Hepatitis B Immunoglobulin Adult Dose
For post-exposure prophylaxis in adults, administer 0.06 mL/kg of body weight intramuscularly as soon as possible after exposure, ideally within 24 hours but no later than 7 days. 1
Dosing by Exposure Type
Percutaneous or Mucosal Exposure (Needlestick, Splash)
Unvaccinated or incompletely vaccinated adults:
- Single dose of HBIG 0.06 mL/kg IM immediately after exposure (within 24 hours if possible)
- Administer simultaneously with hepatitis B vaccine at a separate anatomical site 2, 1
- Complete the vaccine series at 1 and 6 months
Vaccinated adults with inadequate antibody response (<10 mIU/mL):
- Single dose of HBIG 0.06 mL/kg IM plus vaccine booster dose, OR
- Two doses of HBIG 0.06 mL/kg IM: first dose immediately, second dose 1 month later 2, 1
Vaccine non-responders (after 2 complete vaccine series):
- Two doses of HBIG 0.06 mL/kg IM: first dose immediately after exposure, second dose 1 month later 2
- No additional vaccine doses recommended
Sexual Exposure to HBsAg-Positive Person
- Single dose of HBIG 0.06 mL/kg IM within 14 days of last sexual contact 1
- Initiate hepatitis B vaccine series simultaneously at a different site
Critical Timing Considerations
The effectiveness of HBIG diminishes significantly with delayed administration. Maximum benefit occurs when given within 24 hours of exposure, with efficacy declining substantially after 7 days 1. For percutaneous exposures, the protective efficacy is approximately 75% when administered appropriately 1, 3.
Important Clinical Pitfalls
Do not administer HBIG intravenously - it must be given intramuscularly only 1. When combining HBIG with hepatitis B vaccine, always use separate anatomical sites (e.g., different limbs) to avoid potential interference with vaccine immunogenicity 2, 1.
For persons who refuse hepatitis B vaccine, a second dose of HBIG should be administered 1 month after the first dose 1.
Combination Therapy Rationale
The combination of HBIG with hepatitis B vaccine is superior to HBIG alone because it provides both immediate passive protection and long-term active immunity 2, 1. This combined passive-active approach is the treatment of choice for all post-exposure scenarios where prophylaxis is indicated 4, 1.