“How long should a fever last in a child?”

"Fever" is defined as a temperature above 100.4 measured orally, rectally, or under the arm. It's typical for temperatures to cycle throughout the day, usually getting higher in the afternoons and being the lowest upon awakening in the mornings. Fever is the body's natural response to some sort of a stressor -- usually an infection of some sort -- and the fever may be the ONLY sign of the infection. Fever is not dangerous, and there is no "number" that is potentially harmful -- the *reason* for the fever is the concern. Healthy children will typically have fevers for 3-4 days, with the pattern starting w/an elevated temp in the evenings, then all day long, then normalizing in the mornings, but "coming back" in the evenings. Documented temperatures > 101 for > 5 days is abnormal and should be evaluated by your pediatrician. Because fever is a part of the body's healthy immune response, avoid medicating with acetaminophen or ibuprofen for "numbers" on the thermometer. Use those medications to treat your child's discomfort regardless of temperature. Speak to your pediatrician to learn the proper dose for your child's weight.

Shelley C. Springer, MD, MBA, MSc, JD, FAAP

This answer is not simple. Fever is a symptom of an underlying disease, and in almost all cases the disease is an infection. For some infections, the fever will last for a day. In others, up to 7-10 days. So, it really depends on the type of infection and whether or not it is an infection that is treatable with anti infective medication. The real question is, “Why does my 5-year-old have fever?” Once that is determined, then therapy, if needed, is prescribed and the duration of fever can be predicted. Please consult your physician and ask, “What is causing the fever?”

Dr. K