Fever of Unknown Origin

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 problems.

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 diagnostic testing

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 such as:

• 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. 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 marrow.

Treatment Options

Treatment Plan

Treatment will begin on any known disease or condition that is causing your fever. Your health care provider may suggest rest and drinking plenty of fluids if the cause is unknown. Anyone with a heart or lung condition and children who have seizures with fever must take fever-lowering medications. A drug you are already taking may be stopped if it is suspected of causing your fever.

Drug Therapies

Prescription

• Antibiotic antimicrobial antifungal and antiviral drugs are types of medications used to treat conditions causing your fever.

Over the Counter

• Nonsteroidal anti-inflammatory drugs—reduce fever relieve pain; do not give aspirin to children under 18 years of age as it increase the risk of getting Reye's syndrome; various side effects
• Acetaminophen (Tylenol)—reduces fever relieves pain

Complementary and Alternative Therapies

General immune support with nutrition and herbs may alleviate fevers.

Nutrition

• Eliminate alcohol caffeine refined foods and sugar.
• Drink water or electrolyte replacement (sports) drinks.
• Vitamin C (250 to 1 000 mg two to three 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

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 purpura) yarrow (Achillea millefolium) white willow bark (Salix alba) lemon balm (Melissa officinalis) spearmint (Mentha spicata) catnip (Nepeta cateria) and elder (Sambucus canadensis). 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.

Homeopathy

Some of the most common remedies used for fever of unknown origin are listed below. Usually the dose is 12X to 30C every one to four hours until your symptoms get better.

• Aconite when fever comes on suddenly and alternates with chills heat and flushing of the face. Use if you feel anxious and thirsty for cold drinks.
• Apis mellifica for fever with alternating sweats and dry heat.
• Belladonna for sudden onset of high fever with hot red face glassy eyes thirstlessness and hot body with cold hands.
• Bryonia for fever with marked aggravation from the slightest movement.

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 use 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. Boston Mass: Integrative Medicine Communications; 1998:427.

Duke JA. The Green Pharmacy. Emmaus Pa: Rodale Press 1997.

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

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

Copyright © 2000 Integrative Medicine Communications

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 herein.