How Do I Determine If a Fever Is Serious?

Fevers, whether they accompany other symptoms of illness or occur on their own, can be uncomfortable and scary, especially a high fever or one that occurs in an infant. Most fevers aren't serious and will go away on their own or as the illness they accompany resolves. The seriousness of a fever depends upon the age of the person who gets one, her temperature, the duration of the fever and the accompanying symptoms.

Fever

There are a few events that result in development of a fever. If you get overheated -- you're in the sun all day and get dehydrated, for instance -- your body can lose its ability to cool itself, and your temperature will go up. Fevers can be the result of your body purposely raising its temperature in response to a viral or bacterial infection. While your brain normally works to maintain your temperature at around 98.6 degrees Fahrenheit, if you're ill, your temperature "set point" will go up, and your brain will purposely allow you to get hotter. This helps your immune system get rid of the infection.

Age and Temperature

Fevers in adults aren't generally serious unless they're higher than 103 degrees Fahrenheit, explains MayoClinic.com. In fact, fevers under 102 F. in adults are best left untreated unless your doctor advises otherwise, because treating a fever decreases your immune system's ability to fight infection. If you have a fever above 103 degrees, contact your doctor. For infants younger than 6 months, fevers of 101 degrees or more are a medical emergency, says pediatrician Dr. William Sears, while babies up to three months should see a doctor right away for a fever of 101 or more. In older infants and children, you may wish to call your child's doctor in the morning for a fever between 101 and 103 degrees, but it's probably not worth a nighttime call. Fevers of more than 104 degrees warrant an immediate doctor visit.

Duration of Fever

Even a low-grade fever can indicate a serious problem if it goes on for a long time. The American Academy of Family Physicians notes that a low-grade fever that lasts for weeks and is accompanied by fatigue and a sore throat could be mononucleosis, an infection that warrants a visit to the doctor. Similarly, a fever that comes and goes for weeks and is accompanied by weight loss and swollen lymph nodes could be a serious infection such as tuberculosis, and you should see your doctor for testing. Generally speaking, if a fever lasts more than three days, you should probably talk to your doctor, explains MayoClinic.com When you get a fever is also important; if you get a fever suddenly after taking a new medication, the fever could be a reaction to the drug, and you should call or see your doctor right away.

Accompanying Symptoms

Even a low-grade fever can indicate a serious problem if it goes on for a long time. The American Academy of Family Physicians notes that a low-grade fever that lasts for weeks and is accompanied by fatigue and a sore throat could be mononucleosis, an infection that warrants a visit to the doctor. Similarly, a fever that comes and goes for weeks and is accompanied by weight loss and swollen lymph nodes could be a serious infection such as tuberculosis, and you should see your doctor for testing. Generally speaking, if a fever lasts more than three days, you should probably talk to your doctor, explains MayoClinic.com When you get a fever is also important; if you get a fever suddenly after taking a new medication, the fever could be a reaction to the drug, and you should call or see your doctor right away.