Table of ContentsView AllTable of ContentsFever of Unknown OriginPossible Causes of FUOWhy Blood Cancers Cause FeversFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Fever of Unknown Origin
Possible Causes of FUO
Why Blood Cancers Cause Fevers
Frequently Asked Questions
Some cancers do cause afever, although most of the time a high temperature is due to an infection that’s easily managed and runs its course. Fatigue and other symptoms typically arise with infections, too.
Yet fever symptoms are associated with specific types of cancer,leukemiaandlymphomaamong them. What healthcare providers refer to as a “fever of unknown origin” (FUO) is just one clue toward a diagnosis and treatment.
This article defines what FUO is and some of its possible causes. It details why fever can be anearly symptomof leukemia and other cancers.
Paul Bradbury / Getty Images
“Fever of unknown origin” is the term used to describe a fever that meets all of the following criteria:
Keep in mind that an FUO has to be prolonged, so that generally rules out the flu, a routine cold, or many of the other common causes of fever that would be expected to resolve within three weeks.
FUO doesn’t automatically indicate cancer. There are more than 200 possible diagnoses associated with FUO, some of them quite rare. In up to 50% of FUO cases, the cause of fever is never found. But in 20% to 30% of all FUO cases, leukemia, lymphoma, or colorectal cancer (CRC) are the reason.
Given that there are hundreds of possible causes of FUO, the list of possible diagnoses—even for fevers lasting longer than three weeks—is quite long. Many of these causes fall into one of three categories: infection, cancer and other diseases, or medication.
Infections That Cause Fever
Many types of infections can lead to fever of unexplained origin. It’s common fornausea, fatigue, and other symptoms to arise with the fever, depending on the cause. Conditions may include:
Fever associated with an infection remains the leading cause of FUO.
Cancers That Cause Fever
Several different types of cancer may include FUO as a symptom. These cancers include:
Early Symptoms of Leukemia"Leukemia fever” may be one early sign of the disease. Other early symptoms of leukemia include fatigue, enlarged lymph nodes, frequent nosebleeds, unexplained bruising, body pains, night sweats, and weight loss.
Early Symptoms of Leukemia
“Leukemia fever” may be one early sign of the disease. Other early symptoms of leukemia include fatigue, enlarged lymph nodes, frequent nosebleeds, unexplained bruising, body pains, night sweats, and weight loss.
However, a number of other health conditions may begin with infection and/or inflammation. They also may include FUO as a symptom. Among these conditions are:
Medications That Cause Fever
Sometimes drugs may be to blame, including certain antibiotics and medications that are taken to prevent seizures. Drugs that can lead to FUO include sulfa-based products, such asstool softeners, and even pain medications like nonsteroidal anti-inflammatory drugs (NSAIDs).
These “drug fevers” are more common if you have taken a drug for years, and less so when it is a new medication. In most cases, the fever goes away within 72 hours if you stop taking the drug.
Be sure to speak to your healthcare provider about your FUO and any related symptomsbeforeyou stop taking any medication you suspect may be the cause.
What Is Chemo Fever? Definition, Treatment, Prevention
Two kinds of blood cancer, leukemia and lymphoma, are known to produce fevers as an early sign.
For example, about 25% of people with Hodgkin’s lymphoma may have what are called “B symptoms.” These include fevers, unintentional weight loss, and drenching night sweats. These symptoms suggest a more aggressive and rapidly growing cancer.
When blood cancers do cause fevers, those fevers can, in some cases, impact the stage and prognosis (or outlook) of the illness.
Why Do People Get Fevers With Cancer?The answer may depend on the type of cancer. For example, lymphoma cancer cells may cause the release of chemicals in your body that cause an intermittent high temperature in the absence of infection.The same principle is believed to be at work with leukemia fevers.
Why Do People Get Fevers With Cancer?
The answer may depend on the type of cancer. For example, lymphoma cancer cells may cause the release of chemicals in your body that cause an intermittent high temperature in the absence of infection.The same principle is believed to be at work with leukemia fevers.
Differences Between Leukemia and Lymphoma
Summary
That said, fever is a common symptom in some types of cancer, including leukemia and lymphoma. These cancers of the blood are known to cause a fever in their early stages.
If you have an unexplained fever, be sure to work closely with a healthcare provider to rule out the more obvious causes, such as an adverse drug reaction. It’s important to give a precise medical history and tell them about any other signs or symptoms that arise.
A Word From Verywell
Most FUOs will resolve on their own once the underlying cause is addressed. That said, don’t ignore an unexplained fever, especially one that recurs. It may be an important clue about a serious health issue.
