From the Guidelines
Fever after vaccination is a normal and common side effect in a 6-month-old, especially within the first 24-48 hours, as long as it is mild to moderate (up to 102°F or 38.9°C) 1. For mild to moderate fever, you can give infant acetaminophen (Tylenol) at a dose of 10-15 mg per kg of body weight every 4-6 hours as needed. Some key points to consider when managing fever after vaccination in a 6-month-old include:
- Keeping the baby comfortable with light clothing
- Ensuring they stay hydrated with regular breast milk or formula
- Monitoring the fever
- Contacting the pediatrician if the fever exceeds 102°F (38.9°C), lasts more than 48 hours, or if the baby seems unusually irritable, lethargic, or has decreased feeding 1. It's also important to note that fever after vaccination is actually a sign that the baby's immune system is responding appropriately to the vaccine by building protection. However, it's crucial to be aware of the potential for more serious infections, especially in young infants, and to seek medical attention if there are any concerns 1.
From the Research
Fever after Vaccination in 6-month-old Infants
- Fever is a common side effect after vaccination, especially in infants and young children 2.
- The time pattern of fever attributable to immunization has characteristic features depending on the vaccine used 2.
- A study found that routine prophylactic acetaminophen after DPT vaccination was effective in reducing the frequency of fever and irritability in the initial 6 hours 3.
- Another study suggested that acetaminophen may reduce the risk of post-vaccination fever and fussiness, especially in children ≥24 weeks of age 4.
- However, the use of acetaminophen as a prophylactic measure is not recommended for all infants receiving DPT vaccination, as it may expose them to possible adverse effects 3, 5.
Management of Fever after Vaccination
- US pediatricians' perception of the severity of fever in infants and their response to infant fever depend on the infant's age, fever severity level, and timing in relation to recent vaccination 6.
- Fever after vaccination is less likely to result in referral to an emergency room or hospital admission compared to general fever 6.
- The American Academy of Pediatrics recommends that parents be educated on how to manage fever after vaccination, including the use of acetaminophen or ibuprofen if necessary.
Incidence of Fever after Vaccination
- A study found that 45.1%, 46.7%, and 51.9% of infants manifested fever within 24 hours after vaccination in different groups, with no significant difference among the groups 5.
- Another study reported that 14% of children randomized to acetaminophen and 22% of those randomized to placebo had a rectal temperature ≥38°C within 32 hours following vaccination 4.