Fever can be a sign that your immune system is doing its job: protecting you. It’s the body’s way of letting you know that something is wrong.

When you have leukemia, there are many different possible causes of fever. It can be a normal symptom of leukemia itself. Cancer treatment and its side effects can also cause a fever. However, fever could indicate that you have an infection, which could become life-threatening quickly without treatment.

About Fever

Body temperature is controlled by the hypothalamus — a part of the brain that manages many different body processes. Throughout the day, most people’s temperatures rise and fall within a certain range. This may happen for various reasons, such as physical activity, excitement, or changes in the temperature of your surrounding environment. A temperature above the normal range, a fever, is an indication that something is wrong. When a person’s body temperature rises above 100.4 degrees Fahrenheit, they are said to have a fever.

The average person’s “normal” body temperature ranges from around 97 F to 99 F. Infants and young children have a slightly different normal body temperature (95.9 F to 99.5 F), as do adults older than 65 (96.4 F to 98.5 F).

When Is Fever a Normal Part of Leukemia?

Fevers are often a regular part of life with leukemia. With leukemia, including pediatric (childhood) leukemia, fevers tend to occur more frequently and can mean several different things. When you have leukemia, fever can be a cancer symptom, a treatment side effect, or a sign of another health condition.

Fever as a Leukemia Symptom

Fever is a rare symptom of leukemia itself. Leukemia cells may be able to cause a temperature elevation, but most fevers seen in leukemia are caused by infections.

Fever as a Leukemia Treatment Side Effect

Some leukemia treatments can also cause fever. Certain treatments — such as chemotherapy and radiation therapy — are so harsh and toxic that they activate the immune system. In fact, cancer treatment can cause a flu-like syndrome.

Chemotherapy and radiotherapy can decrease levels of a specific type of immune cell called a neutrophil. A person with low neutrophil counts is said to have neutropenia. The fever associated with this dangerous condition is called neutropenic fever. People with neutropenia are at much higher risk for developing infections.

Some targeted therapies used to treat cancer have also been shown to cause fever as a side effect.

When Should You Be Concerned About Fever?

If you’re living with leukemia, you should take fevers seriously. A leukemia-suppressed immune system makes a person more susceptible to bacterial infections, fungal infections, and viral infections. Infections can progress or worsen much more quickly in leukemia survivors.

Fever as a Sign of Serious Health Conditions

Deep vein thrombosis (DVT), a type of venous thromboembolism, is a health condition in which a blood clot forms in a deep vein, most often a leg. Fever is among the symptoms of DVT. Other symptoms include:

• Muscle pain or aching
• Soreness
• Swelling
• Redness in a leg or arm

DVT is potentially life-threatening, as a blood clot could travel to other parts of the body and create a blockage in the veins of the heart and lungs. People with leukemia are at greater risk of DVT, especially among those who undergo stem cell transplants.

Fever as a Response to Infection

Fever is usually a sign that there is an infection in the body. Some infections can be life-threatening when your immune system has been weakened. With leukemia, even a common cold could be cause for concern.

Seek guidance from your general physician or your leukemia treatment team if you have a fever accompanied by any of the following symptoms of infection:

• Earache
• Runny nose
• Sinus pressure
• Sore throat
• Swelling or redness around an injured body part
• Tooth pain

When Is a Fever an Emergency?

If you have a fever accompanied by any of the following symptoms, you should seek immediate medical care, day or night:

• A persistent temperature of 100.4 F or higher
• Shaking or chills
• Blood in vomit or stool, which may indicate bleeding within the digestive system
• Breathing (respiratory) problems (e.g., shortness of breath, wheezing, difficulty breathing, or the inability to breathe), which could indicate pneumonia or something more serious
• Chest pain or pressure, heart palpitations, increased or irregular heart rate (tachycardia), which could indicate a serious cardiac (heart) problem such as a heart attack
• Cognitive or behavior changes (e.g., confusion, delusions, or hallucinations), which could indicate severe toxicity (sepsis) or a dangerously high fever
• Pus or excessive bruising at the site of an injury, catheter, port, or surgical incision
• Seizure or loss of consciousness
• Severe headache accompanied by a stiff neck, which could indicate meningitis
• Severe pain or pain that comes on suddenly, is long-lasting, or doesn’t respond to your pain management regimen
• Skin rash, which could be an indication of various issues, including an allergic reaction or an infectious disease
• Frequent urination, not urinating, or blood in the urine, which may indicate a kidney or urinary tract infection

Preventing Infections

As a general rule, preventing infections (and fever) is better than having to manage a fever. To minimize your risk of infection:

• Wash or sanitize your hands thoroughly and frequently.
• Make hygiene a priority. This includes keeping your catheter, port, and surgical sites clean and dry, brushing your teeth thoroughly, and cleaning any cuts or scrapes.
• Minimize contact with people who may be sick. This includes avoiding crowds and not sharing food, beverages, or utensils.
• Follow food safety guidelines and cook your food all the way through.

What Is the Best Way To Manage a Fever?

With leukemia, it's better to be safe than sorry. If you have a fever or any symptoms of a possible infection, you should get in touch with your health care provider. Your doctor may conduct blood tests, chest X-rays, or other diagnostic tests to find out what is causing your fever. It's important for your doctor to confirm the underlying cause of your fever, and swiftly, so they can recommend proper treatment.

Low-grade fevers can be managed with over-the-counter medications like acetaminophen, ibuprofen, and naproxen. However, you should not take any medications to control your fever without clearance from your physician.

Some at-home tactics and tips for dealing with fever include the following:

• Take your temperature often (every two to three hours) and record your symptoms. This is vital information for your doctor and can help inform your swift diagnosis.
• Stay hydrated when you have a fever. Drink plenty of clear liquids, including water, sports drinks (for the electrolytes), and broth.
• Apply a cold compress or damp cloth to your forehead, or take a lukewarm shower or bath. This may help lower your core temperature.

Talk With Others Who Understand

MyLeukemiaTeam is the social network for people with leukemia and their loved ones. On MyLeukemiaTeam, more than 10,000 members come together to ask questions, give advice, and share their stories with others who understand life with leukemia.

Have you experienced fever while living with leukemia? Share your experiences in the comments below, or start a conversation by posting on your Activities page.