Fever in Infants

Fever is very common in children under 12 months of age, and is usually a sign that the body is fighting an infection.

The normal body temperature is 98.6F, or 37C. Doctors generally say that there is a fever when the temperature is 100.4F (38C) or higher.

The best way to take an infant's temperature is rectally with a digital thermometer (never use a glass mercury thermometer). Taking the temperature under the arm, or using an ear thermometer, is less exact.

If your baby has a fever, this guide can help you think about what might be causing it and help you decide if and when you should call the doctor. Please note that this is not meant to take the place of calling or visiting your doctor. If your child has a chronic illness such as sickle cell anemia, or is being treated for any serious illness, you should not use this guide but instead call your doctor immediately.

Click here to begin.

Fever can sometimes be a sign of a dangerous illness.

Does any of the following describe your baby?

  • He has a high fever (greater than 102 F or 39C).

  • He is very irritable.

  • He is very weak or much sleepier than usual.

  • He has dark red spots on his skin that don't get paler when you press on them.

  • He is having trouble breathing (breathing very quickly, labored breathing, sucking in around his ribs).

  • His skin looks pale or bluish.

  • He is vomiting bloody, black, or green liquid.

  • His stool is bloody or black.

  • He has gone more than six hours without a wet diaper.

  • He is drooling excessively and having a lot of trouble swallowing.

Yes, one of these describes my baby.

No, none of those describe my baby.

To continue reading this article, you must log in.

Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.

  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »

I'd like to receive access to Harvard Health Online for only $4.99 a month.

Sign Me Up

Already a member? Login ».

Disclaimer:

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Sign Up
Harvard Health Publishing Logo

Thanks for visiting. Don't miss your FREE gift.

The Best Diets for Cognitive Fitness, is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School

Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health, plus the latest advances in preventative medicine, diet and exercise, pain relief, blood pressure and cholesterol management, and more.

Harvard Health Publishing Logo

Health Alerts from Harvard Medical School

Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss...from exercises to build a stronger core to advice on treating cataracts. PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.

BONUS! Sign up now and
get a FREE copy of the
Best Diets for Cognitive Fitness

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness.

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness.