People with cancer who are treated with chemotherapy are more likely to get infections because of their weakened immune system.

Chemotherapy works by stopping or slowing the growth of cancer cells, which grow and divide quickly. Chemotherapy kills fast-growing cancer cells. Chemotherapy also can damage your immune system by reducing your number of infection-fighting white blood cells. This makes it harder for your body to fight infections.

An infection can also lead to sepsis, the body’s extreme response to an infection. Sepsis happens when an infection you already have triggers a chain reaction throughout your body. It is a life-threatening medical emergency. If you or your loved one has an infection that’s not getting better or is getting worse, act fast.

Having cancer or having a history of cancer can make you more likely to get very sick from COVID-19 and the flu. Cancer and treatments for many types of cancer can weaken your body’s ability to fight off disease. Having a history of cancer may increase your risk.

What Is an Infection?

You get an infection when germs enter your body and multiply, causing illness, organ and tissue damage, or disease. Bacteria and viruses cause infections.

• You can get bacteria from the air, water, soil, or food during the course of your medical treatment. Most bacteria come from your own body. Common bacterial infections include pneumonia, urinary tract infections, and ear infections.
• Viruses are passed from one person to another. Common viral infections include the common cold, herpes, and the flu.

Why Does Chemotherapy Raise My Risk of Infections?

What Should I Do If I Think I Have an Infection?

Call your doctor right away, even if this happens in the middle of the night. This is considered an emergency. Don’t wait until morning. Always keep your doctor’s phone numbers with you. Make sure you know which number to call during your doctor’s office hours, as well as after hours.

What Can I Do to Protect Myself from an Infection?

If you get a fever during your chemotherapy treatment, it’s a medical emergency. Fever may be the only sign that you have an infection, and an infection during chemotherapy can be life-threatening.

You should take your temperature any time you feel warm, flushed, chilled, or not well. Call your doctor immediately if you have a temperature of 100.4ºF (38ºC) or higher.

You should also—

• Find out from your doctor when your white blood cell count is likely to the be the lowest, since this is when you’re most at risk for infection.
• Keep a working thermometer in a convenient location and know how to use it.
• Keep your doctor’s phone numbers with you at all times. Make sure you know what number to call when their office is open and closed.
• If you have to go to the emergency room, tell the person checking you in that you are a cancer patient undergoing chemotherapy. If you have a fever, you might have an infection. This is a life-threatening condition, and you should be seen quickly.

Clean hands help prevent infections. Many diseases are spread by not cleaning your hands, which is especially dangerous when you’re getting chemotherapy treatment because your body may not be able to fight off infections like it used to.

You and anyone who comes around you, including all members of your household, your doctors, and nurses, should clean their hands frequently. Don’t be afraid to ask people to clean their hands. Use soap and water to wash your hands. If soap and water aren’t available, it’s OK to use an alcohol-based hand sanitizer.

Be sure to clean your hands—

• Before, during, and after cooking food.
• Before you eat.
• After going to the bathroom.
• After changing diapers or helping a child use the bathroom.
• After blowing your nose, coughing, or sneezing.
• After touching or cleaning up after your pet.
• After touching trash.
• Before and after treating a cut or wound or caring for your catheter, port, or other access device.

During your chemotherapy treatment, your body may not be able to fight off infections like it used to. When your white blood cell counts are low, you must take infection symptoms seriously. Infection during chemotherapy can lead to hospitalization or death.

Call your doctor right away if you notice any of the following signs and symptoms of an infection—

• Fever (this is sometimes the only sign of an infection).
• Chills and sweats.
• Change in cough or a new cough.
• Sore throat or new mouth sore.
• Shortness of breath.
• Nasal congestion.
• Stiff neck.
• Burning or pain with urination.
• Unusual vaginal discharge or irritation.
• Increased urination.
• Redness, soreness, or swelling in any area, including surgical wounds and ports.
• Diarrhea.
• Vomiting.
• Pain in the abdomen or rectum.
• New onset of pain.

