When Is a Fever Really a Fever? And When Should You Treat It?
- Victoria Wermers, RN,MSN,FNP, PMHNP
- Oct 1, 2024
- 7 min read
Updated: Jul 1
What Exactly is Considered a Fever?
For years, I have listened to patients tell me: "I never run a fever," and "My temperature is always low."
Then, one day, a patient came along, and we discussed this. He told me that 98.6 is not a valid norm and recommended I Google some reputable sources. So, I followed his lead and learned that the average oral temperature is actually lower than 98.6°F!
According to an article by the National Institute of Health (NIH), "the average temperature is actually closer to 98.2°F. The norm of "98.6F...should be abandoned." (Another study even suggests that the norm is 97.9°F!).
Scientists arrived at the "normal" human temperature of 98.6°F in the 1800s when equipment was not very accurate. Some suggest that the human body is getting cooler over time.
So, why do they continue to teach healthcare providers that 98.6 F is an average human oral temperature? Perhaps too many things we base on the norm of 98.6 would have to change if the old norm is officially changed—i.e., equipment, paperwork, and medical protocols. It's not clear why this has not been changed.
What is A Normal Temperature?
The following are discussions based on oral temperature.
Everyone has their own body temperature. Under normal circumstances, a person's body temperature can range from 97°F to 99°F and can vary by as much as 1.3 degrees in one day! Typically, it is lower in the morning and higher in the evening. Many factors can affect a person's normal temperature. A person's health, sex, emotions, height, weight, exertion, and hormones—including thyroid hormones—affect temperature. Older people generally tend to have an average lower temperature, which can put them at risk (i.e., if they typically run 95°F, they will have a fever when their temperature rises 2.4°F higher at 97.5°F! That fever can go unrecognized!)
How to Determine Your Normal Temperature
Here is a way to determine your average temperature if you want to be attuned to your body. When you are well, you can find your baseline by checking your temperature daily for about two weeks. Check in the morning and, again, late in the afternoon or early evening. Write each down, keeping an "am" column and a "pm" column. At the end of two weeks or so, average them out or see what your range tends to be in the morning and the evening. That should give you an idea of your average temperature at different times of day.
So, What Temperature Really Means I Have a Fever?
An increase of about 2 degrees F (2°F) is generally considered a fever. So, if you usually run 97.6°F, adding 2°F would tell you that that is your fever point (99.6°F). If you typically run 98.3°F, then 100.3°F would be the point at which you have a fever, and so on. Based on the current "norm" of 98.6°F, most medical professionals consider 100–100.4°F (38°C) a fever. 99.1–100.4°F is considered a "low-grade fever." If I see a patient who is feeling ill and has not taken a fever-reducing agent with a temperature of 99°F or higher, it is possible that the patient may be starting to fight off an illness.
When Should I Treat a Fever?
A fever has a vital function. An increase in body temperature helps the body fight off viruses and bacteria. When you lower your fever with medicine, you may be lowering your immune response.
You can treat your fever whenever you feel it is necessary, especially when it is accompanied by discomfort like body aches and chills. Most practitioners recommend that you try to treat with fever-reducing agents when it reaches 102F (or higher).
Remember, the body is a smart, incredible machine designed to protect you. You get a fever because your body has a purpose: To fight off illness.
It is very important to be cautious with fever in those with underlying medical conditions, older adults, and infants. You often want to treat these people earlier and/or consult a healthcare provider.
What Are the Best Ways to Treat a Fever?
Over-the-Counter (OTC) Medications for Fever Reduction
As with most pills, it usually takes between 30 minutes to one hour for most of these to start working.
Adolescents and Adults:
Ibuprofen (Advil, Motrin), NSAID (Non-steroidal anti-inflammatory) - A dose of 200-400 mg every 4 - 6 hours should be adequate to bring down a fever in an average person (over 12 years of age). An adult can take 600 mg every 6 hours as needed (over 15 years of age). It is a good medicine if you have a fever with body aches or inflammation because of its anti-inflammatory properties.
Read Instructions, Warnings, and Side Effects - Gastrointestinal, blood pressure, and kidneys.
Acetaminophen (Tylenol) - Regular strength - 325 mg - Take 1-2 every 4-6 hours as needed. There is also a Tylenol Extra Strength - 500 mg - Take 2 every 6 hours. It's not good for those with liver problems.
Naproxen (Aleve)-220 mg- NSAID- Take one every 12 hours as needed for a fever. The benefit of this medicine is that you take it less frequently than acetaminophen or ibuprofen.
It will help with both a fever, inflammation, and body aches. READ THE LABEL (side effects and contraindications).
