Tips for common vaccine reactions
Mild vaccine reactions to routine childhood immunizations are common. They often get better on their own but here are some tips to help in the meantime.
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Caveat: I am not talking here about the more serious (rare) side effects that are sometimes seen with vaccines, such as allergic reactions, fainting, Guillain-barre, febrile seizures, myocarditis etc. I’m focusing instead on the mild systemic or local reactions that we see occasionally in the office.
CDC routine vaccine schedule
Especially in the first 5 years of life, children get many immunizations.
For those who want to know, I basically stuck to the CDC schedule for my own children, except that I accelerated MMR #2 and did it at age 3, rather than age 4, to get it out of the way and confer protection earlier.
In my experience as a pediatrician, vaccines at age 4-5 are psychologically more stressful for kids— I wanted to minimize the stress of that 4 year check-up by front-loading whatever I could.
Common reactions
Remember: this article is written to provide education, not medical advice. Nothing can replace a personal assessment from your child’s medical doctor, so if you are concerned, reach out to them!
NOTE: most people do not have side effects from vaccines, and even for those that do, they usually begin within a few days of the shot and get better on their own within a few days as well (PMID: 16871116). These side effects are also more likely to happen with later/subsequent/booster doses of the vaccinations,
Common vaccine side effects can be divided into 2 categories: systemic and local.
Systemic: This includes reactions like fussiness, fevers, chills, body aches, headaches and fatigue.
Local: This includes reactions like redness, swelling, or pain at the injection site.
Delayed reactions are possible with certain vaccines such as MMR and Varicella. These are usually in the form of a fever or a rash, and can occur up to 2-4 weeks after receiving the shot.
Should you give medication such as Tylenol or Ibuprofen before your child gets a shot?
The data is mixed on this, but general guidance says this is not recommended. Read more here.
Specific reactions and things you can try:
Injection site pain/redness/swelling: IF this occurs, it is usually mild. Some children are prone to this (especially if they have very fair skin).
Apply a cool compress to the area for 20 minutes soon after the shot, and then again 2-3 times per day for a few days.
Anti-inflammatory meds as needed for pain
Consider colloidal oatmeal soaks to soothe
Monitor for signs of infection.
The Pediatrician Mom Tip: If you notice redness at your child’s vaccine site, outline the red area with a marker. This provides an objective way to monitor whether it is spreading.
Bleeding: Rarely, an injection site might continue to bleed. Apply pressure using an adhesive compress for several minutes. If the bleeding continues for longer than 20-30 minutes, call your pediatrician.
Fever and chills: Fever in and of itself is not a concern. It means the body is responding appropriately.
Treat the child, not the number. Focus on comfort. Although we don’t recommend pre-emptively giving your child medication (before the shot), if your child is uncomfortable, it is okay to give them a dose of Acetaminophen or Ibuprofen (see the “guide” section of this website for dosing information).
Some children may have a high fever but remain generally playful, comfortable, and hydrated. In those cases, a fever-reducer is not needed. '
Other children may have only a mild fever but appear uncomfortable. Those children would benefit from a fever-reducer, but I would wait until at least 4 hours after the vaccine to give it if you can.
If a fever lasts longer than 2-3 days, occurs in kids under 3 mo or in kids with underlying health problems, or if you have any other concerns, talk to your ped.
Focus on other comfort measures as well: skin-to-skin contact and snuggles, hydration, rest, and yes, screen time.
Fatigue: This is also usually a sign that the immune system is responding correctly
Allow rest as needed
If persistent beyond a few days, or if you're concerned, talk to your ped
Sometimes children sleep poorly because of body aches; consider pain medicine if needed in this case.
Pain: Body aches and headaches, especially, are common after shots.
Focus on comfort measures: snuggling, rest, screentime as needed!
Use pain-reducers as needed
Remember, kids who are fussy, in pain and feeling crummy are less likely to drink --> and dehydration can lead to fussiness and body aches. Push* those fluids!
Loss of appetite: This can happen especially with younger infants after a vaccine, and may be related to generally feeling unwell.
Focus on hydration rather than food intake and watch their urine output. Click here to learn how to assess how hydrated your child is and what to watch for based on their age.
When to call the pediatrician
This is not a comprehensive list. In general, always err on the side of calling your pediatrician if you have any concerns about your child. There is a lot to be said for a parent’s gut instinct, and I promise: your pediatrician would rather you called!
If any side effects are not improving within a few days, or if they are getting worse, call your pediatrician. Other red flags include:
Dehydration (see my post on this)
Persistent fever, or fever in children < 3 months or kids with underlying chronic issues or immunosuppression
Non-stop crying not improving with pain medication
Signs of a severe allergic reaction (wheezing, lip/tongue swelling, difficulty breathing, hives, persistent vomiting, etc).
Looking or acting very sick
Altered mental status (confusion, difficulty arousing)
Redness, warmth, swelling or streaking at injection site that is getting worse
Anything else tickling your spidey sense!!
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