- Spanish Health Illustrated Encyclopedia
- Complementary and Alternative Medicine
- Condition Symptom Links
- Drug Category
- Supplement Depletion Links
- Supplement Warning Links
- Herb Interaction
- Herb Side Effect Links
- Supplement Use Links
- Supplement Side Effect Links
- Herb Warning Links
- Herb Use Links
- Supplement Interaction
- Wellness Tools
- Thomson DrugNotes
- In-Depth Reports
- Pregnancy Center
- Care Guides
- Spanish Surgery and Procedures
- Health Illustrated Encyclopedia
- Thomson DrugNotes Spanish
- Spanish Pregnancy Center
- Surgery and Procedures
- Complementary and Alternative Medicine
Fever of unknown origin
A fever of unknown origin 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 up to 50% 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 3 weeks
- Fever above 101 °F with no known cause, even after extensive diagnostic testing
What Causes It?
Fever is a symptom of several conditions. In general, infection accounts for about 25% of cases of fever of unknown origin, followed by neoplasm and noninfectious inflammatory diseases. 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 exposure to pets and other animals.
- Your family history for possible hereditary causes of fever, for example, familial Mediterranean 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, magnetic resonance imaging (MRI), and Positron Emission Tomography (PET). 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 the 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.
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 care provider will probably prescribe over the counter remedies to bring the temperature down.
- Acetaminophen (Tylenol)
- Aspirin and other nonsteroidal anti-inflammatory drugs. Avoid aspirin in children and teenagers. Reye syndrome is a potentially fatal disease that causes numerous detrimental effects to many organs, especially the brain and liver. It is associated with aspirin consumption by children with viral diseases, such as chicken pox.
- 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
These nutritional tips may help improve immunity:
- Eat antioxidant foods, including fruits (such as blueberries, cherries, and tomatoes), and vegetables (such as squash and bell peppers).
- Avoid refined foods, such as white breads, pastas, and sugar.
- Eat fewer red meats and more lean meats, cold water fish, tofu (soy) or beans for protein.
- Use healthy cooking oils, such as olive oil or vegetable oil.
- Reduce or eliminate transfatty acids, found in commercially baked goods, such as cookies, crackers, cakes, French fries, onion rings, donuts, processed foods, and margarine.
- Avoid coffee and other stimulants, alcohol, and tobacco.
- Drink 6 - 8 glasses of filtered water daily.
- Exercise at least 30 minutes daily, 5 days a week, although while experiencing intermittent fevers, your health care provider may suggest mostly rest and some gentle stretching rather than your typical exercise regimen.
You may address nutritional deficiencies with the following supplements:
- A multivitamin daily, containing the antioxidant vitamins A, C, E, the B-complex vitamins, and trace minerals such as magnesium, calcium, zinc and selenium.
- Omega-3 fatty acids, such as fish oil, 1 - 2 capsules or 1 - 2 tablespoons of oil daily, to help decrease inflammation. Omega-3 fatty acids may increase the effect of blood thinning medications such as Coumadin; speak with your physician.
- Acidophilus (Lactobacillus acidophilus), 5 - 10 billion CFUs (colony forming units) a day, for maintenance of gastrointestinal and immune health. Some acidophilus products may need refrigeration -- read the label carefully.
- Vitamin C, 500 - 1,000 mg daily, as an antioxidant.
Herbs are generally a safe way to strengthen and tone the body's systems. As with any therapy, you should work with your health care provider to choose the safest and most effective herbal therapies before starting any treatment. You may use herbs as dried extracts (capsules, powders, teas), glycerites (glycerine extracts), or tinctures (alcohol extracts). Unless otherwise indicated, 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:
- Green tea (Camelia sinensis) standardized extract, 250 - 500 mg daily, for immunity. You may also prepare teas from the leaf of this herb.
- Cat's claw (Uncaria tomentosa ) standardized extract, 20 mg 3 times a day, to improve immunity.
- Reishi mushroom (Ganoderma lucidum) standardized extract, 150 - 300 mg 2 - 3 times daily, for immunity. You may also take a tincture of this mushroom extract, 30 - 60 drops 2 - 3 times a day.
- Milk thistle (Silybum marianum ) seed standardized extract, 80 - 160 mg 2 - 3 times daily, for detoxification support.
- Andrographis (Andrographis paniculata ), 6 g daily as a tea, is often used to treat colds and sore throats and may also help reduce a fever in Traditional Chinese Medicine. One clinical study suggested 6 g a 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.
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.
- Constitutional hydrotherapy involves the application of hot and cold packs to the body by a trained professional 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 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 wetness 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 may help support immune function.
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.
Bleeker-Rovers CP, van der Meer JW, Oyen WJ. Fever of unknown origin. Semin Nucl Med. 2009; 39(2):81-7
Bleeker-Rovers CP, van der Meer JW. Diagnostic approach to fever of unknown origin. Ned Tijdschr Geneeskd. 2008; 152(15):869-73
Bryan CS, Ahuja D. Fever of unknown origin: is there a role for empiric therapy? Infect Dis Clin North Am. 2007;21(4):1213-20.
Cabrera C, Artacho R, Gimenez R. Beneficial effects of green tea -- a review. J Am Coll Nutr. 2006;25(2):79-99.
Chen Y, Zheng M, Hu X, et al. Fever of unknown origin in elderly people: a retrospective study of 87 patients in China. J Am Geriatr Soc. 2008;56(1):182-4.
Cunha BA. Fever of unknown origin: clinical overview of classic and current concepts. Infect Dis Clin North Am. 2007;21(4):867-915.
Gonclaves C, Dinis T, Batista MT. Antioxidant properties of proanthocyanidins of Uncaria tomentosa bark decoction: a mechanism for anti-inflammatory activity. Phytochemistry. 2005;66(1):89-98.
Keidar Z, Gurman-Balbir A, Gaitini D, Fever of unknown origin: the role of 18F-FDG PET/CT. J Nucl Med. 2008; 49(12):1980-5
Knockaert DC. Recurrent fevers of unknown origin. Infect Dis Clin North Am. 2007;21(4):1189-211.
Mandell. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases, 7th ed. Philadelphia, PA: Churchill Livingstone, An Imprint of Elsevier; 2009
Norman DC, Wong MB, Yoshikawa TT. Fever of unknown origin in older persons. Infect Dis Clin North Am. 2007;21(4):937-45.
Tolia J, Smith LG. Fever of unknown origin: historical and physical clues to making the diagnosis. Infect Dis Clin North Am. 2007;21(4):917-36.
Yoon JH, Baek SJ. Molecular targets of dietary polyphenols with anti-inflammatory properties.Yonsei Med J. 2005;46(5):585-96.