Find out from your doctor when your white blood cell count is likely to be the lowest, since this is when you’re most at risk for infection. This usually occurs between 7 and 12 days after you finish each chemotherapy dose, and may last up to one week.

What Is Neutropenia?

Neutropenia, pronounced noo-troh-PEE-nee-uh, is a decrease in the number of white blood cells. These cells are the body’s main defense against infection. Neutropenia is common after receiving chemotherapy and increases your risk for infections.

Why Does Chemotherapy Cause Neutropenia?

These cancer-fighting drugs work by killing fast-growing cells in the body—both good and bad. These drugs kill cancer cells as well as healthy white blood cells.

How Do I Know if I Have Neutropenia?

Your doctor or nurse will tell you. Because neutropenia is common after receiving chemotherapy, your doctor may draw some blood to look for neutropenia.

When Will I Be Most Likely to Have Neutropenia?

Neutropenia often occurs between 7 and 12 days after you receive chemotherapy. This period can be different depending upon the chemotherapy you get. Your doctor or nurse will let you know exactly when your white blood cell count is likely to be at its lowest. You should carefully watch for signs and symptoms of infection during this time.

How Can I Prevent Neutropenia?

There is not much you can do to prevent neutropenia from occurring, but you can decrease your risk for getting an infection while your white blood cell count is low.

Yes. Having cancer and undergoing certain treatments for cancer, such as chemotherapy, can put you at higher risk of developing an infection, and infections can lead to sepsis.

Chemotherapy works by killing the fastest-growing cells in your body—both good and bad. This means that along with killing cancer cells, chemo also kills your infection-fighting white blood cells.

When am I more likely to get an infection?

An infection or sepsis can happen at any time. However, when your body has very low levels of a certain type of white blood cell (neutrophils) that increases your risk of getting an infection. This condition is a common side effect of chemo called neutropenia.

How will I know if I have neutropenia?

Your doctor will routinely test for neutropenia by checking the level of your white blood cells.

How can I prevent an infection?

• Wash your hands often and ask others around you to do the same.
• Avoid crowded places and people who are sick.
• Talk to your doctor about getting a flu shot or other vaccinations.
• Take a bath or shower every day (unless told otherwise).
• Use an unscented lotion to try to keep your skin from getting dry or cracked.
• Clean your teeth and gums with a soft toothbrush.
• Use a mouthwash to prevent mouth sores (if your doctor recommends one).
• Do not share food, drink cups, utensils or other personal items, such as toothbrushes.
• Cook meat and eggs all the way through to kill any germs.
• Carefully wash raw fruits and vegetables.
• Protect your skin from direct contact with pet bodily waste (urine or feces).
• Wash your hands immediately after touching an animal or removing its waste, even after wearing gloves.
• Use gloves for gardening.

As a cancer patient, you may have received a lot of information about your treatment and your journey to recovery. Chemotherapy and radiation cause many changes in the body as they destroy cancer cells. One major change is that these treatments weaken your immune system, which can increase your chances of getting an infection, including a fungal infection.

Stem cell transplant patients or those who have a blood (hematologic) cancer such as leukemia, lymphoma, or myeloma may have different risks for fungal infections.

What you need to know about fungal infections

Chemotherapy and radiation lower your white blood cell count. As you receive your cancer treatment, your white blood cell count can become very low, also known as neutropenia. During this time, your body will have trouble fighting infections, including fungal infections.

Fungal infections can range from mild to life-threatening. Some fungal infections are mild skin rashes, but others can be deadly, like fungal pneumonia. Because of this, it’s important to seek treatment as soon as possible to try to avoid serious infection.

Fungal infections can look like bacterial or viral infections. If you’re taking medicine to fight an infection and you aren’t getting better, ask your doctor about testing you for a fungal infection.

The type of cancer you have can affect your risk. If you have a blood cancer like leukemia or myeloma, you may be at greater risk for getting a fungal infection than people with other types of cancer.

Your risk of infection can change based on the strength of your chemotherapy. Some types of cancer may require stronger chemotherapy medication than others, especially the blood cancers. This is sometimes known as aggressive chemotherapy. Aggressive chemotherapy weakens your immune system and can put you at risk for getting a fungal infection.

