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Fevers in children: What’s all the fuss about?

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At 7 a.m. on my way to work at Sickkids, I hear the familiar piano riff of my iPhone ring. On the other end is my wife Shelley. Our youngest has woken up with a fever. What to do? Is it okay to give her some Tylenol and ship her off to school? Should she spend the day at home? Does she need to see her doctor? Yes, these things happen with regularity even in a pediatrician's home, and especially it seems when both parents have busy days planned.

What is important for any parent to know about fevers? To start, how can you tell if your child has a fever? The most accurate measurement is as close to your body 'core' as possible; in children that would be rectal. This is neither practical nor necessary unless there are very specific circumstances requiring an accurate reading (for example in the first three months of life).

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Most children will not co-operate with keeping a thermometer under their tongue until four or five years of age. Between three months and five years, the most easily accessible place to take the temp is in the armpit. Not that accurate but good enough for most of us. (High-tech folks may use an ear thermometer; personally I don't think that is necessary.)

What is normal? This varies depending on how close to the body core you are; in the rectum anything up to 38 C; under the armpit anything up to 37.2 C; the ear and mouth are somewhere in between (37.5 C).

What does a fever mean? It basically tells us that your child's immune system is mounting an appropriate response to some sort of attack. In children in the vast majority of cases this would be some sort of viral infection. As my mentor used to tell his patients: The fever is like a burglar alarm, it is not the actual problem (although it can be irritating!) but is alerting you to the presence of something that needs to be dealt with.

How does one sort out what is setting off the alarm? In young children, the accompanying symptoms often provide the clues:

  • A congested or runny nose with cough usually means a viral upper respiratory tract infection, a.k.a. a cold.
  • Vomiting, tummy pains usually followed by diarrhea usually means a viral gastro or stomach flu.
  • Waking up crying in the middle of the night after having a cold for a few days may mean an ear infection.
  • And teething, for the record, doesn’t cause fever, so don’t be blaming it!

So how does a parent decide if they should be worried or not? How sick your child is does not necessarily correlate with the height of the fever. Some very sick children will have no fever, and others with a fever of 40 C may have a relatively harmless case of roseola or other self limited viral illness.

A child who is inconsolable, not interactive, not willing to eat or drink or has difficulty breathing is one who needs to be seen by a health-care provider, regardless of whether they have a fever or not.

In contrast, a child with a fever of 40 C who after a dose of Tylenol is relatively happy, playful and interactive is generally one that can be watched at home over the ensuing 24 hours to see how things evolve.

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In certain circumstances, though, fevers need to be checked out ASAP, especially if your child has problems with their immune system, which includes infants in the first three months whose immunity is only just starting to develop. Also, most viral fevers settle in two to three days, so fevers lasting longer will need attention from a health-care provider.

Should you treat a fever? If your child seems uncomfortable with the fever then there isn't any downside. (Reports that treating fevers may significantly blunt the immune response have not been substantiated.) But if they have a fever and are playing happily without a care, or sleeping peacefully, then there is no advantage in doing so.

If you do decide to treat the fever, how should you do this? Both acetaminophen (Tylenol or Tempra) and ibuprofen (Advil or Motrin) are safe to use and work well in children if given in the correct dose.

Common mistakes made by parents are not calculating the dose by weight (you need to know approximately how much your child weighs – there is a big difference between infants of similar ages), and giving medication more frequently than recommended. This is compounded when parents use more than one product – more is not necessarily better!

Can the fever cause damage to your child? This is a concern voiced by many parents. We have no reason to believe that the fever itself can harm the child. What we do see not infrequently are febrile convulsions, which are seizures triggered by the sudden rise in temperature in susceptible children between six months and six years of age. The good news is that while watching your child have a seizure may be damaging to you (it's extremely scary), these do not cause damage to children and they grow out of them by the age of six years. Children are born with this vulnerability and there is no actual proof that aggressively treating the fever will actually lessen the risk of a seizure anyway.

I hope I have been able to relieve some of the anxiety felt by our somewhat fever phobic culture in North America. Oh yes, and we did decide to give my daughter a dose of Advil; she looked good and the fever settled, so we sent her off to school. As the effect of the medication wore off and she got warmer and crankier, we got a call from the school to come pick her up. She turned out to have a cold.

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Dr. Jeremy Friedman is the chief of paediatric medicine and associate paediatrician-in-chief at Sickkids Hospital in Toronto, and a professor of paediatrics at the University of Toronto. Follow him on Twitter @DrJFriedman

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