In rare cases, an unexplained fever is linked to a specific and inherited genetic condition such asfamilial Mediterranean fever(FMF).Fevers with these conditions usually (but not always) begin in childhood. These disorders are typically not fatal but must be managed across a lifetime.Learn MoreWhat Are Periodic Fever Syndromes?
In rare cases, an unexplained fever is linked to a specific and inherited genetic condition such asfamilial Mediterranean fever(FMF).Fevers with these conditions usually (but not always) begin in childhood. These disorders are typically not fatal but must be managed across a lifetime.
Learn MoreWhat Are Periodic Fever Syndromes?
Yes. Pel-Ebstein is a fever that cycles every seven to 10 days or so. The fever rises abruptly, stays high for a week, falls, and then stays low for about a week. It’s not common, but a Pel-Ebstein fever pattern may be a symptom ofHodgkin lymphoma.Learn MorePel-Ebstein Fever Diagnosis and Patterns
Yes. Pel-Ebstein is a fever that cycles every seven to 10 days or so. The fever rises abruptly, stays high for a week, falls, and then stays low for about a week. It’s not common, but a Pel-Ebstein fever pattern may be a symptom ofHodgkin lymphoma.
Learn MorePel-Ebstein Fever Diagnosis and Patterns
Learn MoreSide Effects of Chemotherapy
11 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Unger M, Karanikas G, Kerschbaumer A, Winkler S, Aletaha D.Fever of unknown origin (FUO) revised.Wien Klin Wochenschr. 2016;128(21-22):796-801. doi:10.1007/s00508-016-1083-9Mulders-Manders C, Simon A, Bleeker-Rovers C.Fever of unknown origin.Clinical Medicine. 2015;15(3):280-284. doi: 10.7861/clinmedicine.15-3-280Hersch EC, Oh RC.Prolonged febrile illness and fever of unknown origin in adults.Am Fam Physician. 2014;90(2):91-96.Guo W, Feng X, Hu M, Shangguan Y, Xia J, Hu W, et al.The application of whole−exome sequencing in patients with fuo.Front Cell Infect Microbiol. 2022;0. doi: 10.3389/fcimb.2021.783568Foggo V, Cavenagh J.Malignant causes of fever of unknown origin.Clinical Medicine. 2015;15(3):292-294. doi: 10.7861%2Fclinmedicine.15-3-292Leukemia & Lymphoma Society.Signs and Symptoms.Cunha CB, Cunha BA.Fever of unknown origin(Fuo). In:Infectious Diseases. Elsevier; 2017:611-624.e2. doi: 10.1016/B978-0-7020-6285-8.00068-XStorck K, Brandstetter M, Keller U, Knopf A.Clinical presentation and characteristics of lymphoma in the head and neck region.Head Face Med. 2019;15(1):1. doi:10.1186/s13005-018-0186-0American Cancer Society.Signs and symptoms of non-Hodgkin lymphoma.National Organization of Rare Diseases.Familial Mediterranean Fever.Centers for Disease Control and Prevention.Watch Out for Fever.Additional ReadingAmerican Cancer Society.Signs and Symptoms of Cancer.Kouijzer IJ, Bleeker-Rovers CP, Oyen WJ.FDG-PET in fever of unknown origin.Seminars in nuclear medicine.2013;43(5):333-339. doi:10.1053/j.semnuclmed.2013.04.005
11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Unger M, Karanikas G, Kerschbaumer A, Winkler S, Aletaha D.Fever of unknown origin (FUO) revised.Wien Klin Wochenschr. 2016;128(21-22):796-801. doi:10.1007/s00508-016-1083-9Mulders-Manders C, Simon A, Bleeker-Rovers C.Fever of unknown origin.Clinical Medicine. 2015;15(3):280-284. doi: 10.7861/clinmedicine.15-3-280Hersch EC, Oh RC.Prolonged febrile illness and fever of unknown origin in adults.Am Fam Physician. 2014;90(2):91-96.Guo W, Feng X, Hu M, Shangguan Y, Xia J, Hu W, et al.The application of whole−exome sequencing in patients with fuo.Front Cell Infect Microbiol. 2022;0. doi: 10.3389/fcimb.2021.783568Foggo V, Cavenagh J.Malignant causes of fever of unknown origin.Clinical Medicine. 2015;15(3):292-294. doi: 10.7861%2Fclinmedicine.15-3-292Leukemia & Lymphoma Society.Signs and Symptoms.Cunha CB, Cunha BA.Fever of unknown origin(Fuo). In:Infectious Diseases. Elsevier; 2017:611-624.e2. doi: 10.1016/B978-0-7020-6285-8.00068-XStorck K, Brandstetter M, Keller U, Knopf A.Clinical presentation and characteristics of lymphoma in the head and neck region.Head Face Med. 2019;15(1):1. doi:10.1186/s13005-018-0186-0American Cancer Society.Signs and symptoms of non-Hodgkin lymphoma.National Organization of Rare Diseases.Familial Mediterranean Fever.Centers for Disease Control and Prevention.Watch Out for Fever.Additional ReadingAmerican Cancer Society.Signs and Symptoms of Cancer.Kouijzer IJ, Bleeker-Rovers CP, Oyen WJ.FDG-PET in fever of unknown origin.Seminars in nuclear medicine.2013;43(5):333-339. doi:10.1053/j.semnuclmed.2013.04.005
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Unger M, Karanikas G, Kerschbaumer A, Winkler S, Aletaha D.Fever of unknown origin (FUO) revised.Wien Klin Wochenschr. 2016;128(21-22):796-801. doi:10.1007/s00508-016-1083-9Mulders-Manders C, Simon A, Bleeker-Rovers C.Fever of unknown origin.Clinical Medicine. 2015;15(3):280-284. doi: 10.7861/clinmedicine.15-3-280Hersch EC, Oh RC.Prolonged febrile illness and fever of unknown origin in adults.Am Fam Physician. 2014;90(2):91-96.Guo W, Feng X, Hu M, Shangguan Y, Xia J, Hu W, et al.The application of whole−exome sequencing in patients with fuo.Front Cell Infect Microbiol. 2022;0. doi: 10.3389/fcimb.2021.783568Foggo V, Cavenagh J.Malignant causes of fever of unknown origin.Clinical Medicine. 2015;15(3):292-294. doi: 10.7861%2Fclinmedicine.15-3-292Leukemia & Lymphoma Society.Signs and Symptoms.Cunha CB, Cunha BA.Fever of unknown origin(Fuo). In:Infectious Diseases. Elsevier; 2017:611-624.e2. doi: 10.1016/B978-0-7020-6285-8.00068-XStorck K, Brandstetter M, Keller U, Knopf A.Clinical presentation and characteristics of lymphoma in the head and neck region.Head Face Med. 2019;15(1):1. doi:10.1186/s13005-018-0186-0American Cancer Society.Signs and symptoms of non-Hodgkin lymphoma.National Organization of Rare Diseases.Familial Mediterranean Fever.Centers for Disease Control and Prevention.Watch Out for Fever.
Unger M, Karanikas G, Kerschbaumer A, Winkler S, Aletaha D.Fever of unknown origin (FUO) revised.Wien Klin Wochenschr. 2016;128(21-22):796-801. doi:10.1007/s00508-016-1083-9
Mulders-Manders C, Simon A, Bleeker-Rovers C.Fever of unknown origin.Clinical Medicine. 2015;15(3):280-284. doi: 10.7861/clinmedicine.15-3-280
Hersch EC, Oh RC.Prolonged febrile illness and fever of unknown origin in adults.Am Fam Physician. 2014;90(2):91-96.
Guo W, Feng X, Hu M, Shangguan Y, Xia J, Hu W, et al.The application of whole−exome sequencing in patients with fuo.Front Cell Infect Microbiol. 2022;0. doi: 10.3389/fcimb.2021.783568
Foggo V, Cavenagh J.Malignant causes of fever of unknown origin.Clinical Medicine. 2015;15(3):292-294. doi: 10.7861%2Fclinmedicine.15-3-292
Leukemia & Lymphoma Society.Signs and Symptoms.
Cunha CB, Cunha BA.Fever of unknown origin(Fuo). In:Infectious Diseases. Elsevier; 2017:611-624.e2. doi: 10.1016/B978-0-7020-6285-8.00068-X
Storck K, Brandstetter M, Keller U, Knopf A.Clinical presentation and characteristics of lymphoma in the head and neck region.Head Face Med. 2019;15(1):1. doi:10.1186/s13005-018-0186-0
American Cancer Society.Signs and symptoms of non-Hodgkin lymphoma.
National Organization of Rare Diseases.Familial Mediterranean Fever.
Centers for Disease Control and Prevention.Watch Out for Fever.
American Cancer Society.Signs and Symptoms of Cancer.Kouijzer IJ, Bleeker-Rovers CP, Oyen WJ.FDG-PET in fever of unknown origin.Seminars in nuclear medicine.2013;43(5):333-339. doi:10.1053/j.semnuclmed.2013.04.005
American Cancer Society.Signs and Symptoms of Cancer.
Kouijzer IJ, Bleeker-Rovers CP, Oyen WJ.FDG-PET in fever of unknown origin.Seminars in nuclear medicine.2013;43(5):333-339. doi:10.1053/j.semnuclmed.2013.04.005
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