The Side Effects Kids Could Experience After the COVID-19 Vaccine

The Pfizer-BioNTech and Moderna COVID-19 vaccines are now available for kids aged 6 months and over, and the Novavax shot is available for those 12 and up. Bivalent booster shots, which protect against the Omicron variant, are available for everyone 6 months and up. But with the long-term benefits of vaccination sometimes comes the short-term discomfort of side effects.

Luckily, clinical trials of the vaccine show no serious side effects in young children eligible for the vaccine. That said, minimal effects in kids and teens are possible. Rest, simple pain-relieving medications, and a bit of sympathy can typically help children bounce back quickly. And side effects, which typically include arm soreness at the injection site, tiredness, and/or an achy feeling, rarely last more than a day or two. 

Here, we share the common side effects reported in kids, what you can expect, and how to help your kids through the worst of it. However, note that some kids report no or only very mild side effects from their shots.

Why Do We Get Side Effects?

Side effects can be common after vaccinations (or any medications), and the COVID-19 vaccine is no different. Vaccines provide a tiny portion of a pathogen to the body so that the immune system learns to recognize it as a threat and build a defense against it.

Jay M. Lieberman, MD, infectious disease specialist, explains that side effects are simply the immune system hard at work. “A lot of the symptoms that we develop after vaccination are not a result of the virus or the vaccine per se—it's our response to it,” says Dr. Lieberman. “It's our immune system responding to that foreign invader, trying to fight it off.”

When the immune system is hard at work building this immunity, it can make your child feel a bit yucky for a few days. Every child will experience side effects differently, but don’t worry if your child experiences no side effects. The vaccine is still working.

“We know from the studies that people who didn't develop side effects were still highly protected against the virus,” explains Dr. Lieberman. “We don't understand why certain people have worse symptoms than others.”

Managing Your Child’s Side Effects 

Side effects experienced by kids from the COVID-19 vaccine are generally mild to moderate and similar in nature to those experienced by adults. They are often described as tiredness, an achy feeling similar to having a mild cold or flu, and arm soreness at the injection site. Typically, side effects can be managed with simple remedies and over-the-counter medication.

Jenna Wheeler, MD, a pediatric critical care physician, reminds parents that these side effects shouldn't last long and their kids will be back in full spirits soon enough. "For the majority of children, these symptoms go away quickly in just a few days," says Dr. Wheeler. In the meantime, she recommends "supportive care," which means rest, hydration, and gentle remedies that can hopefully help kids feel a bit better.

Fatigue and Malaise

Fatigue means feeling tired. And malaise means to feel generally uncomfortable, ill, or miserable. The best remedy for these side effects is rest. If your child doesn’t want to sleep, this might be a good time to just let them relax on the couch with a book or a movie.

Aching Muscles and Joints

An achy body can also be treated with rest. However, every child is different. Some kids may find moving their bodies helps relieve the ache. If your child does need to move, try to keep their activities gentle. "Avoid strenuous activity until symptoms improve," says Dr. Wheeler.

If your child is particularly uncomfortable, simple over-the-counter medications such as acetaminophen or ibuprofen may help make them feel more comfortable. 

Headaches 

Pain in or around the head and neck can make anyone feel irritable, especially kids. Sometimes, a cool washcloth on your child’s forehead or a warm washcloth on their neck can help with a headache. Dimming the lights and keeping screens turned off may also help ease their discomfort. It is important to ensure your child is well hydrated, so encourage regular sips of water. 

If the headache is particularly bothersome, an over-the-counter non-aspirin pain reliever can be used.

Injection Site Soreness

The area around the injection site can be sore, red, or even a little swollen for a few days. This is because of the mild physical injury to the tissue. “We all understand that [if] we get a scratch on the arm we see that over the next days it gets a little red as it heals,” explains Dr. Lieberman. “That’s our immune system. Our body responds with inflammation and it's a way of healing.” 

A cool pack on the site can help to reduce the discomfort of the swelling and pain. The swelling, pain, and redness are typically worse in the first day or two and should get better day by day. If it starts to look worse or begins hurting several days after the vaccine, contact your child’s healthcare provider. While uncommon, a worsening of these symptoms can indicate a possible infection. 

Some people have reported a delayed mild allergic reaction commonly called “COVID arm.” This is a ring-like rash around the injection site that appears several days to more than a week after the injection. This reaction is typically considered harmless but can be irritating and itchy. If you have any concerns, speak with your healthcare provider.

Cold packs may help relieve the itch temporarily. Dr. Lieberman also suggests antihistamines, which may be helpful to reduce any itch. But check with your child's healthcare provider to determine if this would be appropriate.

Chills or Fever

The body typically increases its temperature as a mechanism for fighting off pathogens. Sometimes children will feel chills prior to or during a fever.

For low-grade fevers where your child is relatively comfortable, you can encourage your child to wear lighter clothing, take regular sips of water, and rest.

Fever-reducing medications such as acetaminophen or ibuprofen may be used with the advice of your healthcare provider. You should avoid using aspirin in children for pain or fever.

When to Call the Doctor

If your child's side effects appear to get worse rather than better, speak to your child's healthcare provider. Also, if your child experiences anything different than the expected side effects, it is best to seek medical advice.

"Call your pediatrician or family doctor if you have any concerns about your child’s symptoms," advises Dr. Wheeler. "If your child has any complaints of chest pain, shortness of breath, or fluttering/pounding sensation of the heart it is very important to seek medical care."

A Word From Verywell

It is hard to watch your child in pain and discomfort after a vaccine. Remember that you know your child better than anyone else. So if you are concerned at any point, contact your child’s doctor. 

The good news is that side effects should only last a few days. It is important to complete your child's vaccination schedule despite these side effects. Full immunity against COVID-19 is not achieved until two weeks after the second dose of the Pfizer-BioNTech and Moderna vaccines, followed by booster shots as recommended.

Bivalent boosters are available for everyone 6 months old and up, but whether kids 4 years old and under should get them depends on which vaccine they got for their primary series and when. Everyone age 5 and up can get a booster as long as it has been at least two months since their last shot.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.