Treating Your Child’s Fever

Few things frighten parents as much as their child suffering from a fever.  These days, fevers are one of the most common reasons that parents contact their pediatrician.  Fever itself is not an illness, but a symptom caused by many different conditions.

Fever is defined as an oral or ear temperature greater than 99.4°F, an under the arm temperature greater than 98.6°F, or a rectal temperature greater than 100.4°F.

A child’s temperature fluctuates throughout the day between 97.1°F and 99.5°F and tends to be slightly higher in the afternoon and evening.

Digital rectal thermometers are the safest and most accurate for infants and young children.  (I do not recommend using mercury glass thermometers because of the potential for accidental exposure to mercury.)  For older children an oral temperature is preferred but under the arm is often close enough.  In my experience, the over the counter ear and forehead thermometers are very inaccurate and often give false readings.  In general, parents should not measure their child’s temperature unless they suspect something is wrong (poor appetite, lethargic, fussy…)

Although many parents fear that a fever will harm their child, it is the underlying cause that may be the real concern.  Technically, a fever is not dangerous in and of itself until it reaches 107.6°F.  Unlike adults, in children a higher temperature does not generally suggest a more serious infection or condition.  Fever is not the enemy.  Since many of the bacteria and viruses that infect humans thrive at 98.6°F, our bodies naturally respond with fever to help us fight these common infections.

If your child is happy, playful, well hydrated and comfortable, I don’t recommend treating their fever.  On the other hand, if your child appears ill, in pain or unable to get comfortable, I would try to relieve their discomfort by bringing down the temperature.  If they improve within 30-45 minutes after an appropriate dose of medicine, it is less likely that they have something serious.  Like other forms of stress, excessive discomfort from fever can negatively affect a child’s immune system and ability to heal.

When treating a fever at home, start by making sure your child is not dressed too warmly.  Keep the house temperature cool but comfortable. Make sure your child is drinking plenty of cool fluids. For mild fevers, you can try giving your child a lukewarm bath.  Never use very cold water or alcohol rubs as this may actually worsen the situation by constricting your child’s blood vessels.

Acetaminophen (Tylenol) and Ibuprofen (Advil or Motrin) are the two medications commonly used to control fever.  Before 6 months of age, Acetaminophen is the only option.  It generally lasts 4-6 hours and should not be given more often to avoid potential liver damage.  After 6 months, I prefer Ibuprofen because it tends to work slightly faster, reduce fever more effectively, last longer (6-8 hours), and it has a safer toxicity profile.  The main side effect, abdominal discomfort, can be avoided by giving it with meals.  Aspirin can cause a life threatening liver disorder called Reye’s Syndrome, and should never be given to children.  Herbal preparations with White Willow Bark (the original source of Aspirin) also should be avoided.

Any fever in an infant less than two months of age is considered a medical emergency, and you should contact your child’s medical provider immediately. If your child has a fever for more than seventy two hours it is also wise to contact your doctor.  

Dosing:  To simplify dosing, manufactures give suggestions based on age and weight but the dose is often too low to be effective. Calculating the optimal dose for Acetaminophen and Ibuprofen is very easy. 

For Acetaminophen (Tylenol)

• Determine your child’s weight in kilograms (kg). You do this by dividing their weight in pounds (lbs.) by 2.2. For example, our daughter weighs 28 lbs., so her weight in kilograms is 28 lbs. ÷ 2.2 = 12.7 kg
• To calculate Acetaminophen (Tylenol) dosing in milligrams (mg), you would then multiply your child’s weight in kg by 15. So, using our example 12.7 kg x 15= 190.5 mg per dose, every 4-6 hours.
• Now, you need to determine what volume in milliliters (ml) to give your child based on the strength/concentration of the product. As of 2015 there is only one concentration for Acetaminophen and it is 160 mg per 5 ml. So, again using our example, to give a dose of 190 mg to a child you would need to divide 190 by 160 and multiply by 5.

190 ÷ 160 x 5 = 5.9. So you would give your child 5.9 ml of Acetaminophen.

For Ibuprofen (Motrin or Advil)

• Determine your child’s weight in kilograms (kg). You do this by dividing their weight in pounds (lbs.) by 2.2. For example, our daughter weighs 28 lbs., so her weight in kilograms is 28 lbs. ÷ 2.2 = 12.7 kg
• To calculate Ibuprofen (Motrin or Advil) dosing in milligrams (mg), you would then multiply your child’s weight in kg by 10. So, using our example 12.7 kg x 10 = 127 mg per dose, every 6-8 hours.
• Now, you need to determine what volume in milliliters (ml) to give your child based on the strength/concentration of the product. As of 2015 there are two concentrations for Ibuprofen and they are 100 mg per 5 ml for Children’s and 100 mg per 2.5 ml for Infant’s (infant ibuprofen is stronger to allow you to give a smaller volume).
• Children’s Strength: So, again using our example, to give a dose of 127 mg to a child using Children’s Strength Ibuprofen, you would need to divide 127 by 100 and multiply by 5.

127 ÷ 100 x 5 = 6.35 ml. So you would give your child 6.35 ml of Children’s Strength Ibuprofen.

• Infant’s Strength: Using or example again for Infant’s Strength Ibuprofen this time, to give a dose of 127 mg to a child using Infant’s, you would need to divide 127 by 100 and multiply by 2.5.

127 ÷ 100 x 2.5 = 3.18 ml. So you would give your child 3.18 ml of Infant’s Strength Ibuprofen.