Demystifying Fever

I get a lot of calls about fever typically followed by: How high is too high? When do I need to go to the ER? Do I need an antibiotic? What do I do next?

Fever is one of the first signs that the body’s immune system has been activated. There is not a magic number where treatment is required and the height of the fever does not correlate with the severity of the illness. If your fever is 101 degrees or 105 degrees, we treat it the same way. A fever by itself will never be high enough to cause brain injury. Our bodies have a limit of what they can produce without an external source (i.e. hot car, AZ in the summer). The highest temperature of a patient I treated was 107.1 degrees in a three month old with the flu. Not going to lie, I asked that family to bring her in. But my exam only confirmed a viral infection and supportive care measures were recommended. She was better in four days. Now she is 17 and getting ready to graduate with a 3.9 GPA. While impressive, the fever number did not affect final outcome.

What we are most concerned about are the symptoms associated with the fever. If you go to the emergency room with only a fever and no other symptoms, they will give you some Tylenol to lower your temperature then likely send you home. The only exception to this is the people who have compromised immune systems (you know who you are).

Symptoms that would prompt an emergency room visit are shortness of breath, unrelenting severe pain at any location that is not improved with acetaminophen or ibuprofen, signs of dehydration (see later blog), confusion, or weakness where cannot safely care for self.

The most common reason for a fever is infection, although there is a wide range of other possible causes. Viral infections are the most common of these infections. The blessing of viral infections is that they typically resolve in 5-7 days. The bane of viral infections is that there is very little that we can do to help that process. Most viruses start with fever with the rapid development of sore throat, congestion, and cough for upper respiratory infections or nausea, vomiting and diarrhea for GI bugs. They can also cause mouth ulcers and body rashes. With rest, time, adequate hydration and the variable relief from over-the-counter meds, the body’s immune system will overcome the inflammation from the virus.

Symptoms that would prompt a more rapid evaluation in a medical setting are sore throat without congestion/cough (strep), pain with urination (UTI), painful red rash (cellulitis), and bloody diarrhea stools (bacterial colitis). These are bacterial infections where antibiotics may be indicated.

If the fever lasts longer than five days or symptoms change or worsen before that, this may prompt a doctor’s visit. Secondary bacterial infections can follow primary viral infections. Some examples of this are the pediatric patient with cold symptoms for four to five days who develop new or persistent fever and ear pain or the adult patient with congestion for over 10 days with localized face pressure or brown/bloody secretions. For my patients who have fever for longer than five days, I often ask them to come in for a full examination looking for those other causes of fever besides viruses.

Tip for parents of sick kids: For pediatric patients, do not wait to medicate your child if they have a fever. They are miserable and there is no reason for you to prove your child is sick in the office. Any good provider will take your word for it that a fever is present. However, we do like it when you have a number to report. A temperature of 99-100 may not be considered a fever, but all information is helpful to us when treating patients.

Tip for all patients and parents: Trust your instincts. If what we say makes sense, you are right. If what we say does not make sense, then ask more questions. We know a lot about medicine, but we don’t know everything about you. Bring up your concerns so everyone can walk away comfortable with the treatment plan.

In summary, fever can be frightening, but it is only one part of the assessment. When my three year old had a temperature to 105 with rigors (shakes) and mottling (lots of visible veins on pale skin), I paused too. Even with all the training, when it’s your kid, fever is still tough to watch. But after a dose of ibuprofen and a little time, he perked right up. Before rushing to an urgent care, try a dose of tylenol to get the number down then reassess how things stand. Treating the whole patient should always be our goal with medicine so don’t let the number be your only decision point.

Tylenol dosing:

Adults: 500-1000 mg every six hours (max of 4000 mg/day). Pediatrics: 15 mg/kg every six hours (to calculate, weight in pounds divided by 2.2 then multiplied by 15.) An alternative is 10 mg/kg every four hours. I prefer the higher dose so a more effective dose can be given less frequently.

Ibuprofen dosing:

Adults > 132 lb, 600 mg every six hours; Adult > 176 lb, 800 mg every six hours Pediatrics > 6 months of age: 10 mg/kg every six hours (to calculate, weight in pounds divided by 2.2 then multiple by 10)

Alternating Tylenol and Ibuprofen:

Recommend discussing with health professional first. While this can be used safely for some patients, the risk of side effects increases substantially and should only be used in a well hydrated person on a short term basis like 1-2 days. Talking it over with your provider is preferred to avoid toxicities.