You can't take chances when your toddler or child has a fever, but you shouldn't panic either. We'll explain what to look for so you can stay calm—and help her feel better fast.

By Leslie Gross Klaff and Nicole Harris

We've all been there: You're awakened in the middle of the night by the pained cries of your young child, and you notice that her forehead is hot to the touch. You take her temperature, and the reading sends your heart racing. Your first instinct is to speed-dial the doctor. But in most cases here's what experts say you should do instead: Take a deep breath and relax.

Of course, that's easier said than done. Many parents have "fever phobia"—a tendency to freak out when their child's body temperature spikes. As many as 30 percent of pediatric acute-care visits are related to fever, according to a study published in Pediatrics in Review. "A lot of parents think a fever is really dangerous," says Robert W. Steele, M.D., a pediatrician at St. John's Children's Hospital, in Springfield, Missouri. "But the vast majority of the time it's nothing serious."

· RELATED: 5 Things to Know About Fevers and How to Handle Them, From a Pediatrician Parent

In a way, a fever is a good thing: It means your child's immune system is doing its job by fighting an underlying cold or another infection, says Michael Devon, M.D., a pediatrician in private practice near Philadelphia. The brain commands the body's temperature to rise, which in turn directs the white blood cells to attack and destroy invading viruses and bacteria. Amazingly, healthy kids of all ages usually can tolerate a fever of up to 106F with no complications. Chances are your child's temperature will never approach that scary number, but be prepared: It's almost inevitable that sometime during his first three years his temperature will climb into the triple digits.

Should I Visit the Doctor?

Most of the bugs that cause a fever—such as a cold, the flu, a stomach virus—aren't dangerous and are treatable at home. But as a parent, what you should do about a fever depends largely on your child's age and the temperature reading.

Less than 3 months old: Anything above 100.4F warrants a quick call to the doctor. Because an infant's immune system isn't fully developed, she's vulnerable to potentially life-threatening infections like bacterial meningitis and pneumonia, and an elevated body temperature is often the only symptom.

Between 3 and 6 months old: Your child needs to be examined by his pediatrician once his fever hits 101F, says Steven Shelov, M.D., a Parents advisor and the editor-in-chief of American Academy of Pediatrics' Caring for Your Baby and Young Child.

Older than 6 months: You can safely wait to contact your doctor until her temperature rises to 103F, with one important exception. Phone right away if her fever hits 102F or above and she has two or more of these symptoms: a cough, a sore throat, a runny or stuffy nose, body aches, headaches, chills, fatigue, and diarrhea. These classic H1N1 flu symptoms (which are strikingly similar to those for seasonal influenza) tend to occur within 24 hours of the onset of a fever, and your pediatrician might recommend that she take the antiviral drug Tamiflu to reduce the severity and duration of her symptoms.

· RELATED: Signs of Fever in Babies and Children

Since fever is a signal from the body that something is wrong, pay close attention to your child's other symptoms. If he has a runny nose and a low-grade fever (under 101F), it usually means he's got a common cold, while vomiting and diarrhea probably point to a stomach virus. In both cases, the fever tends to come on gradually and to disappear within a few days. But flu symptoms often strike very suddenly. "Flu hits your child like a ton of bricks," says Jason Homme, M.D., assistant professor of pediatrics at the Mayo Clinic in Rochester, Minnesota. "One day he's fine, and then boom, the next he can't get out of bed."

For kids considered to be at higher risk (those under age 5 or with certain chronic medical conditions, such as asthma or diabetes), treatment may be needed, so your doctor might have you in for a flu test. If your child is otherwise healthy the physician may simply assume (based on your description) that he has the flu, in which case he'll need to stay home until he's fever-free for 24 hours without using a fever reducer.

· RELATED: The Dos and Don'ts of Fighting a Fever

Red Flags for Fevers

Let your doctor know right away if your child complains of a sore throat, an earache, or pain while peeing, since these ailments could signal strep throat, an ear infection, or a urinary tract infection, all of which may need to be treated with antibiotics. You should also check in with the office if your child shows symptoms of dehydration, such as if she urinates less than usual, doesn't produce any tears when she cries, or seems less alert than usual.

