temperature greater than 100.4°F (38.0°C)
- Oral temperature greater than 99.5 F (37.5 C)
- Ear (tympanic) temperature greater than 99.5 (37.5 C), when
in oral mode
- Forehead temperature strips are unreliable
- In most
clinical situations, fever does no major harm, and may actually benefit the
human body by helping it to fight off infection. Nevertheless, fever is an abnormal
finding. It can signal a serious illness, especially in adults who are old,
frail, or have a weakened immune system.
- Adults tend to run lower fevers than children. Fever may be
further blunted or even absent in elderly patients.
- Fever itself can cause muscle aches, nausea, lightheadedness,
weakness and headache.
Normal Body Temperature
- 98.6 F
(37 C) is the oral temperature that most physicians, nurses, laypersons, and
medical references state is "normal."
- The average temperature of healthy elderly patients is the same
as younger adults. However, there is some data to suggest that the average temperature
in chronically ill elderly patients is lower than that of other healthy adults.
Thus, interpretation of a temperature reading in a chronically ill elderly adult
must be done with caution. Because lower baseline temperatures can be expected
in this group of patients, it may be easy to miss a fever if the conventional
fever definition is used.
Normal Variations in Body Temperature
- There is
a normal daily awake-sleep cycle variation in temperature, with the low occurring
at 6 AM and the high occurring at 6 pm. The low and high temperatures vary by
0.9 F (0.6 C).
- In women, temperature increases about 0.9 F (0.6 C) at the time
- Temperature can go up in response to physical activity, particularly
during hot weather.
See More Appropriate Topic (instead of this one) If
WHEN TO CALL YOUR DOCTOR FOR FEVER
Call 911 Now (you may need an ambulance) If:
to awaken or acting confused
- Very weak (can't stand)
- Severe difficulty breathing (e.g. struggling for each breath,
unable to speak)
- Lips or face are bluish now
- Rash with purple (blood-colored) spots or dots
Call Your Doctor Now (night or day) If:
- You feel weak
or very sick
- Fever of 103 F (39.4 C) or higher
- Fever of 100.5 F (38.1 C) or higher and you
- Are over 60 years of age
- Have diabetes mellitus or a weakened immune
system (e.g. HIV positive, cancer chemotherapy, chronic steroid
- Are bedridden (e.g. nursing home patient,
stroke, chronic illness, recovering from surgery)
- Are a transplant patient (e.g. liver, heart, lung, kidney)
- Headache and stiff neck (can't touch chin to chest)
- Difficulty breathing
- Signs of dehydration (e.g. no urine in more than 12 hours, very
dry mouth, lightheaded, etc.)
- Have an intravenous catheter (e.g. central line, PICC, or peripheral
Call Your Doctor Within 24 Hours (between 9am
and 4pm) If:
- You think
you need to be seen
- Fever of 100.5 F (38.1 C) or higher and you have traveled to
a foreign country in the last month
- Fever lasts longer than 3 days (72 hours)
Call Your Doctor During Weekday Office Hours If:
- You have
other questions or concerns
Self Care at Home If:
- Fever with no signs of serious infection and you don't think you need to be seen
HOME CARE ADVICE FOR FEVER
Most fevers are good, because they help the body fight infection. The
goal of fever therapy is to bring the fever down to a comfortable level.
Use the following definitions to help put your level of fever into
- 99.5 - 101 F Oral Low-grade fevers and beneficial (37.5 - 38.3
- 101 - 103 F Oral Moderate-grade fevers
and beneficial (38.3 - 39.4 C)
- 103 - 105 F Oral High fever that causes headache and malaise,
generally harmless in healthy adults, but higher risk of bacterial infection
(39.4 - 41.7 C)
- Over 105 F Oral Very high fever (> 41.7 C)
For All Fevers:
- Give cold fluids orally to prevent dehydration. (Reason: good
hydration replaces sweat and improves heat loss via skin) Adults should drink
6-8 glasses of water daily.
- Dress in 1 layer of lightweight clothing
and sleep with 1 light blanket.
- For fevers 100-101 F (37.8-38.3 C), this is the only treatment
and fever medicine is unnecessary.
Fever Medicine: For fevers above 101 F (38.3 C) take acetaminophen
every 4-6 hours (e.g. Tylenol; adult dosage 650 mg) or ibuprofen every 6-8 hours
(e.g. Advil, Motrin; adult dosage 400 mg). The goal of fever therapy is to bring
the fever down to a comfortable level. Remember that fever medicine usually
lowers fever 2 degrees F (1 - 1 1/2 degrees C).
- Do not take ibuprofen if you have stomach problem, kidney disease,
are pregnant, or have been told by your doctor to avoid this type of anti-inflammatory
drug. Do not take ibuprofen for more than 7 days without consulting your doctor.
- Do not take acetaminophen if you have liver disease.
- Read the package instructions thoroughly on all medications
that you take.
Lukewarm Shower for Reducing Fever: Take the fever medicine first.
Take a lukewarm shower or bath for 10 minutes. Lukewarm water should be warm
enough that it does not make you shiver, but cold enough that it helps cool
you off and reduce your temperature. Do not sponge yourself with rubbing
Expected Course: Most fevers from a viral illness such as a cold fluctuate
between 99.5 and 103 F (37.5 - 39.5 C) and last for 2 or 3 days.
Contagiousness: You can return to work or school after the fever is
- Call Your Doctor If:
- Fever lasts longer than 3 days (72 hours)
- You become worse or develop any of the "Call Doctor Now"
This information is not intended be a substitute for professional medical
advice. It is provided for educational purposes only. You assume full
responsibility for how you choose to use this information.
Adult HouseCalls Online. Copyright © 2000-2004
David Thompson, M.D. FACEP
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