Rabies Immunoglobulin Dosing
The recommended dose of rabies immunoglobulin (RIG) for previously unvaccinated patients exposed to rabies is 20 IU/kg body weight, administered once at the beginning of post-exposure prophylaxis. 1, 2, 3
Dosing Specifications
The 20 IU/kg body weight formula is universally applicable to all age groups, including children and adults. 1, 2, 3
This translates to approximately 0.133 mL/kg when using standard human rabies immunoglobulin formulations. 1, 3
Do not exceed the recommended dose, as RIG can partially suppress the active antibody response to the vaccine. 1, 2, 3
Timing of Administration
RIG should be administered at the same time as the first vaccine dose (day 0) whenever possible. 1, 2, 3
If not given initially, RIG can still be administered up to and including day 7 after the first vaccine dose. 1, 2, 3
Beyond day 7, RIG is contraindicated because an antibody response to the vaccine is presumed to have occurred. 1, 2, 3
Administration Technique
If anatomically feasible, infiltrate the full calculated dose thoroughly into and around all wound sites. 1, 2, 3
Any remaining volume after wound infiltration should be injected intramuscularly at a site distant from the vaccine administration site. 1, 2, 3
This infiltration recommendation is critical—rare failures of post-exposure prophylaxis have been documented when inadequate amounts of RIG were infiltrated at exposure sites. 1, 2
Real-world data shows that while adherence to dosing (98%) and timing (100%) is excellent, only 56% of eligible patients receive proper wound infiltration, representing a significant gap in optimal care. 4
Critical Precautions
Never administer RIG in the same syringe, needle, or anatomical site as the first vaccine dose. 1, 2, 3
However, subsequent vaccine doses in the series can be given at the same anatomic location where RIG was previously administered. 1
Avoid the gluteal region for intramuscular injection due to risk of sciatic nerve injury. 3
Preferred sites for the intramuscular portion are the deltoid muscle in adults or the lateral thigh muscle in children. 3
Vaccine Schedule Considerations
Previously unvaccinated persons require RIG plus a 4-dose vaccine series (days 0,3,7, and 14) according to current recommendations. 2, 5
Immunocompromised patients still require the 5-dose vaccine schedule (days 0,3,7,14, and 28) along with RIG. 2, 5
Previously vaccinated persons require only vaccine (2 doses on days 0 and 3) and should NOT receive RIG. 1, 2, 5, 3
Common Pitfalls to Avoid
Underdosing or failing to infiltrate wounds: The most common error is administering all RIG intramuscularly without wound infiltration when wounds are present and accessible. 4
Delaying RIG beyond day 7: Once the 7-day window closes, RIG administration may interfere with the established vaccine response without providing benefit. 1, 2
Administering RIG to previously vaccinated individuals: This is unnecessary and wastes resources, as these patients have immunologic memory. 1, 3
Using the same injection site for RIG and vaccine: This can compromise the immune response to the vaccine. 1, 2, 3