuers and healthcare providers, making the deltoid and thigh particularly practical sites for emergency use 1.
Clinical Context and Dosing
The typical starting dose for IM naloxone ranges from 0.4 to 2 mg, with the goal of restoring adequate ventilation without precipitating severe opioid withdrawal 1. IM administration has been successfully used in both first aid and advanced life support settings 1.
Response time for IM naloxone averages 3-8 minutes, which is faster than intranasal administration 2, 3. The IM route demonstrates superior efficacy compared to intranasal delivery, with 82% of patients achieving respiratory rate >10/minute within 8 minutes versus 63% with intranasal administration 2.
Important Caveats
- Avoid injecting into areas with lipohypertrophy, scars, or damaged tissue, as absorption will be unpredictable 1
- The effect of naloxone may wear off before the opioid, particularly with long-acting opioids like methadone or fentanyl, requiring repeat dosing and continued monitoring 1, 4
- Patients requiring rescue doses are less common with IM versus intranasal routes (13% vs 26%) 2