Reactions to Vaccines in Babies

Mild side effects may occur, but serious allergic reactions are very rare

Vaccinations are critical to preventing disease and are an essential part of your baby's health care. Though some babies can have reactions to vaccines, such as tenderness at the injection site or a fever, these are generally mild and short-lived. A serious allergic reaction is possible, but rare.

A baby receives a vaccination
Bjarte Rettedal / Getty Images

In most babies, the pros of vaccines far outweigh the cons—including possible reactions. If your child has a health concern that would make vaccine inadvisable, your pediatrician will let you know.

This article discusses a baby's common reactions to vaccines and the signs of a serious allergic reaction. It also covers when to seek emergency care and when to avoid or postpone vaccinations.

Common Reactions to Vaccines

It is not unusual for babies to have side effects after getting a vaccination. Most are not all that serious and usually resolve within a day or two. The most common ones include:

  • Tenderness, redness, or swelling at the injection site
  • A slight fever
  • Irritability
  • Crying

Breastfeeding or bottle-feeding after an injection may help calm a fussy baby.

It may help to keep a bandage on the injection site for a few days as a visual reminder that the area may be sore.

Signs of a Serious Reaction

While rare, serious allergic reactions to infant vaccines have been known to occur. If not treated immediately, it could lead to a potentially life-threatening allergic reaction known as anaphylaxis.

Over the course of minutes to hours, the symptoms can worsen as the airways become increasingly constricted, leading to respiratory distress and other serious side effects.

When to Call 911

Call 911 if your baby experiences some or all of the following symptoms after an immunization:

Most cases of anaphylaxis occur within eight hours of getting a shot but can happen in less than 30 minutes. If left untreated, anaphylaxis can lead to unconsciousness, seizures, shock, coma, and even death.

Estimating Risk

Anaphylaxis can occur in response to any medication. While the possibility is worrisome, it should not cause you to avoid vaccinating your child. Research has shown that the risk is extremely low.

A 2016 study from the Centers for Disease Control and Prevention (CDC) reviewed data from the Vaccine Safety Datalink and confirmed that there were just 33 cases of anaphylaxis out of 25,173,965 vaccine doses administered from January 2009 to December 2011.

Based on their findings, the CDC researchers concluded that the risk of vaccine-triggered anaphylaxis is rare for all age groups.

When to Postpone or Avoid a Vaccination

As a general rule, infant immunizations are safe and a vital component of your child's good health. There are certain circumstances in which it may be necessary to skip or delay a shot, however:

  • If an infant has a fever, they shouldn't receive a vaccination until they're completely recovered. It is safe to vaccinate a child with a cold, however.
  • If an infant has had a previous allergic response to a vaccine, it's important to seek expert consultation with an allergist to identify the cause. This can help determine which vaccines are safe or unsafe for use.

Any infant with fever or illness should be evaluated by the doctor before receiving any vaccine.

Frequently Asked Questions

  • How long do babies feel unwell after vaccinations?

    For local reactions, like swelling, pain, and redness, the symptoms may last three to five days. A fever may last one to two days.

  • Can babies be congested after a vaccine?

    Runny nose and nasal congestion are common symptoms for babies after receiving the nasal influenza vaccine.

  • Can babies develop a cough after getting a vaccine?

    It's not a common side effect, but trouble breathing can occur and be a sign of a serious reaction. Seek immediate care if your baby is coughing nonstop and unable to sleep or do normal activities. If your baby develops shortness of breath or a bluish tinge to the skin, call 911.

  • Do babies sleep a lot after vaccinations?

    Some babies do sleep more than usual after vaccinations. This should last about 48 hours after they get their shot.

  • What vaccines is given orally to babies?

    The rotavirus vaccination is given to babies by mouth. Rotavirus is a gastrointestinal virus that causes vomiting and diarrhea that can be so severe it causes dehydration. Side effects of the oral rotavirus vaccine include diarrhea and a mild fever.

Vaccines Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Mom and Baby
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Vaccine Safety FAQs for Parents and Caregivers.

  2. McNeill MM, Weintraub ES, Duffy J. Risk of anaphylaxis after vaccination in children and adults. J Allergy Clin Immunol. 2016 Mar;137(3):868–78. doi:10.1016/j.jaci.2015.07.048

  3. Centers for Disease Control and Prevention. Vaccine recommendations and guidelines of the ACIP: Preventing and managing adverse reactions.

  4. Seattle Children's Hospital. Immunization reactions.

  5. Seattle Children's Hospital. Trouble breathing.

By Stephanie Brown
Stephanie Brown is a parenting writer with experience in the Head Start program and in NAEYC accredited child care centers.