Recognizing and responding to infant fevers

Fever in an infant under 3 months old is cause for concern. Fever in this age group can be a sign of a serious bacterial infection that requires urgent medical treatment.

While you don't have to check the temperature of a healthy-looking infant, it's vital to check your child's temperature if there are signs of illness, or if you believe your child may have a fever.

How to tell if your infant is sick

Determining if an infant is ill can be difficult, but signs can include:

• Appearing to have pale or yellow skin
• Breathing quicker or harder than usual
• Crying and fussing even after efforts to comfort them
• Developing a new skin rash
• Seeming weaker and more tired than usual or hard to awaken
• Having a cough
• Feeding poorly
• Feeling warm to the touch
• Vomiting beyond the normal spitting up

What is a fever?

A fever is a single temperature reading of 100.4 degrees Fahrenheit or greater. However, not all methods of taking an infant's temperature are accurate.

Oral and temporal, or forehead, thermometers aren't recommended for infants under 3 months old. Tympanic, or ear, thermometers aren't recommended until infants are 6 months old.

How do I check a rectal temperature?

A rectal temperature is a quick, easy and accurate way to measure an infant’s temperature. To take a rectal temperature, you need a digital multiuse thermometer, cool water and some lubricant, such as petroleum jelly.

Start by cleaning the end of the thermometer with cool water. Never use warm water because it may affect the reading. Next, place a small amount of lubricant on the end of the thermometer. Place your child on his or her stomach with your hand just above the child's bottom, or on the child's back and raise the legs to the chest. Place the thermometer end 1/2 to 1 inch into the anal opening, and hold it loosely with two fingers. Keep the thermometer in place until it beeps, then remove it. Your child has a fever if the thermometer reads 100.4 degrees Fahrenheit or greater.

My child has a fever. What do I do next?

If your child has a fever, the next step is to take your infant to the nearest emergency department. If there's a serious illness causing your child's fever, quick diagnosis and treatment will help your child recover sooner.

In the emergency department, the medical team will perform a physical exam and run a series of tests to identify the cause of your child's fevers. Some causes can be serious.

Tests may include:

• Blood tests to look for blood infections and signs of infection elsewhere
• Chest X-ray to look for lung infections
• Lumbar puncture to look for meningitis
• Urine tests to look for urine or kidney infections

An infant 1 month old or younger who has a fever likely will have to spend some time in the hospital until the cause of the fever is known and properly managed. Remember, fevers in infants 3 months old and younger are a big deal. Make sure you're checking a rectal temperature. If the temperature is 100.4 degrees Fahrenheit or greater, your child needs to be seen as soon as possible.

Seth Gregory, M.D., is a pediatrician in Red Wing, Minnesota.