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Acetaminophen’s effects on vaccines

Some people believe taking an over-the-counter fever reducer before a vaccine disrupts the body’s immune response. A pediatric nurse practitioner provides some insight
Vaccines_Acetaminophen_immune response_A nurse administers a vaccine on a patient's shoulder

No one enjoys getting vaccines, but most of us do it anyway. “Vaccines are important for keeping yourself, your children and those around you healthy,” said Katie Hepfer, DNP, C-PNP, clinical assistant professor at the Texas A&M College of Nursing. “Most health care providers know immunization schedules can be overwhelming to parents of young children. However, it is important to keep yourself and your children up-to-date on vaccinations.”

That advice leaves many parents—and even adults going to get the shot for themselves—wondering if there is a way to make it easier.

What is a vaccine?

Most vaccines are made from small amounts of a weak or dead agent that resembles a disease-causing germ, bacteria or virus. “The amount and strength of the disease within a vaccine is so small that it won’t give you the disease. Instead, it will build your immunity against the disease,” Hepfer said. “Unlike most medicines, a vaccine does not treat or cure, but actually prevents illness by stimulating your immune system to produce antibodies against the disease or illness.”

Although there are also new emerging vaccine technologies, all vaccines serve the same purpose: to get your body’s immune system familiar with that disease so it can build a defense and keep you healthy.

Common vaccine side effects versus a reaction to a vaccine

“Just like how most medications have side effects, vaccines also have varying levels of side effects,” Hepfer said. “For the most part, vaccine side effects are minor and temporary.” Unless your health care provider recommends against a vaccine for you or your child for a health reason, the side effects are not big enough to warrant skipping a vaccine.

The most common side effects from a vaccination are pain, swelling and redness at the injection site. You or your children may also notice a mild fever as well as general soreness on the arm or leg of the injection.

“There is a difference between a common side effect and an allergic reaction to a vaccination,” Hepfer said. “An allergic reaction may be a rash, difficulty breathing or even something more severe. If that happens, you need to contact your health care provider. However, an elevated temperature is generally nothing to be concerned about.”

Hepfer notes an elevated temperature after a vaccination is actually a good thing. It means your immune response is working.

Does acetaminophen impact the immune response?

Often, people elect to take an over-the-counter pain reliever, or give one to their children, prior to vaccines to help with the side effects. “Remember a vaccination can cause injection site soreness and elevated temperature afterwards,” Hepfer said. “Acetaminophen can both relieve pain and reduce fever, but always speak with your pediatrician first to review dosage.”

The discussion about acetaminophen’s impact on immunity comes with the fever-reducing effect. Typically, fevers are a sign your body is working to kill a virus. As a result, many people worry an over-the-counter drug that reduces fevers will impact how well your body fights the viral agents from a vaccine.

Hepfer said the jury is still out on this. “While the administration of acetaminophen has been commonplace after childhood immunizations for fever and/or pain at the injection site, several newer studies question whether acetaminophen makes vaccines slightly less effective,” Hepfer said. “While acetaminophen is not contraindicated, the American Academy of Pediatrics notes that ‘some pediatricians are no longer recommending it’ for prophylactic use against vaccine side effects.”

A tip to make getting a shot easier

Getting immunized can be a point of anxiety for both adults and children. Luckily, Hepfer gave some simple advice applicable to both adults and children to overcome the fear. She recommends distraction as well as talking with the child and preparing them for what to expect in advance. “If a child is getting a shot, hold them in a comforting way or give them a toy or distraction item,” Hepfer said. For older children, she recommends a game on your phone or listening to music. “Do not underestimate the power of distraction.”

This story was originally published on August 20, 2019 and has been updated for accuracy.

Media contact: Dee Dee Grays,, 979.436.0611

Mary Leigh Meyer

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