Approved by the Cancer.Net Editorial Board, 02/2020

An infection happens when your body's immune system is unable to fight off bacteria, viruses, and other pathogens. A pathogen, commonly called a germ, causes illness.

Your immune system is your body's way of fighting pathogens. It is a process that involves cells, organs, and proteins. When your immune system is working properly, white blood cells destroy harmful germs. When it is weak, your white blood cells have a harder time fighting infection.

Cancer and its treatment can make your immune system weaker and lower your level of certain white blood cells. If you have cancer and are currently in treatment for cancer, you are more likely to get infections.

Infections are treatable, but they can be serious and life-threatening. Talk with your health care team if you experience signs of an infection or changes in your symptoms.

What are the signs of an infection?

You can get an infection almost anywhere in your body. Some common places include your mouth, skin, and lungs. Infections can also be common in the urinary tract, the rectum, and the genitals.

Signs of an infection include:

  • Fever – Body temperature of 100.5°F (38°C) or higher

  • Chills or sweating

  • Mouth, throat sores, or a toothache

  • Abdominal (belly) pain

  • Pain near the anus – you may also have sores or diarrhea

  • Pain or burning when you urinate or having to urinate often

  • A cough or difficulty breathing normally

  • Redness, swelling, or pain, especially around a cut or where you had surgery or a catheter

  • Itching in the vagina, sometimes with a discharge

Doctors can treat infections. But they can be serious, and some can even cause death. Getting treatment right away is important.

Treating infections is an important part of cancer care. Treatment for side effects of cancer or treatment is called palliative care or supportive care. Talk with your health care team if you think you might have an infection.

What are the risk factors for getting an infection?

Certain things make your immune system weaker. They include things from everyday life, such as stress, sleep problems, and not eating well. Some cancer treatments also raise your risk of getting infections. These include:

  • Chemotherapy and other cancer medicines

  • Radiation therapy to large areas of the body, including the pelvis, legs, chest, or belly

  • Surgery

  • Bone marrow/stem cell transplantation

Certain cancers, cancer stages, and health conditions can also raise your risk. These include:

  • Cancers that affect the bone marrow, such as leukemia and lymphoma

  • Cancers that have spread to the bone

  • Other health conditions, such as diabetes, kidney disease, high blood pressure, congestive heart failure, liver disease and chronic obstructive pulmonary disease, or COPD

How is an infection treated?

Your doctor might prescribe antibiotics or other medications if your cancer treatment raises your infection risk. Sometimes these medications are given to prevent infections. You may receive medication after you have signs and symptoms of an infection.

If your level of certain white blood cells called neutrophils goes too low and you have a fever, you may need to stay in the hospital. A too-low level of neutrophils is called neutropenia. Learn more about neutropenia and how it is managed.

How can infection be prevented?

You can do many things to help prevent infections. You can:

  • Wash your hands well and often, especially after using the bathroom and before eating. You can also use hand sanitizers.

  • Take a shower or bath every day.

  • Use lotion to prevent dry and cracked skin.

  • Use gloves when you garden or do housework, especially while cleaning.

  • Wash fruits and vegetables well. Learn more about food safety.

  • Clean your teeth and gums with a soft toothbrush. Use mouthwash to prevent infections if your doctor or dentist recommends it. Learn more about dental health during cancer treatment.

  • Get a flu shot each fall.

You can also avoid things that might lead to an infection. Avoid:

  • Being near sick people.

  • Using someone else's cup, eating utensil, or toothbrush, or sharing food or makeup.

  • Eating raw meat, seafood, and eggs.

  • Using scissors, knives, and other sharp objects. If you must use them, be very careful. To avoid cuts, consider using an electric shaver and a blunt nail file instead of nail clippers.

  • Handling cat litter and other animal waste.

Questions to Ask Your Health Care Team About Infections

  • Am I at an increased risk of infection? If so, for how long?

  • Are there things I can do to help prevent infections?

  • What are the signs or symptoms of an infection I should watch for?

  • If I think I have an infection, how soon should I let you know?

Related Resources

When to Call the Doctor During Cancer Treatment

Side Effects of Chemotherapy

Side Effects of Immunotherapy

Side Effects of Radiation Therapy

Side Effects of Surgery

Side Effects of Bone Marrow/Stem Cell Transplantation

More Information

National Cancer Institute: Infection and Neutropenia during Cancer Treatment

Centers for Disease Control and Prevention: Preventing Infections in Cancer Patients