When health care providers cannot diagnose the cause of a patient's
temperature that reaches 101 degrees Fahrenheit on and off for at least three
weeks, they call it a fever of unknown origin (FUO). If the fever persists, your
health care provider will continue to carry out tests to narrow down the causes.
But in 5 to 15 percent of cases, they fail to find the reason for the fever.
Your health care provider may prefer not to give you medication for your
fever while it remains undiagnosed. Research suggests that fever helps fight off
infections, so treating the fever without knowing the cause might reduce the
body's ability to deal with the possible infection. However, providers will
prescribe drugs to reduce fever in children who suffer seizures induced by
fever. Because a higher temperature increases a person's need for oxygen, your
provider may prescribe fever-reducing drugs if you have heart or lung
Signs and Symptoms
Fever of more than 101°F (38.3°C), either continuous or intermittent,
for at least two weeks
Fever above 101°F whose cause remains unknown even after extensive
What Causes It?
By carrying out a series of tests, health care providers try to narrow down
the list of possible reasons for a high temperature.
What to Expect at Your Provider's Office
A provider trying to diagnose the cause of a fever of unknown origin must
seek out every possible clue. He or she may ask you questions
Your work, because some workplaces contain organisms that can cause
Places you have visited recently. Locations overseas, and even areas
in the United States, can harbor diseases that can cause
Your health care provider will also examine you closely, paying particular
attention to your skin, eyes, nails, lymph nodes, heart, and abdomen. He or she
will also take blood and urine samples. You may have an ultrasound examination,
as well as computed tomography (CT scan) and magnetic resonance imaging (MRI).
If the cause of the fever still can't be found, your provider may want to inject
you with "labeled white blood cells." These are white blood cells that contain a
harmless radioactive compound. Once injected, the white blood cells travel to
infected parts of your body. The radioactivity allows your provider to see on an
X ray just where they have moved and thus locate the infection responsible for
your fever. If that fails, your provider may want to perform minor surgery to
take biopsy samples of, for example, your liver or bone
Your health care provider will advise you to rest and drink plenty of fluids,
and may even take you off medications for other ailments, because those
medications may be causing your fever. If you have a heart or lung condition, or
if your child has seizures as a result of the fever, your provider will probably
prescribe over-the-counter remedies to bring down the temperature. The most
popular are acetaminophen and aspirin.
Aspirin and other nonsteroidal anti-inflammatory drugs. Avoid aspirin
for children and teenagers, as it increases the risk of Reye's
In cases of infection, your doctor may also prescribe an antibiotic,
antifungal, or antiviral drug, depending on the cause of the
Complementary and Alternative Therapies
General immune support with nutrition and herbs may alleviate
Eliminate alcohol, caffeine, refined foods, and sugar.
Drink water or electrolyte replacement (sports) drinks.
Vitamin C (250 to 500 mg two times per day), beta-carotene (15,000 to
50,000 IU per day), and zinc (10 to 30 mg per day) help your immune system work
better and reduce inflammation.
Herbs may be used as dried extracts (capsules, powders, teas), glycerites
(glycerine extracts), or tinctures (alcohol extracts). Unless otherwise
indicated, teas should be made with 1 tsp. herb per cup of hot water. Steep
covered 5 to 10 minutes for leaf or flowers, and 10 to 20 minutes for roots.
Drink 2 to 4 cups per day.
The following herbs may be helpful in reducing fever and improving immune
response: coneflower (Echinacea purpurea), yarrow (Achillea
millefolium), white willow bark (Salix alba), lemon balm (Melissa
officinalis), spearmint (Mentha spicata), catnip (Nepeta cateria),
and elder (Sambucus nigra). Combine 1 part coneflower and 1 part
white willow bark with equal parts of two or more herbs. Drink 3 to 4 cups per
day, 2 to 4 oz. three to four times per day for children.
Although very few studies have examined the effectiveness of specific
homeopathic therapies, professional homeopaths may consider the following
remedies for the treatment of fevers based on their knowledge and experience.
Before prescribing a remedy, homeopaths take into account a person's
constitutional type. A constitutional type is defined as a person's physical,
emotional, and psychological makeup. An experienced homeopath assesses all of
these factors when determining the most appropriate treatment for each
Aconitum -- for fever that comes on suddenly and alternates
with chills, heat, and flushing of the face; the individual may be anxious and
crave cold drinks
Apis mellifica -- for fever associated with alternating bouts
of wet (sweating) and dry body heat
Belladonna -- for sudden onset of high fever with hot, red
face, glassy eyes, lack of thirst, and hot body with cold hands
Bryonia -- for fever with symptoms that are aggravated by the
Ferrum phosphoricum -- for the first stages of a fever with a
slow onset; this remedy is generally used if Belladonna is
Acupuncture may be helpful in supporting immune
Fever can be dangerous if you are pregnant. Nutritional, herbal, and
homeopathic treatments for fevers are generally safe in pregnancy, yet use with
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Review Date: August 1999
Reviewed By: Participants in the review process include: Gary Guebert, DC, DACBR,
(Chiropractic section October 2001) Login Chiropractic College, Maryland
Heights, MO; Lonnie Lee, MD, Internal Medicine, Silver Springs, MD; Leonard
Wisneski, MD, FACP, George Washington University, Rockville, MD; Elizabeth
Wotton, ND, private practice, Sausalito, CA; Terry Yochum, DC, Rocky Mountain
Chiropractic Center, Arvada, CO.
The publisher does not accept any responsibility for the accuracy of
the information or the consequences arising from the application, use, or misuse
of any of the information contained herein, including any injury and/or damage
to any person or property as a matter of product liability, negligence, or
otherwise. No warranty, expressed or implied, is made in regard to the contents
of this material. No claims or endorsements are made for any drugs or compounds
currently marketed or in investigative use. This material is not intended as a
guide to self-medication. The reader is advised to discuss the information
provided here with a doctor, pharmacist, nurse, or other authorized healthcare
practitioner and to check product information (including package inserts)
regarding dosage, precautions, warnings, interactions, and contraindications
before administering any drug, herb, or supplement discussed