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Fever of unknown origin

• Signs and Symptoms
• What Causes It?
• What to Expect at Your Provider's Office
• Treatment Options
• Special Considerations
• Supporting Research

A fever of unknown origin (FUO) is a temperature that reaches 101°F on and off for at least 3 weeks with no known cause. Fever is a symptom of another condition, so your health care provider will continue to carry out tests for a fever that persists, to narrow down the causes and determine how to treat the underlying illness. In 5 - 15 percent of cases, however, no cause is found.

Your health care provider may prefer not to give you medication while your fever remains undiagnosed. Research suggests that fever helps fight off infections. Treating the fever without knowing the cause might reduce your body's ability to deal with the possible infection. However, health care providers will prescribe drugs to reduce fever in children who suffer seizures caused by fever (febrile seizures). Because a higher temperature increases your need for oxygen, your health care provider may prescribe fever-reducing medicines if you have heart or lung problems.

Signs and Symptoms

• Fever of more than 101°F (38.3°C), either continuous or intermittent, for at least 2 weeks
• Fever above 101°F with no known cause even after extensive diagnostic testing

What Causes It?

Fever is a symptom of several conditions. Health care providers can use a series of tests to try to narrow down the list of possible reasons for a high temperature.

What to Expect at Your Provider's Office

A health care provider trying to diagnose the cause of a fever of unknown origin must look for every possible clue. The provider may ask you questions about:

• Your work, because some workplaces contain organisms that can cause fever.
• Places you have visited recently. Locations overseas, and even areas in the United States, can harbor diseases that can cause fever.

Your health care provider will also examine you closely, paying particular attention to your skin, eyes, nails, lymph nodes, heart, and abdomen. The health care provider will also take blood and urine samples. You may have an ultrasound, computed tomography (CT scan), and magnetic resonance imaging (MRI). If the cause of the fever is still unknown, your health 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 where the cells have moved. This may show location of the infection responsible for your fever. If that test shows no results, your health provider may want to perform minor surgery to take biopsy samples of, for example, your liver or bone marrow.

Treatment Options

Your health care provider will advise you to rest and drink plenty of fluids. You may be asked to stop taking medications for other ailments, because those medications may be causing your fever. If you have a heart or lung problem, or in the case of a child who has seizures as a result of fever, your health provider will probably prescribe over-the-counter remedies to bring the temperature down.

Drug Therapies

• Acetaminophen
• Aspirin and other nonsteroidal anti-inflammatory drugs. Avoid aspirin in children and teenagers.

In cases of infection, your doctor may also prescribe an antibiotic, antifungal, or antiviral drug, depending on the cause of the infection.

Complementary and Alternative Therapies

General immune support with nutrition and herbs may alleviate fevers. Most natural medicine practitioners will treat fever as a sign that the body is trying to heal itself, rather than as an illness. In addition, most natural therapies attempt to support the body’s own healing processes rather than suppress the fever. It is important to speak to your medical doctor about any natural therapies you may be considering. Prolonged fever can be dangerous, and some natural therapies and conventional medications can have dangerous interactions.

Nutrition and Supplements

• Eliminate alcohol, caffeine, refined foods, and sugar.
• Drink water or electrolyte replacement (sports) drinks.
• Vitamin C (1,000 mg four times per day), beta-carotene (15,000 - 50,000 IU per day), and zinc (10 - 30 mg per day) help your immune system work better and reduce inflammation.

Herbs

Herbs are generally a safe way to strengthen and tone the body's systems. As with any therapy, you should work with your provider to get your problem diagnosed before starting any treatment. You may use herbs as dried extracts (capsules, powders, teas), glycerites (glycerine extracts), or tinctures (alcohol extracts). Unless otherwise indicated, you should make teas with 1 tsp. herb per cup of hot water. Steep covered 5 - 10 minutes for leaf or flowers, and 10 - 20 minutes for roots. Drink 2 - 4 cups per day. You may use tinctures alone or in combination as noted.

The following herbs may help reduce fever and improve immune response:

• Coneflower (Echinacea purpurea)
• Yarrow (Achillea millefolium)
• White willow bark (Salix alba)
• Lemon balm (Melissa officinalis)
• Spearmint (Mentha spicata)
• Catnip (Nepeta cateria)
• Elder (Sambucus nigra)

Combine 1 part coneflower and 1 part white willow bark with equal parts of two or more herbs. Drink 3 - 4 cups per day. Although white willow bark has not been linked to Reye's syndrome, it is similar enough to aspirin to cause concern in children under 16. Consult your doctor before giving white willow bark to a child. Also avoid white willow bark if you are allergic to aspirin or if you take blood-thinning medication.

