Allergic Reactions to a Baby Vaccination

A baby receives a vaccination by a doctor in an office while the mother holds the baby

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Babies receive numerous vaccinations during their first four months of life. While these injections can often make parents squeamish and children weepy, the practice has nearly erased many childhood diseases which were once considered deadly.

Despite myths and misconceptions about their "dangers," immunizations are nothing less than essential to keeping your child healthy and out of harm's way. That's to say that vaccinations are not without side effects.

Knowing which are normal and which are not can help you decide when to take action in the unlikely event your child have an adverse reaction.

Common Side Effects

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 include:

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

Pediatricians will sometimes recommend that you give your baby a dose of Tylenol (acetaminophen) just before or immediately after the shot. Breast- or bottle-feeding after an injection can also help calm a fussy baby.

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 inflammatory response known as anaphylaxis.

The early signs of anaphylaxis in infants are often subtle and easily missed. The most telling may be a persistent cough, usually accompanied by crying and a mild fever. Over the course of minutes and hours, the symptoms can worsen as the airways become increasingly constricted, leading to respiratory distress and other serious side effects.

Call 911 or rush to your nearest emergency room if your baby has been immunized and experiences some or all of the following symptoms:

  • Persistent coughing
  • Wheezing or shortness breath
  • High fever
  • Constant crying
  • Facial swelling
  • Hives
  • Paleness
  • Weakness
  • Fast heartbeat
  • Dizziness or fainting
  • A bluish tinge to the baby's skin (cyanosis)
  • Vomiting
  • Extreme irritability

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

Estimating Risk

One 2012 review of pediatric emergency room admissions over a five-year period estimated that the risk of immunization-related allergy in children is just over one percent. Of the cases involved, none were considered serious. All were associated with the measles, mumps, and rubella (MMR) vaccine and believe caused by an egg allergy. (Both MMR and flu vaccines contain a small amount of egg protein).

Another 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. Some babies, however, may need to skip or delay their shots under certain conditions:

  • Any infant with a cold, fever or other illness should have any vaccination postponed until completely recovered.
  • An infant who has had a previous allergic response to a vaccine should not avoid vaccinations but rather seek expert consultation to identify the cause. This can help determine which vaccines are safe or unsafe for use.

Vaccines Doctor Discussion Guide

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

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Article Sources

  • Cronin A.; Scorr, J.; Russel, S. "A review of a paediatric emergency department vaccination programme for patients at risk of allergy/anaphylaxis." Acta Paediat. 2012;101(9):941-5. doi:10.1111/j.1651-2227.2012.02737.x.

  • MacNeil, M.; Weintraub, E.; Duffy, J. et al. "Risk of anaphylaxis after vaccination in children and adults." J Allergy Clin Immunol. 2016;137(3):868-78. doi:10.1016/jaci.2015.07.048.