Q: My 13-year-old has a fever and chills after getting Hepatitis B and Bexsero vaccines. Is this normal and when should we see a doctor?

Medically reviewed by Sang Hyun Ahn, MD

Content edited by Myeongchan Kim, MD

This post is a dramatization of a question and answer session experienced by our actual medical reviewers. Please note that this content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.

Question:

My 13-year-old received their 2nd dose of the Hepatitis B vaccine and their 1st dose of the Bexsero (Meningococcal B) vaccine on Thursday at 2:00 PM. By Friday at 2:00 AM, they developed a fever over 38°C and chills. We are giving them fever reducers, but they are tossing and turning and having a hard time sleeping deeply.

1. I read that vaccine fevers usually drop within 24 to 48 hours. Does this timeframe start from the time of vaccination or the onset of the fever? Also, is it normal for a teenager to have a vaccine fever? This is their first time having one since they were a baby. I also got the Bexsero vaccine but didn't have any fever.

2. Does the Bexsero vaccine frequently cause fever? Can chills be a part of a normal vaccine reaction?

3. In summary, if they still have a high fever by Friday afternoon, should we visit the clinic today, or is it okay to wait until Saturday while continuing to give fever reducers?

Answer:

I understand it can be concerning to see your child develop a fever and chills after their vaccinations.

Evaluating Post-Vaccination Fever

The Bexsero vaccine is well-known for frequently causing localized pain, fever, and chills, even in adolescents and adults. Individual reactions can vary greatly, which explains why your child developed a fever while you did not.

The 24 to 48-hour observation window is calculated from the time of vaccination. Therefore, based on a Thursday 2:00 PM vaccination, the 48-hour mark would be Saturday at 2:00 PM.

What You Should Do Now

* Administer fever reducers (acetaminophen or ibuprofen) as needed for comfort, strictly following the recommended dosage and intervals.

* Dress them in light clothing, maintain a comfortable room temperature, and encourage frequent fluid intake.

* Do not use physical cooling methods (such as wiping them down with lukewarm water), as this is not recommended.

When to Seek Immediate Medical Care

Please bring your child in for an in-person evaluation today if they experience any of the following warning signs:

* A fever of 39°C or higher that does not come down even with fever reducers.

* A stiff neck, severe headache, or repeated vomiting.

* Difficulty breathing or chest pain.

* Altered mental state, confusion, or extreme difficulty waking up.

* No urination for 8 hours or more.

When It Is Safe to Observe at Home

If none of the above warning signs are present and your child is generally stable, you can safely monitor them at home until Saturday afternoon while continuing to manage the fever.

* If the fever persists past Saturday at 2:00 PM (48 hours post-vaccination), please consult your pediatrician.

* If any new symptoms develop (such as a rash, worsening joint pain, or continuous vomiting), seek a medical evaluation on the same day.

In summary, if there are no danger signs, you can manage the symptoms at home with fever reducers and hydration until the 48-hour mark. If the fever continues beyond that point, or if you are ever unsure about their condition, please follow up with a doctor for a proper evaluation.

For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.

https://fevercoach.us