"Fever," regardless of its context, is a word that arouses passion. This is certainly true in the emergency department, where it is an important but often misunderstood symptom.
Since early history, fever has been recognized as a sign of disease and so it has been feared. The ancient Greeks knew that willow bark could be used to lower a person's temperature. In the late 1800s, a Swiss chemist used a chemical found in the willow to formulate aspirin. Thus began the modern idea (and industry) of fever treatment. In spite of all our medical knowledge, many people still are afraid of an elevated body temperature, and they use the modern day equivalents of willow bark to "break the fever."
Fever is a body temperature above 100.4 degrees F. It is the result of complex interactions among foreign proteins, our body's immune system, and our body's thermostat--a part of the brain called the hypothalamus. Among its many functions, the hypothalamus controls the body's ability to raise or lower its temperature. The most frequent cause of fever is what is commonly called an infection--bacteria, viruses, or parasites are attacking the body.
Why do doctors and nurses always ask about your temperature? A fever is a clue that your immune system is busy. We have learned that when a fever is above 104 degrees or it lasts for more than 3 to 4 days, the chance of having a serious illness is increased. Some of these illnesses require treatment with antibiotic medications; some do not. (Note: All infants younger than 3 months with any fever should be seen by a doctor.)
Is fever by itself dangerous? Rarely. The body's temperature almost never rises above 106 degrees unless there is a brain injury, a toxic drug reaction, or the environment is extremely hot. It would be very unusual for an infection to cause a fever higher than 106. Below this temperature, there is no risk of any damage from the fever itself.
Why do we treat fever? Every shift I work I can count on hearing some variation of, "I tried everything but I can't get the fever down!" Many people still have the mistaken belief that fever is dangerous and needs to be lowered. As physicians, we must accept some of the blame for propagating this belief. In our desire to help patients feel better, we often prescribe fever-lowering drugs for the comfort they may offer. It is easy to understand why people have the idea that doctors think these drugs are necessary. In fact, there are few medical reasons to lower a person's fever.
How do these drugs work? Aspirin and its modern day relatives--acetaminophen and ibuprofen--are often effective in lowering a fever because they interfere with the chemical signals that increase the body's temperature.
Is it harmful to treat a fever? We don't really know. It took doctors 100 years to learn that aspirin, our modern day willow bark, should not be used in children because it can cause a fatal disease called Reyes syndrome. The drugs currently used for both children and adults, acetaminophen and ibuprofen, appear to be safe. However, prudence might support a more cautious approach to the chemicals we put in our body.
Might fever be beneficial? Healers through the ages have certainly explored this idea. Although modern research suggests that fever is a useful part of our immune system, this is actually a very difficult question to answer. Unfortunately, there is little commercial incentive to find out. The next century should prove interesting as we try to unlock this puzzle.
In the mean time, try not to worry so much about fever. The other symptoms that accompany the fever are far more important than that number on the thermometer.
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