Should you give your child meds before shots?

Especially in the first 5 years of life, children get many immunizations. And some of those vaccines are more likely to cause side effects than others - especially fevers.

So it isn’t surprising that some parents consider giving their children Tylenol/Acetaminophen or Ibuprofen/Motrin/Advil preemptively. But is this a good idea? The answer is a little complicated. Here’s an overview.

(Stay tuned for a separate post on other common side effects from immunizations and ways to manage them!)

Fever and shots

Common side effects of vaccines include body aches, fatigue, injection site reactions, and fussiness.

And, of course, fevers.

Things to know about post-vaccination fever

• Fevers are common. They typically occur within 7 days of receiving the shot, and are more likely with later boosters/doses of a vaccine.  Certain vaccines, such as the MMR and Varicella can cause a fever even a few weeks afterwards.

• Fever does not mean that the immunization gave your child the illness. Parents often get concerned because our kids usually get fevers when they’re sick - so it is natural to assume that a fever means an illness.

  • But the fever is actually an indication of the immune system’s activation in response to an illness: the elevated temps help the cytokine response and immune cascade). Which means a fever after a shot is not only normal, but a good indication that the body is responding appropriately.

The Pediatrician Mom Tip: If a child does not develop a fever, that DOESN’T mean that the vaccine is not working, however.

• In most cases, fever will get better within 1- 3 days. If it persists beyond that time, it is worth discussing with your doctor.

• Fevers after vaccine can be high, and there are a few specific vaccines that can cause febrile seizures. Most of the time, febrile seizures are related not to the specific temperature, but to the rate of rise of the fever. For questions about specific vaccines, I recommend the CHOP website for reliable information.

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Fever-reducers before shots

The truth is, the data is mixed about whether or not this is recommended.

There are some studies in kids that suggest that giving an anti-inflammatory medication (like Tylenol/Paracetamol/Acetaminophen or Ibuprofen) pre-emptively might blunt the immune response to a shot.

In particular, a randomized controlled trial from the Czech Republic (PMID: 19837254) found that antibody levels in kids that received Acetaminophen before their vaccines were significantly lower. Another study (PMID: 24897504) in adults found similarly that antibody levels were lower in a group that received Paracetamol before Hep B vaccines.

In both cases, though, it is unclear whether the degree of blunting of the immune response had any real clinical significance.

Another systematic review of 13 trials (PMID: 25180516) found that although there were significant differences in antibody levels between groups who received medication pre-emptively and those who did not, the levels of antibodies in both groups were still at what would be considered protective levels. That study did find that Acetaminophen before the shot reduced the risk of a fever 24-48h after immunizations in kids… but half the kids in the placebo group (who didn’t receive the medicine) never had a fever anyway.

On the flip side: Another interesting study (PMID: 3059756) found that while medication given before the shot might decrease the antibody levels, if given more than 4 hours afterwards, that effect disappeared.

So, what do I recommend?

I completely understand the parent desire to protect your child from discomfort (and to want to make sure they sleep…), but many children do not have fevers after shots, and handle them fine.

The bottom line: It is fine to treat your child with medication if they seem like they are uncomfortable, or have a fever or pain. But wait and see how they do (and if you can, hold off on giving it until at least 4 hours after the dose).

What about glutathione?

This is a common fear-mongering trope I see online and on social media. “Don’t give your child Acetaminophen because it depletes their Glutathione levels and they will go into liver failure”.

In one sense, this is accurate. Acetaminophen does decrease the level of an anti-oxidant called Glutathione. This is because when it is broken down in the liver, it forms a byproduct that then is removed by Glutathione. So if you have too much Tylenol then you overwhelm the supply of Glutathione and that byproduct builds up.  This can absolutely lead to liver damage.

But the dose makes the poison. This mechanism is relevant when someone has too much Acetaminophen in their system (ie. an overdose or long term chronic use). For purposes of this discussion, or during an acute illness in a child, it is irrelevant - and simply fear-mongering. A few doses will not cause a problem. Just make sure you’re dosing correctly — I have a free download with dosing information in the guide section of this website.

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My hope is that this post reassures you that fever is not the enemy, and actually part of a healthy body’s immune response!

And those vaccines absolutely do help strengthen those little immune systems so they can handle these illnesses if they encounter them!