When Is a Fever Too High?

Many people, especially parents, worry about fevers and want to know how high is too high. In general, high-grade fevers are around 103 to 104 degrees Fahrenheit, and anything over 104 F is considered dangerous. However, in practice, gauging a fever's danger is more complicated than just looking at a number—especially when it comes to children.

The good news is that medical evidence shows a fever is rarely dangerous for the majority of people. Most of the time, a fever isn't going to fry your brain. This may go against what you have been taught to fear. As well, there is often very little that will be done at the ER that can't be done at home to bring a fever down.

Fevers are actually a good thing. They are a natural way that our bodies fight off infections. A part of the brain called the hypothalamus acts as a thermostat for the body. Most of the time, it keeps our body temperatures around 98.6 F (37 C). But when we get sick, the thermostat resets and increases the temperature of the body to make it more difficult for germs to live and multiply.

If you or your child has a fever but are still fine for the most part, treatment is not necessary. If your child is playing and still has energy, there is no need to treat the fever.

However, many times an increased temperature will make us feel pretty bad. Our bodies ache, we have no appetite, and it's hard to do much of anything. If this is how you are feeling, taking a fever reducer like Tylenol (acetaminophen) or Motrin/Advil (ibuprofen) should help you feel better.

The effects of these medications are only temporary, though. They work for 4 to 8 hours and then wear off, meaning your fever may come back and you may need to take more medication. This doesn't mean something is wrong or that it didn't work.

For most adults and older children, the number on the thermometer is not important when determining if a fever is something to worry about. However, that is not the case with younger children.

If your child falls into one of these age groups, this is what you need to watch for.

If your baby is younger than 3 months old and has a fever higher than 100.4 F, contact her healthcare provider or go to the emergency room. A fever in an infant this young can indicate a potentially serious illness.

If your child is between the ages of 3 months and 3 years old and has a fever higher than 102.2 F, contact your healthcare provider—even if it's after hours. The doctor can help you determine what's causing the fever and whether your child needs to be seen.

If you are looking for an absolute cut-off number when it comes to fevers —107.6 F is it. The body temperature almost will never get this high on its own without some sort of extenuating circumstances, such as being in an extremely hot environment (which is technically hyperthermia, not fever) or an existing neurological condition that affects the function of the hypothalamus.

In most cases, what you need to watch for is behavior and other symptoms, not the number on the thermometer.

If you are caring for a child with a fever and she is playing, smiling and eating or drinking, it is unlikely that there is any cause for concern.

However, if you are caring for a child with a fever and he won't smile or play at all, even after taking fever reducers (remember: they can take an hour to work), you should contact his healthcare provider or seek medical attention.

A Word From Verywell

Adults are typically better able to determine when our symptoms are making us feel so bad that we need to seek medical treatment, but if you aren't sure, evaluate what is going on. Learn how to check your cold and flu symptoms, evaluate a fever, and know the situations when you should see a doctor for a fever.