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Why High Fever Temperatures Can Be Deceiving

It was the first night of their Disney vacation when Jennifer and David Kimock, of Yardley, Pennsylvania, awoke to find their 2-year-old son, Andrew, shaking and burning with fever in his portable crib. They decided to give him Tylenol and find a doctor in the morning, but Andrew threw up the medicine. "As we were cleaning it up, he let out this bloodcurdling scream," recalls Jennifer. "He was looking frantically at our bed and clinging to Dave and me. I'd read that kids can hallucinate with high fevers. I was terrified."

The Kimocks called the front desk, which summoned an ambulance. At the hospital, doctors reassured the couple that hallucinations are not unheard of with high fevers (Andrew's was 103.6 F.) and that their son had a simple ear infection and possibly a throat infection. They prescribed an antibiotic. By the next night, Andrew was enjoying dinner with his 5-year-old sister, Rebecca, and the Disney princesses.

Nothing can spike worry in a parent like a child's high fever. But a temperature itself is rarely dangerous, says Adam Pallant, MD, director of the Brown Medical School pediatric residency program at Hasbro Children's Hospital in Providence, Rhode Island. Children can safely tolerate fevers as high as 106 degrees, he says. Moreover, no matter what the reading on the thermometer, a fever simply means your child's immune system is doing its job.

What Fever Means

Most of us have been taught that a body temperature of 98.6 degrees is normal. But this number can actually vary by a degree or so, depending on the child, his activity level, the amount of clothing worn, and time of day. Thus, most doctors define a fever as any rectal temperature of 100.5 degrees or more.

A fever is usually a response to an infection by a virus, but sometimes by bacteria. The body's immune system senses this "invader" and releases chemicals signaling the brain to increase body temperature above normal. Researchers believe this is because most viruses and bacteria have difficulty surviving at higher temperatures. Some scientists speculate that fever may also rev up the body's immune response (though there's no proof that lowering your child's temperature slows recovery). Keep in mind that a fever itself is not an illness, but rather a symptom of an underlying cold or infection.

While most fevers are not a cause for panic, a fever in a newborn needs to be taken seriously. Because babies younger than 2 months can develop serious bacterial infections whose only sign is fever, doctors generally don't take chances.

"If a baby is younger than 2 months old and has a rectal temperature of 100.5 degrees or higher, call your doctor," says David Banner, MD, assistant clinical professor of pediatrics at the University of Pennsylvania Children's Hospital in Philadelphia. Newborns with a fever will typically be tested for bacterial infections, such as meningitis, a urinary tract infection, or pneumonia, and might be admitted to the hospital and given intravenous antibiotics as a precaution until their test results return. Such extreme caution is necessary, explains Dr. Pallant, because infants can encounter bacteria while passing through the birth canal during delivery, leading to meningitis or other infections during their first two months of life.

The good news is that such infections are exceedingly uncommon. Most experiences with newborn fever are like that of Christine Wall's, of East Providence, Rhode Island, who rushed her 5-week-old daughter, Leeanne, to the emergency room at 3 a.m. with a 105.1-degree fever. Doctors performed a spinal tap to rule out bacterial meningitis and gave the baby precautionary antibiotics. "It was one of the most nerve-racking nights of my life," says Wall. But Leeanne turned out to have nothing more than a cold. And a young infant can handle a routine illness, such as a cold, just as well as anyone, says Dr. Pallant.

Once your baby is older than 2 months, fever alone no longer constitutes an emergency. Doctors recommend focusing less on the thermometer reading, even if it's 104 degrees, and more on how your child looks and acts. Is he limp and lethargic or alert and eating? Of course, a fever may cause a certain amount of irritability in itself.

You can lower baby's fever with acetaminophen (Tylenol) or, for babies older than 6 months, ibuprofen (Motrin or Advil). "Once the temperature is down, that's the time to really assess your child," says Andrea Jill Leeds, MD, a pediatrician in Bellmore, New York. "If she's playful and seems more herself, then you know it was the fever making her uncomfortable. But if she's still out of it, listless, or unresponsive, call your doctor -- something more serious may be going on."

When giving fever-reducing medicine, be sure to carefully read dosing instructions. Ibuprofen should not be given to babies younger than 6 months or to children who are vomiting or dehydrated. And never give aspirin to a child because it may cause Reye's syndrome, a potentially fatal liver condition.

For a fever that responds well to medication, and especially if it's accompanied by obvious cold (cough, stuffy nose) or stomach bug symptoms (minor diarrhea), your doctor may advise you to stay home but to call if symptoms worsen or don't improve in a day or two. However, if a fever persists for longer than three days or is your child's only symptom, see your pediatrician. It could be that your baby has a bacterial infection, often an ear infection, which may require an antibiotic.

The best way to get an accurate temperature reading on a child 5 years old or younger is rectally, using a digital thermometer. "A rectal temperature is the only true core body temperature, so parents should get comfortable using this method," says Dr. Leeds. You can position your child as if you were going to change his diaper (on his back with his legs raised) or lay him down on his belly, and then insert a digital thermometer a half inch into his anus and wait for the reading to be completed. If you're worried about hurting your baby, remember that the tip of the thermometer is much smaller than an infant's stool, says Dr. Leeds. Just don't use a mercury thermometer because if it breaks, the liquid mercury that spills out is toxic.

Taking an underarm temperature may be easier, but it's not particularly accurate, says Dr. Leeds, noting that these axillary readings tend to be 1.5 degrees lower than rectal readings.

Parents like ear thermometers because they're fast and easy to use, but they're also not as accurate as rectal readings.

Besides medication, a tepid bath can help to bring down a child's fever, says Dr. Leeds. "But make sure the water is comfortable, not cold, since chills can increase a fever." Never sponge a baby with alcohol, which can be toxic if too much gets absorbed through the skin.

To prevent your infant from getting dehydrated, continue breast- or bottlefeeding. Try not to worry if a sick toddler refuses to eat -- most kids can safely go days without food, says Dr. Banner. But it's crucial that your child drink fluids. Offer frequent sips of water, juice, or (especially if your child is vomiting or has diarrhea) an electrolyte solution such as Pedialyte. If your child won't drink, try ice pops or Jell-O.

Karen Cyr, of Glastonbury, Connecticut, wets a washcloth and lets her daughter suck on it when Miranda, 3, refuses to drink. She's also used a medicine dropper to squeeze small amounts of water into her daughter's mouth.

Although fevers have a way of rattling even the calmest parents, they're rarely cause for alarm. With some care and comfort, most babies bounce back in no time.

Marguerite Lamb is a mother of two in Glastonbury, Connecticut.

Originally published in American Baby magazine, January 2005.

All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.