Paracetamol (Acetaminophen) for Post-Vaccination Prophylaxis
Paracetamol (acetaminophen) is recommended as prophylaxis after vaccination, particularly for children with a history of seizures or those with a family history of convulsions, at a dose of 15 mg/kg at the time of vaccination and every 4 hours for 24 hours to reduce post-vaccination fever. 1
Recommended Prophylactic Use
When to Use Prophylactic Paracetamol
- Recommended for:
Dosing Regimen
- Dose: 15 mg/kg of paracetamol 2, 1
- Timing: Administer at the time of vaccination and every 4 hours for 24 hours 1
- Formulation: For infants, use appropriate pediatric formulations (syrup 125mg/5ml) 1
Efficacy of Prophylactic Paracetamol
Prophylactic paracetamol has demonstrated effectiveness in:
- Reducing the incidence of fever ≥38°C after vaccination, particularly during the infant series (43% efficacy) 3
- Significantly decreasing fever and irritability in the first 6 hours post-vaccination 4
- Reducing fever >39°C after toddler booster doses 3
- Decreasing the likelihood of children being reported as "much more fussy than usual" (58% reduction) 5
Important Considerations and Cautions
Potential Impact on Immune Response
- Some research suggests prophylactic paracetamol may lower antibody responses to certain vaccine antigens 6, 7
- This effect appears more pronounced when paracetamol is given prophylactically (at time of vaccination) rather than therapeutically (after symptoms develop) 7
Safety Considerations
- The recommended 15 mg/kg dose has a favorable safety profile when used short-term 1
- Single doses should never exceed 15 mg/kg, with total daily dose not exceeding 60 mg/kg/day 1
Common Pitfalls to Avoid
- Using subtherapeutic doses (≤10 mg/kg) reduces effectiveness 1
- Failing to administer the first dose at the time of vaccination decreases prophylactic benefit 1
- Using adult formulations or incorrect concentrations for infants 1
- Not adjusting the dose based on the infant's weight 1
Conclusion
For most routine vaccinations, prophylactic paracetamol at 15 mg/kg at the time of vaccination and every 4 hours for 24 hours is effective for preventing post-vaccination fever and discomfort. It is particularly important for children with a history of seizures or family history of convulsions. While there are some concerns about potential effects on antibody response, the clinical significance of this finding remains uncertain, and the benefits of fever prevention in high-risk children outweigh these theoretical concerns.