Fever After Vaccination: What's Normal and What to Watch For
Reviewed by Dr Abhas Gupta, MBBS, MD, DNB (Paediatrics), PDCC (Paediatric Rheumatology) • About Dr Abhas Gupta (Bio) (3 min read)
Yes — mild fever after vaccination is common, and it usually settles within a day or two. It is a sign the immune system is responding.
Key Takeaways
- Mild fever after vaccination is common and usually settles within a day or two as a sign the immune system is responding.
- Fever does not mean your child has caught an illness or that the vaccine has failed.
- With most vaccines, fever begins within about a day; with some live vaccines, a mild fever or rash can appear about a week later.
- Seek immediate emergency care for difficulty breathing, facial swelling, seizures, or unresponsiveness, and consult your pediatrician whenever you are worried.
Why does vaccination cause fever?
A vaccine works by showing your child's immune system a harmless version or piece of a germ, so the body learns to recognise it. Fever is part of that learning process. Check our full guide to the vaccination schedule for the first year to plan upcoming protection dates.
It does not mean your child has caught an illness from the vaccine, and it does not mean the vaccine has harmed your child.
It also does not mean the vaccine failed. Many children have no fever at all after vaccination and are just as well protected.
Some vaccines cause fever later, not straight away
With most vaccines, if fever happens, it happens soon after the injection.
A few vaccines work differently. With some live vaccines, such as measles-containing vaccines, a mild fever or rash can appear several days later — often around a week afterwards. Parents are frequently caught off guard by this, because the vaccination already felt like old news. Protection continues as children grow; learn what comes next in our guide on vaccinations after the first year.
If a fever appears several days after vaccination, it is still worth mentioning to your pediatrician, because it may be unrelated to the vaccine and may need looking at on its own.
When should I talk to a pediatrician?
Trust yourself. You know your child better than any chart does, and no article can examine your baby. If temperature rises persist, consult our pediatric rules on fever management in babies for safe dosage and comfort measures.
- Your baby is very young and has any fever
- Fever lasts longer than a couple of days
- Your child is crying inconsolably and cannot be settled
- Your child is unusually drowsy or difficult to wake
- You are worried — for any reason at all
Frequently Asked Questions
How long does fever after vaccination last?
In most children it settles within a day or two. If it continues beyond that, or your child seems unwell in other ways, speak with your pediatrician.
Should I give medicine before the vaccination to prevent fever?
Giving fever medicine routinely before a vaccination is not generally advised. Ask your pediatrician what is appropriate for your child rather than giving anything in advance.
Does fever mean the vaccine is working?
Not exactly. Fever shows the immune system is responding, but many children have no fever at all and are still fully protected. The absence of fever is not a reason to worry.
My child had fever after the last dose. Should we skip the next one?
A mild fever after a previous dose is not usually a reason to skip future vaccinations. Tell your pediatrician what happened so it can be recorded and considered before the next dose.
The injection site is red and swollen. Is that a problem?
Some redness, swelling and tenderness where the injection was given is common and usually settles on its own. If the swelling is spreading, the area becomes very painful, or your child seems unwell, contact your pediatrician.