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Fever in Children – Frequently Asked Questions

Fever is a very common reason for children to be brought in for medical assessment.  Below are answers to some of the most common questions that caregivers have with respect to fever.

What causes fever? 

Fever is the body’s natural response to infection. Some infections are caused by bacteria.  Examples include strep throat, pneumonia, bladder and kidney infections, cellulitis (infection of the skin), and meningitis. Other infections are caused by viruses.  The common cold, laryngitis, croup, and bronchitis are all viral infections.  In fact, viral infections are by far the most common reason for fever in a child.

How can I tell if my child has a fever?

Placing the back of your hand on the child’s forehead is one of the easiest ways to see if a child has a fever.  Studies have shown that this tried and true method is surprisingly accurate at determining if a child has a fever or not.  Most decisions about what to do with a fever are not actually related to the exact temperature – they are more dependent on how the child looks and if they have any other symptoms.  As a result, this method is often all you need to use to determine if your child has a fever.

If it is important to measure the degree of fever, some alternatives are listed below:

Once a child reaches the age of 5 or 6, they can usually co-operate enough to obtain an oral temperature.  This is done by placing a thermometer under the tongue and having the child close his or her lips around it.  A temperature greater than or equal to 37.5 degrees Celsius (99.5 degrees Fahrenheit) is considered a fever.

Alternatively, tympanic or ear thermometers can be used.  A temperature of greater than or equal to 37.5 degrees Celsius (99.5 degrees Fahrenheit) is once again considered a fever.  It should be noted that the ear thermometers are NOT accurate in children under the age of 2, and should not be used in this age group.

Checking the temperature under the armpit is an alternative method.  This method is easier but unfortunately is not particularly accurate.  A temperature over 37.0 degrees Celsius (98.7 degrees Fahrenheit) is considered a fever. 

A rectal temperature is taken by inserting a lubricated thermometer probe in to the rectum.  This is the most accurate way to measure a temperature, and is usually used by the medical team when assessing infants less than 3 months with a possible fever.  A rectal temperature of 38 degrees Celsius (100.4 degrees Fahrenheit) is considered a fever. 

How high of a fever is considered dangerous?

There is no set temperature at which fever is considered dangerous.  What is most important is not how high the fever is, but rather how your child looks and acts with the fever.   Particular signs that a child needs medical assessment include:

  • Fever in an infant less than 3 months old.  Infants do not have a mature enough immune system to fight infection properly, and need to be seen right away with fever.

  • Fever associated with a lethargic child.  Lethargy refers to a child who not interested in his or her surroundings, is excessively sleepy or drowsy, and simply looks very unwell. 

  • Fever that is lasting for more than 4 days

  • Fever associated with severe headache and/or neck stiffness

      If you are suspicious there is serious infection causing the fever.  Sometimes you are just worried that there is something more serious going on, and parental concern is a good reason for a child to be seen.  In particular, first time parents can have a hard time telling if a fever is caused by something serious, and sometimes need assistance in sorting this out.  This is normal!

Reassuring signs in a child with a fever include:

  • A child who is still active and playful

  • A child who is eating and drinking normally

How can I treat fever?

It is not always necessary to treat a fever.  In fact, it is believed that fever assists the body’s immune system in fighting infection. 

Having said this, giving a child medication for fever can often help with relieving muscle aches or pain, improving the child’s mood, and allowing the parents some much needed sleep!

Acetaminophen (also known as Tylenol, Tempra) is the most commonly used medication to treat fever. Ibuprofen (Children’s Motrin, Children’s Advil) is also used commonly, particularly in children above the age of 2. Both of these medications work well for fever.  We find that children are often underdosed when dosed according to the standard dosing tables found on the medication bottles. 

Children’s Dosing for Acetaminophen
(also known as Tylenol and Tempra) 

This dosing chart is based on weight, not age, and therefore will provide a more accurate dose of acetaminophen for your child.  Acetaminophen can be used up to every 4 hours as needed.

Weight(Pounds)

Weight(kilograms)

Dosage(15mg/kg)

Infant Drops(80 mg/mL)

Children’s Suspension
(160 mg/ 5 ml)

Children’s Chewable Tablets
(80 mg)

Junior Strength Tablets
(160 mg)

10

4.5

60

0.75 mL

2 mL

 

 

15

7

100

1.25 mL

3.25 mL

 

 

20

9

120

1.5 mL

4 mL

1.5 tabs

 

25

11

160

2 mL

5 mL

2 tabs

1 tab

30

13.5

200

2.5 mL

6.25 mL

2.5 tabs

 

35

15

240

3 mL

7.5 mL

3 tabs

1.5 tabs

40

18

280

3.5 mL

8.75 mL

3.5 tabs

 

45

20

300

4 mL

10 mL

4 tabs

2 tabs

50

23

345

 

11 mL

4.5 tabs

 

Further information on medication use can be obtained from your medical team or pharmacist.

Does my child need antibiotics?

It is worth noting again that most illnesses that cause fever in children are viral and get better on their own.  This is in particular true in the child who has undergone the routine set of immunizations (vaccinations), which are very effective in preventing many bacterial illnesses. 

As infections caused by viruses do not respond to antibiotics, and as antibiotics have the potential for harmful side effects, antibiotics are not used for viral infections.

Ear Infections are a common reason for a visit to the doctor.  They can be caused by a virus or a bacteria.  There is now a large and convincing body of evidence that suggests that most ear infections in children over the age of 2 resolve on their own, without treatment with antibiotics.  In this age group, we now use antibiotic treatment only for children who have persisting ear pain and problems for more than 2 days.

Certain specific illnesses are bacterial, and do benefit from antibiotic treatment.  These include:

Strep Throat – usually seen in children greater than 2 years old;  presents with fever, sore throat, swollen glands.  Sore throat and fever can also be caused by a viral infection - in particular an associated cough and runny nose would suggest more likely a viral cause.

Pneumonia – children have fever, cough, rapid breathing, and/or difficulty breathing.  Many children with a fever, cough and runny nose have a viral infection in the chest – a chest x-ray is sometimes ordered to help distinguish a pneumonia requiring antibiotics from a “bronchitis”, which does not.

Cellulitis – infection of the skin causing a spreading redness or red streaking on the skin. 

Urinary Tract Infection (UTI) – Older children may complain of burning or irritation on urinating, back pain, as well as fever.  Nausea and vomiting can also be a part of a UTI.  In younger children and infants, the diagnosis of UTI can be difficult, and it is one of the things that physicians will check for in a young child with a fever without any other obvious symptoms.

Meningitis or Blood Infection – Both of these illnesses are quite rare, but are very serious. The most common thing associated with these diseases is simply that the child looks very unwell.  Lethargy, drowsiness, severe headache, neck stiffness, and a rash that does not fade under pressure from a finger are all signs of a potentially serious illness.  The new Ontario immunization schedule has immunizations specifically directed at reducing children’s risk of developing these illnesses.

The above information is a brief overview of some of the commonly asked questions with respect to fever.  It is meant to give some general advice on the topic, and shouldn’t replace a visit to the doctor if you have any concerns about your child. 

Many thanks to Dr. Amit Shah, Emergency Physician at STEGH for preparing this article: Fever In Children.