Andrographis is often used to treat colds and sore throats and may also help reduce a fever. One study suggested 6 g per day for 7 days was effective with no side effects. Do not use andrographis if you have gallbladder disease, an autoimmune disease, or if you are pregnant or trying to become pregnant.

Homeopathy

Although 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 -- your physical, emotional, and psychological makeup. An experienced homeopath assesses all of these factors when determining the most appropriate treatment for each individual.

• Aconitum -- for fever that comes on suddenly and alternates with chills, heat, and flushing of the face. You 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 slightest movement.
• Ferrum phosphoricum -- for the first stages of a fever with a slow onset. This remedy is generally used if Belladonna is ineffective.
• Gelsemium -- for fever accompanied by drowsiness and lack of thirst.

Physical Medicine

• Constitutional hydrotherapy -- Involves the application of hot and cold packs to the body by a trained professional in order to evoke a general healing response by the body. With any hydrotherapy technique, it is crucial to avoid becoming chilled. All treatments should end with a vigorous rubdown.
• Wet socks treatment -- This hydrotherapy technique can be done at home. Before going to bed, soak a pair of thin cotton socks with water and then wring them out so they are damp but not dripping wet. Put them on your feet, and then put on a pair of dry thick socks (preferably wool) over them. Wear these to bed. As you sleep, your body will send blood and lymphatic fluid circulating in order to fight off the wet feeling on your feet. This stimulates the immune system and puts the body in a parasympathetic state that supports healing and restful sleep. By morning the socks should be completely dry. This technique can be done for 5 - 6 nights in a row. Then take 2 nights off and continue.

Acupuncture

Acupuncture may be helpful in supporting immune function.

Special Considerations

Fever can be dangerous if you are pregnant. Nutritional, herbal, and homeopathic treatments for fevers are generally safe in pregnancy, yet you should use them with caution.

Supporting Research

Bartram T. Encyclopedia of Herbal Medicine. Dorset, England: Grace Publishers; 1995:182.

Berkow R. Merck Manual, Home Edition. Rahway, NJ: The Merck Publishing Group; 1997.

Berkow R, Beers MH. The Merck Manual of Diagnosis and Therapy. Rahway, NJ: The Merck Publishing Group; 1992.

Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicine. Boston, Mass: Integrative Medicine Communications; 1998:427.

Carr AC, Frei B. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr. 1999;69(6):1086-1107.

Cummings S, Ullman D. Everybody's Guide to Homeopathic Medicines. 3 ^rd ed. New York, NY: Penguin Putnam; 1997: 53.

Duke JA. The Green Pharmacy. E mmaus, Pa: Rodale Press, 1997.

Fiebich BL, Appel K. Anti-inflammatory effects of willow bark extract. Clin Pharmacol Ther. 2003;74:96.

Johnston CS. Recommendations for vitamin C intake. JAMA. 1999;282(22):2118-2119.

Jonas WB, Jacobs J. Healing with Homeopathy: The Doctors' Guide. New York, NY: Warner Books; 1996: 169.

Levine M, Rumsey SC, Daruwala R, Park JB, Wang Y. Criteria and recommendations for vitamin C intake. JAMA. 1999;281(15):1415-1453.

Morrison R. Desktop Guide to Keynotes and Confirmatory Symptoms. Albany, Calif: Hahnemann Clinic Publishing; 1993:6, 58, 62.

Thamlikitkul V, Dechatiwongse T, Theerapong S, et al. Efficacy of Andrographis paniculata, Nees for pharyngotonsillitis in adults. J Med Assoc Thai . 1991;74:437–442

Ullman D. Homeopathic Medicine for Children and Infants. New York, NY: Penguin Putnam; 1992: 84.

Walker LP, Hodgson E. The Alternative Pharmacy. Paramus, NJ: Prentice Hall Press; 1996.

• Review Date: 6/30/2006
• Reviewed By: Steven D. Ehrlich, N.M.D., private practice specializing in complementary and alternative medicine, Phoenix, AZ. Review provided by VeriMed Healthcare Network.

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