The influenza vaccine is generally safe and effective for most children. Like with any vaccine or medication, there is a possibility for side effects to occur in some children who receive the flu shot. Typically, these side effects are mild and go away on their own within a few days. Some of the most common side effects seen in children after receiving the influenza vaccine include:
Soreness, redness or swelling at the injection site: This is one of the most frequently reported side effects. The area where the shot was given may be mildly painful, tender, red or swollen. This usually disappears within a couple days. While uncommon, a small bruise may also develop at the injection site.
Fever: A low grade fever of up to 100 degrees Fahrenheit is not uncommon after getting the flu shot, occurring in about 1 out of every 10 children. The fever usually comes on suddenly about 6-12 hours after vaccination and typically lasts 1-2 days. It is generally not serious and can be treated with over-the-counter fever reducers like acetaminophen or ibuprofen if needed for comfort.
Body aches: Some children may experience mild body aches or muscle soreness after the vaccination that goes away on its own after a day or two. This is especially common if the child has a fever as well.
Fatigue: Feeling tired and lacking energy for a day is a common side effect in children post-vaccination. This is usually not severe and resolves fully after resting.
Headache: A minor, dull headache may trouble some children in the hours or day after getting the flu shot. It is typically mild and goes away with standard treatment like acetaminophen.
Stomach upset: On rare occasions, nausea or diarrhea may occur in children following influenza immunization. This is usually transient, lasting less than a day.
While rare, more severe side effects in children have been reported after influenza vaccination. These include:
Allergic reaction: True allergic reactions to the flu shot are very uncommon, occurring in approximately 1 in 1 million doses. Symptoms of a potential allergic reaction may include hives, wheezing or difficulty breathing that starts several minutes to a few hours after getting vaccinated. This would constitute a medical emergency requiring immediate treatment and monitoring.
Guillain-Barré syndrome (GBS): This is a rare neurological disorder in which the body’s immune system attacks the nerves, causing muscle weakness or even paralysis. It has been reported to be associated with influenza vaccines in about 1 in 1 million vaccinated people. Recovery often takes several months.
Severe fevers: On rare occasions, children have experienced high fevers of 103 degrees Fahrenheit or higher in the days following immunization. This type of fever requires medical evaluation to check for any complications. Most fevers subside with treatment and do not lead to further issues however.
As a parent or caregiver, it’s important to monitor your child for any concerning or unusual symptoms after vaccination and report them promptly to your pediatrician. The vast majority of side effects from the flu shot are mild, temporary, and not cause for alarm. Most experts agree that influenza vaccines provide important protection against illness for children and the benefits vastly outweigh potential risks in almost all cases. Proper screening for allergies or other precautions may be taken by healthcare providers when vaccinating children at higher risk for adverse events. With close post-vaccination surveillance, it is generally safe for the majority of children to receive an annual flu shot.
As the immune response can vary in each individual child, side effects may occur at different levels of severity even for the same vaccine. Factors such as overall health status, previous vaccination history and age can influence potential side effect risk as well. While uncommon, some children may experience no side effects whatsoever after flu immunization. Healthcare providers should thoroughly review the risks and benefits of vaccination prior to administration and discuss what to expect with parents. With appropriate post-vaccination care and monitoring, most discomfort is mild, resolves swiftly, and leaves children fully protected from seasonal influenza for the duration of the immunity period. The influenza vaccine provides substantial protection and low risk to children when utilized as recommended.