Acetylsalicylic acid—Aspirin (Bayer, Excedrin, Bufferin, St Joseph)-NSAID—325 mg and 500 mg—Take one or two every six hours as needed for fever or pain.
Read the label—These thin blood, so avoid them if you are on blood thinners or have bleeding problems. They may also have gastrointestinal effects and may cause problems with asthma. While this is not a site for kids, this is a reminder to AVOID with young children.
Note: There are many generics listed under the names for acetaminophen, ibuprofen, aspirin (acetylsalicylic acid), and naproxen. They typically work as well as the brand-name medications and are quite a bit cheaper.
Other Approaches to Reduce a Fever
Lukewarm (not cold baths) - for high fever only
Dress in lighter clothing (thick clothing may make your fever go up)
Considered Alternative Remedies for Fever
Feverfew (herbal)
Willow Bark (Aspirin originated from this in 1900s)
Prescriptive Treatment for a Fever
Most healthcare providers will recommend over-the-counter medications for a fever.
See a healthcare provider if you have a lingering fever (days to weeks) and ongoing symptoms. Sometimes, it indicates a long-term illness or immune problems. In most cases, the provider can test for and treat the underlying illness with prescriptions, which may help reduce the fever.
Consider going to the ER if you have -
A severe headache, neck pain, or stiff neck
Vomiting (especially if you cannot keep fluids down or it is projectile [forceful] vomiting)
Vision problems/double vision, or photophobia
Confusion
Seizures
Rash
Abdominal pain
If you cannot reduce a high fever (be sure you are taking the correct dosage of an antipyretic [anti-fever] over-the-counter medication). Sometimes, I meet patients who are barely taking enough.
You are an older person or someone with an underlying illness like diabetes, heart disease
Concurrent breathing problems
It's true that no one really wants to hang around an ER because there are other sick people there and because it takes time and money, but in the ER, they can do immediate testing and treatment that they cannot do elsewhere.
Drink plenty fluids - especially water (people easily get dehydrated when they have a fever)
Q&A
Why do people alternate Ibuprofen (Motrin, Advil) with acetaminophen (Tylenol)? And how often should I take each?
It is unnecessary to alternate unless a person has a stubborn fever or pain (especially) that is not responding very well to just one medicine.
Usually, this is done by giving acetaminophen and ibuprofen doses three hours apart, alternating the medications.
What is the best way to take a temperature?
Rectal thermometers are the most accurate (please do not use glass thermometers). Subtract a degree to get the equivalent of an oral temperature.
Oral - Very good if done correctly (under the tongue with mouth closed). Do not use a digital thermometer rectally unless indicated on the package.
Axillary - One of the least accurate methods, but better than nothing. Add a degree to equal oral.
Tympanic (ear) - Fair method, add a degree to equal oral. Sometimes, wax or canal curvature gets in the way of accuracy.
Forehead Scanner—Add 0.5 or 1 to equal oral. It is convenient and quick, but after using this method a lot during COVID, I am not crazy about this method. It seems that many things can affect the reading, like ball caps, bangs, and warm outside temperatures. It is BETTER THAN NOTHING, but if there is any question about accuracy, "You sure feel warm, but your temperature is normal." Try another method if you have one.
Paper or plastic strip (Tempa-Dot) thermometers applied to the forehead are considered reliable.
The "back of the hand" method. Lots of parents use this method "well, Johnny felt warm so I think he had a fever." What can I say??
Note: Most digital thermometers can be used to take oral, rectal, and axillary temperatures.
Do not use a mercury thermometer (mercury is toxic)
Does it make any sense to bundle up and sweat out a fever?
Because a fever helps fight off infection, it seems that making your body warm or "sweating things out" would help eliminate infection. Sometimes, it really seemed like it helped—you go to sleep, sweat it out, and wake up feeling better! (Maybe it was just a coincidence.) There is, however, no evidence of this.
"Feed a cold, starve a fever"?
In the Middle Ages, people used to say, "Feed a cold, starve a fever." This was borne of the belief that a cold without a fever was a different illness from a cold with a fever. They believed that eating would help a cold without a fever get better, and starving it would help a febrile illness get better. Eating—even a little something—would be best when you are ill. In our North American culture, most people believe you NEED nutrition and plenty of fluids to get better (forget the solid foods for a bit if someone is vomiting!)
Why do I need a prescription for 800 mg of ibuprofen tablets when I can just take 4 of the 200 mg tablets? You can do it either way, but the higher the dose, the more potential harmful side effects there are. So, the 800 mg dose is more closely monitored through prescription.
