Rabies Immunoglobulin Dosing
The recommended dose of human rabies immune globulin (HRIG) is 20 IU/kg (0.133 mL/kg) body weight, administered once on day 0, with the full dose infiltrated around and into the wound(s) if anatomically feasible, and any remaining volume injected intramuscularly at a site distant from the vaccine administration. 1
Dosing Specifications
Weight-based calculation:
- 20 IU/kg body weight for all age groups, including children
- This translates to 0.133 mL/kg
- Do not exceed the recommended dose, as HRIG can partially suppress active antibody production 2
Administration Technique
Wound Infiltration (Critical Step)
If anatomically feasible, infiltrate the full calculated dose around and into all wounds. This is the most important aspect of HRIG administration, as rare failures of postexposure prophylaxis have been reported when inadequate HRIG was infiltrated at exposure sites 2.
- Thoroughly infiltrate the area around and into the wounds
- Recent data shows only 56-57% of eligible patients actually receive proper wound infiltration, representing a significant gap in adherence 3, 4
- Wounds on face/head/torso, hands/fingers, and abrasion-only wounds are less likely to receive infiltration but still require it when feasible 5
- Volume guidance based on wound size: approximately 1 mL for <1 cm wounds, 3 mL for 1-5 cm wounds, and 5 mL for >5 cm wounds 6
Remaining Volume
Any volume that cannot be infiltrated into wounds should be administered intramuscularly at an anatomical site distant from vaccine administration 1:
- Deltoid muscle (upper arm) for adults
- Lateral thigh muscle for children
- Never use the gluteal region due to risk of sciatic nerve injury 7
Critical Timing and Administration Rules
Timing:
- Administer on day 0 (when first vaccine dose is given)
- If not given on day 0, can still be administered up to and including day 7 of the vaccine series
- Beyond day 7, HRIG is not indicated as antibody response to vaccine is presumed to have occurred 2
Separation from vaccine:
- Never administer HRIG in the same syringe or same anatomical site as the first vaccine dose 2, 7
- However, subsequent vaccine doses (days 3,7,14) can be given in the same anatomic location where HRIG was administered 2
Patient Selection
HRIG is indicated for:
- Previously unvaccinated persons with category III exposures (bite or nonbite)
- Both bite and nonbite exposures regardless of time interval between exposure and prophylaxis initiation 1
HRIG is NOT indicated for:
- Previously vaccinated persons with documented history of complete vaccination regimen or documented rabies antibody titer
- These patients receive vaccine only (2 doses on days 0 and 3) 1
Management of IgG Allergy
The provided guidelines do not specifically address severe IgG allergy management. In clinical practice, this represents a rare but serious concern. Given that rabies is 100% fatal without prophylaxis, the risk-benefit strongly favors administration even with allergy history. Consider:
- Premedication with antihistamines and corticosteroids
- Slow administration with close monitoring
- Immediate availability of epinephrine and resuscitation equipment
- Consultation with allergy/immunology if time permits, though rabies prophylaxis should not be delayed
Common Pitfalls to Avoid
- Inadequate wound infiltration - This is the most common error, occurring in 43-44% of cases 3, 4
- Exceeding recommended dose - Can suppress active antibody production 2
- Administering HRIG and vaccine at same site - Reduces vaccine efficacy
- Using gluteal region - Risk of sciatic nerve injury 7
- Giving HRIG to previously vaccinated patients - Unnecessary and potentially harmful
- Administering HRIG after day 7 - No benefit and wastes resources 2
Documentation Requirements
Ensure documentation of:
- Exact dose calculated and administered
- Sites of wound infiltration
- Site of any remaining IM injection
- Timing relative to first vaccine dose
- Patient's vaccination history