• 3 weeks ago

Fever After Vaccination in Children: How Long Does It Last and What Should You Do?

Is Fever After Vaccination Normal?

Yes. Vaccines activate the immune system to prepare the body to fight real infections. This immune activation may cause mild fever, especially after vaccines that contain live viruses such as measles or MMR (measles-mumps-rubella).

Which Vaccines Commonly Cause Fever?

Some vaccines are more likely to trigger fever:

Vaccine

Likelihood of Fever

Onset Timing

BCG

Rare

2–4 weeks later (may include lymph node swelling)

DTaP-IPV-Hib (combined vaccine)

Common

Within 6–48 hours

Pneumococcal

Moderate

Within 24 hours

MMR (Measles-Mumps-Rubella)

Common

5–12 days later

Varicella (Chickenpox)

Moderate

About 1 week later

Hepatitis A/B

Rare

Within 24 hours

How Long Does Post-Vaccine Fever Last?

  • Typical duration: Starts within 1–2 days and resolves within 48 hours.
  • Live virus vaccines: May cause delayed fever (5–12 days after injection), lasting 3–5 days.
  • Low-grade fever (<38°C or 100.4°F): Usually requires no treatment.
  • High fever (≥39°C or 102.2°F) or fever lasting over 3 days should be evaluated by a physician.

What to Do: Managing Fever After Vaccination

1. Assess Your Child’s General Condition

If your child is alert, feeding well, and active despite the fever, there is usually no cause for concern.

2. Encourage Fluid Intake

Fever increases fluid loss. Breastfeed more often or offer water and fluids to older children.

3. Dress Lightly

Avoid overdressing. Use breathable, cotton clothing to keep your child comfortable.

4. Lukewarm Sponge Baths

For fevers above 38.5°C (101.3°F), gently wipe the forehead, underarms, and groin with lukewarm water.

5. Use Fever Reducers if Needed

With medical advice, use acetaminophen (paracetamol) in the correct dose. Ibuprofen is not recommended for babies under 6 months.

When Should You Call a Doctor?

Seek medical attention if:

  • Fever is above 39°C (102.2°F)
  • Fever lasts longer than 72 hours
  • Accompanied by vomiting, diarrhea, or rash
  • Child refuses to feed or is difficult to wake
  • Seizures (febrile convulsions) occur
  • The injection site becomes very swollen, red, or develops a lump

Other Common Mild Side Effects of Vaccines

  • Pain, redness, or swelling at the injection site
  • Mild fussiness or irritability
  • Loss of appetite
  • Occasional vomiting or loose stools (rare)

These effects are typically short-lived and resolve on their own.

What Not to Do When Treating a Fever

  • Do not use alcohol rubs
  • Avoid cold baths (they may cause shivering)
  • Do not give over-the-counter medication without a prescription
  • Don’t overdress or tightly swaddle the child