Although rare, certain symptoms (which are often accompanied by fever) require immediate medical attention. Head straight for the E.R. if your child is extremely short of breath, cries inconsolably, has difficulty waking, or develops a rash that doesn’t blanch when you touch it or has bruisy-looking purple spots (both could indicate meningococcemia, a potentially fatal infection of the bloodstream). 

Call 911 if her tongue, lips, or nails are blue (a sign that she may not be getting enough oxygen) or she has a stiff neck (a possible indicator of meningitis) or severe abdominal pain (which could mean appendicitis). Also call your pediatrician if your child is under 2 and her fever lasts more than 24 hours. 

For older kids, you can wait three days before calling unless she has symptoms suggestive of seasonal flu or H1N1. Ask for an appointment if your child's fever disappears and then returns a few days later, since she may have developed a secondary infection.

· RELATED: What to Do When Your Baby Has a Fever

When to Treat a Fever in Toddlers and Kids

While it's a natural instinct to treat your child's fever so he feels better, keep in mind that medication will merely mask it, not cure it. "Once a fever reducer wears off, your child's temperature may soar back up because the underlying cause is still there," says Laura Jana, M.D., a pediatrician and coauthor of American Academy of Pediatrics' Heading Home With Your Newborn.

As a general rule, you should focus on the way your child looks, feels, and acts rather than on what the thermometer says. "If you have to chase him around to give him medicine, he probably doesn't need it," says Dr. Jana. "Letting your child's fever run its course may actually help his body fight the underlying infection."

But if bringing down your little one's temperature makes him feel less crabby, it's fine to do so. For kids under 6 months, infant acetaminophen (such as Tylenol) is the only recommended fever reducer. Toddlers and kids can also take children's ibuprofen (such as Motrin or Advil), which is more effective at fighting fever but also somewhat more likely to cause stomach irritation. Never give aspirin to a child under 16—it can cause Reye's syndrome, a potentially fatal liver condition.

If your child's fever is persistent, see if your doctor recommends treating him with alternating doses of acetaminophen and ibuprofen (spacing the two meds by at least two hours). But if you go that route, be sure to record the precise doses and times to prevent the risk of an overdose.

· RELATED: What Not to Do If Your Child Is Sick

However, medication isn't the only Rx for a fever. A lukewarm bath or washcloth may temporarily cool your child off. Stay away from cold water and ice baths, though. "They'll make your child shiver, which can raise his temperature even higher afterward," Dr. Steele says. Also avoid alcohol rubs, a dangerous old-school remedy that can cause intoxication, seizures, or even coma. 

Giving your child lots of fluids—including ice pops or Jell-O—will help his body battle the illness and keep him hydrated. If he's vomiting or has diarrhea, give him an oral-rehydration-therapy drink to help replace electrolytes and fluids. Keep your child in lightweight, breathable clothing; dressing him in layers is best because he may be sweaty one minute and shivering the next. And don't forget the most helpful home remedy of all: lots of TLC.

FAQS for Child and Toddler Fevers

What type of thermometer should I use?

If your child is younger than three years old, a rectal thermometer gives the most accurate reading. You can use an oral thermometer for older children.

Can a high fever cause my child to have hallucinations?

Though adults are more likely to hallucinate from an elevated body temperature than kids are, it's possible your feverish child could start seeing things that aren't really there (such as a doll floating across her room or bugs crawling on her). High fevers—102F or above—are more likely to cause hallucinations. While they may be frightening for your child, they're harmless.

Will my child have a febrile seizure?

He could. A febrile seizure is caused by a quick spike in temperature that disrupts the brain's normal electrical activity. Your child is prone if febrile seizures run in your family or if he's had one within the past year. Though the typical symptoms—rolling of the eyes, twitching, and even vomiting—are disturbing to watch, febrile seizures rarely harm a child and don't predispose him to epilepsy. If he has one, keep him on the floor and away from sharp objects, and turn his head sideways so that his tongue doesn't obstruct his breathing. Call 911 if it lasts longer than five minutes.

If my child's fever rises above 106F, can it cause brain damage?

Yes, a fever that high can cause permanent injury, but it's almost never the result of illness alone. It's most likely to occur if your child has heatstroke (such as from being left in a hot car during the summer).

· By Leslie Gross Klaff and Nicole Harris