Is this a normal fever after vaccines?
Some babies have a low-grade fever after first vaccines, but the exact temperature matters. In a young infant, even a fever that seems mild should be taken seriously.
Fever After Vaccines in Babies Under 3 Months
If your newborn, 8-week-old, or 2- to 3-month-old has a fever after shots, get clear next steps based on your baby’s age, temperature, and symptoms.
About 3–5 minutesPrivate assessmentNo long answers
About this assessment
Answer a few questions for guidance specific to fever after immunizations in a young infant
We’ll help you understand what temperature changes can be expected after first vaccines, when to monitor at home, and when to call your doctor promptly.
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Why this matters in babies under 3 months
A mild temperature increase can happen after routine immunizations, including 2-month vaccines. But in babies under 3 months, any fever needs extra attention because young infants can get sick quickly and often need a clinician’s guidance sooner than older babies. This page is designed for parents wondering what to do about baby fever after vaccines under 3 months, including newborn fever after immunizations and fever after shots in a 2 month old baby.
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What parents often want to know right away
What temperature counts as a fever?
For babies under 3 months, a rectal temperature of 100.4°F or higher is generally considered a fever and is a common threshold for calling a doctor.
What should I do next?
The right next step depends on your baby’s highest temperature, age in weeks, how long the fever has lasted, and whether there are other symptoms like poor feeding, unusual sleepiness, or trouble breathing.
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When to contact a doctor promptly
Temperature of 100.4°F or higher
If your baby is under 3 months and has a temperature at or above 100.4°F, contact your pediatrician or on-call clinician for advice, even if the fever started after vaccines.
Above 102.1°F or rising quickly
A higher fever after 2 month vaccines may need more urgent review, especially if your baby seems uncomfortable, difficult to wake, or is feeding poorly.
Any concerning symptoms
Call right away if your infant has trouble breathing, a weak cry, fewer wet diapers, vomiting, a seizure, bluish color, or is hard to console or unusually floppy.
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What information helps you get personalized guidance
Your baby’s exact age
There is a difference between a newborn fever after immunizations and a fever in a 3 month old after vaccines. Age helps determine how cautious to be.
How the temperature was taken
Rectal temperatures are the most accurate for young infants. Knowing whether the reading was rectal, forehead, ear, or armpit helps interpret the number.
How your baby is acting
Feeding, alertness, wet diapers, breathing, and comfort level are just as important as the number on the thermometer when deciding what to do.
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Frequently asked questions
Is fever after shots normal in a 2 month old baby?
A mild fever can happen after routine vaccines, but in babies under 3 months, any fever should be taken seriously. If your baby’s temperature is 100.4°F or higher, contact your doctor for guidance.
What should I do for fever after 2 month vaccines?
Check your baby’s temperature carefully, note how it was taken, watch feeding and alertness, and contact your pediatrician if the temperature is 100.4°F or higher or if your baby seems unwell. Young infants often need earlier medical advice than older babies.
When should I call the doctor for fever after vaccines in my baby?
Call if your baby is under 3 months and has a temperature of 100.4°F or higher, if the fever is above 102.1°F, or if there are symptoms like poor feeding, unusual sleepiness, breathing trouble, vomiting, or fewer wet diapers.
Can a newborn have fever after immunizations?
Yes, a temperature increase can occur after immunizations, but fever in a newborn or very young infant always deserves prompt medical guidance. Age under 3 months changes how fever is evaluated.
What is a normal temperature after vaccines in an 8 week old baby?
Some babies may run slightly warm after vaccines, but a rectal temperature of 100.4°F or higher is generally considered a fever in an 8 week old. Because your baby is under 3 months, it’s best to contact your doctor if that threshold is reached.
Personalized assessment
Get guidance for your baby’s fever after vaccines
Answer a few questions to get an assessment tailored to babies under 3 months, including what temperatures may need a doctor call and what symptoms should not wait.