Sign In
Boston Public Health Commission Home

Fever in Children

What is a fever?
Fever is an increase in body temperature above its normal temperature.  A person’s normal body temperature changes during the day and is usually lowest in the morning and highest in the late afternoon.  A normal temperature also depends on where it is taken. 
What causes a fever?
It is important to remember that, except in the case of heat stroke, fever itself is not an illness – only a symptom of one.  Fevers help your body fight infection. It can be considered a good sign that the body’s immune system is working and is trying to get rid of the infection.  A fever does not mean that you need an antibiotic.
Will a fever cause harm?
A fever is not usually harmful; however, if your child is less than 3 months of age and has a rectal temperature above 100.3 °F you should call your baby’s doctor right away.  Even a slight fever can be a sign of a serious illness in an infant less then 3 months of age.  With a high fever, some children (usually those under the age of 5) may develop seizures, but this is rarely harmful.
How do I know if my child has a fever?
The only reliable way to know if your child has a fever is to use a thermometer.  Testing a child’s forehead with your hand or lips is not accurate.  If your child feels warm, take his/her temperature using a thermometer every 4 to 6 hours while awake. For information on how to take a temperature, see “Taking a Temperature” fact sheet.
Your child has a fever when the temperature is above: 
100.4 ºF measured rectally (bottom)
99.6 ºF measured orally
99.2 ºF measured in the axillary (under the arm) position
100.5 ºF measured in the ear
How can I help my child feel more comfortable?
There are a number of things that you can do to help your child feel better and bring down the fever slightly. 
  • Dress your child in light, loose clothes.  Do not bundle or swaddle the child. 
  • If your child is resting or sleeping, do not cover him/her with heavy blankets. 
  • Keep your child’s room cool. 
  • Make sure your child gets plenty of fluids.  See “Dehydration” fact sheet. 
  • Make sure your child gets plenty of sleep and stays calm when awake.    
  • A sponge bath in lukewarm water may make your child feel more comfortable. Use only lukewarm water, not cold.  Do not give alcohol baths because the alcohol can be absorbed through the skin and cause health problems.
Can I give my child medicine to bring down a fever?
It is important to remember that not all fevers need to be treated. Never give a child or infant aspirin.  It is associated with Reye’s Syndrome, a serious illness. Fever reducing medication such as acetaminophen (such as Tylenol®) or ibuprofen (such as Motrin® or Advil®) can be given to children to bring down the body temperature, but they do not treat the underlying cause of the fever.
  • Talk with your baby’s healthcare provider before giving any fever reducing medication to a child under three months of age. 
  • Ibuprofen should not be given to a child under 6 months of age. 
  • Call your baby’s healthcare provider right away if your child less than 3 months of age has a rectal temperature above 100.3°F even if he or she appears normal. 
  • Call your child’s healthcare provider if your child older than 3 months of age has a fever greater than 102 °F, if it lasts for more than 3 days, or if he/she is acting differently. 
When giving medicine, be sure to follow the instructions on the package to determine how much medicine to give your child.  If your child is taking medicine to reduce a fever, the temperature should be taken just before the next dose of the medicine is due.  The dose for infant drops may seem small; however, it is important to remember it is very concentrated so never give more than it says on the box for your baby’s age and weight.  Check with your child’s doctor if you are not sure how much medicine to give your baby or child.  For any liquid medicines, do not use a household teaspoon to administer, rather, use the medicine spoon, cup or dropper that comes with the medicine.  Repeat doses as directed, but do not wake a sleeping child to give the medicine, unless directed to do so by your child’s healthcare provider. 
When to call the doctor?
Most fevers can be easily treated at home.  Talk to your healthcare provider if you have questions about your child’s symptoms or fever management.  You should get immediate medical care if your child:
  • Cannot hold down fluids
  • Has trouble breathing, even after the nose is suctioned
  • Turns blue
  • Has trouble swallowing or is drooling saliva
  • Has a seizure
  • Stiff neck or neck pain when bending head forward
  • Severe headache
  • Unusual rash
  • Eyes sensitive to light
  • “Acting sick” even after fever is brought down
  • Any concerns or other unusual symptoms​
Boston Public Health Commission
1010 Massachusetts Ave, 6th Floor, Boston, MA 02118.
Phone:(617) 534-5395 Email: