Is a Persistent Low-Grade Fever a Symptom of Cancer?

A fever is a common symptom that's related to many conditions, most of which are benign. An increase in body temperature is most often a biological response to a viral or bacterial infection (like the flu or strep throat).

According to the Centers for Disease Control (CDC), a person has a fever when they have a temperature of 100.4 F or greater. A temperature of 99.6 F to 100.3 F is considered a low-grade fever. A high-grade fever is greater than 103 F. Hyperpyrexia is a fever higher than 106.7.

The body raises its temperature to help destroy the invading germ. But what if you're not fighting off a cold? In some cases, a persistent and otherwise unexplained fever ​can be a symptom of cancer. ​​

This article explains fevers related to cancer, symptoms, and other conditions that may cause low-grade fevers.

Fever and Cancer

Leukemia and ​lymphoma are two types of cancer that are commonly known to cause fevers.

• Leukemia is a cancer of the blood-forming tissues in the body. Unexplained fevers are one of the symptoms of leukemia. However, it isn't usually an isolated symptom. Other symptoms include fatigue, enlarged lymph nodes, unexplained bruising, body pains, and weight loss.
• Lymphoma is a cancer of the lymphatic system (which is part of the immune system). One type is called Hodgkin disease, and the other types are called non-Hodgkin lymphomas. Symptoms of lymphoma include fever, swollen lymph nodes, night sweats, loss of appetite, fatigue, and shortness of breath.

Signs and Symptoms

These are the three key signs of a cancer-related fever:

• It's a persistent fever, meaning it lasts longer than three days.
• It can be either a low- or high-grade fever.
• Other symptoms can accompany it, or it can occur without other symptoms.

Keep an eye on your temperature regularly by using a thermometer. Even if over-the-counter (OTC) fever reducers like acetaminophen or ibuprofen relieve your fever, it's still critical to see your healthcare provider if the fever lasts for more than three days.

Other Causes of Fevers

Fever as a sign of cancer is rare. Many things unrelated to cancer can lead to fevers. The most common cause of fevers is infections. Viruses, bacteria, parasites, and other pathogens commonly result in fevers as the body works to fight the infection.

Infections that lead to fevers include:

• Bone infections (Osteomyelitis)
• Appendicitis
• Skin infections
• Meningitis
• Colds
• Flu
• Ear infections
• Sinus infections
• Mononucleosis (mono)
• Strep throat
• Bronchitis
  
• Pneumonia
• Tuberculosis (TB)
• Urinary tract infections (UTIs)
• Gastroenteritis (stomach flu)

In addition to infections, fevers may also be caused by:

• Medications
• Heat
• Autoimmune diseases, like arthritis, lupus, and multiple sclerosis (MS)
• Vaccines

At Your Appointment

Since many conditions can cause unexplained fevers, your healthcare provider will likely ask many questions to help make an accurate diagnosis. Be prepared to answer the following:

• How long have you had a fever?
• Do you have any other symptoms?
• What medications are you taking?
• Do you have any diseases or health conditions?
• How often do you have a fever? Do you notice it more at night?
• Do you have a dental abscess or other dental problems that may have an infection?
• Have you traveled to any other countries within the last few months?

Your healthcare provider may decide to do a few routine tests to help pinpoint the source of your fever. These might include:

• Complete blood count (CBC), a blood test that measures your blood cells
• Chem 7 panel, a blood test that looks at seven different substances in the blood, including blood urea nitrogen (BUN) carbon dioxide, creatinine, glucose, serum chloride, serum potassium, and serum sodium
• Urinalysis to rule out a urinary tract infection

Summary

Rarely, unexplained fevers may be a symptom of cancer. For example, leukemia and lymphoma are two types of cancer that can present with fevers. Most commonly, though, fevers indicate an infection.

A Word From Verywell

Keep in mind that a fever is a very general, vague symptom of cancer. It's not a red flag, but it does indicate something is going on.

If you have had a fever for more than a few days, it's a good idea to see your doctor. They will run specific medical tests that can help pinpoint the source of the fever.