Your hospital stay matters. After your transplant, you may need to stay in the hospital for a long time. While there, you may need to have procedures that can increase your chance of getting a fungal infection.

Where you live (geography) matters. Some disease-causing fungi are more common in certain parts of the world. If you live in or visit these areas and have cancer, you may be more likely to get these infections than the general population.

Preventing fungal infections in cancer patients

Fungi are difficult to avoid because they are a natural part of the environment. Fungi live outdoors in soil, on plants, trees, and other vegetation. They are also on many indoor surfaces and on your skin. However, there may be some ways for you to lower the chances of getting an infection, including a serious fungal infection.

Learn about fungal infections. There are different types of fungal infections. Learning about them can help you and your healthcare provider recognize the symptoms early, which may prevent serious illness.

Know if your white blood cell count is low. Having a very low white blood cell count (neutropenia) can put you at greater risk of infection.

Get additional medical care if necessary. Fungal infections often resemble other illnesses. Visiting your healthcare provider may help with faster diagnosis and may prevent serious illness.

Antifungal medication. Your healthcare provider may prescribe medication to prevent fungal infections. Scientists are still learning about which patients are at highest risk and how to best prevent fungal infections.

Protect yourself from the environment. As you recover from chemotherapy and start doing your normal activities again, there may be some ways to lower the chances of getting a serious fungal infection by trying to avoid disease-causing fungi in the environment. It’s important to note that although these actions are recommended, they have not been proven to prevent fungal infections.

• Try to avoid areas with a lot of dust like construction or excavation sites.
• Stay inside during dust storms.
• Stay away from areas with bird and bat droppings. This includes places like chicken coops and caves.
• Wear gloves when handling materials such as soil, moss, or manure.
• Wear shoes, long pants, and a long-sleeved shirt when doing outdoor activities such as gardening, yard work, or visiting wooded areas.

What is coronavirus, or COVID-19?

Coronaviruses are a large family of viruses that are common in people and many different species of animals. CDC is responding to an outbreak of respiratory disease caused by a novel (new) coronavirus that was first detected in China and has now been detected in the United States and many other countries. The virus has been named SARS-CoV-2, and the disease it causes has been named coronavirus disease 2019, which is abbreviated COVID-19.

This is a rapidly evolving situation and the risk assessment will be updated as needed.

If I have cancer, am I at higher risk of getting or dying from COVID-19?

Some types of cancer and treatments such as chemotherapy can weaken your immune system and may increase your risk of any infection, including with SARS-CoV-2, the virus that causes COVID-19. During chemotherapy, there will be times in your treatment cycle when you are at increased risk of infection.

Adults and children with serious chronic health conditions, including cancer, are at higher risk of developing more serious complications from contagious illnesses such as COVID-19.

If I have cancer, how can I protect myself?

There is currently no vaccine to prevent COVID-19 or specific treatment for it. The best way to prevent illness is to avoid being exposed to the virus. Precautions for avoiding COVID-19 are the same as for other contagious respiratory illnesses, such as influenza (flu).

The US Centers for Disease Control and Prevention (CDC) recommends everyday preventive measures to help prevent the spread of respiratory infections, including:

• Avoid large social gatherings and close contact with people who are sick
• Avoid unnecessary person-to-person contact, such as handshakes
• Avoid touching your eyes, nose, and mouth
• Wash your hands often with soap and water for at least 20 seconds, especially after going to the bathroom; before eating; after blowing your nose, coughing, or sneezing; and before and after coming in contact with others
• Get a flu vaccine

CDC recommends additional actions to help keep people at high risk for developing serious complications from COVID-19 healthy in the event of a COVID-19 outbreak in your community, including:

• Stay home as much as possible
• Make sure you have access to several weeks of medication and supplies in case you need to stay home for prolonged periods of time
• When you do go out in public, avoid crowds
• Avoid cruise ship travel and nonessential air travel

NCI provides tips and resources for the cancer community to prepare for any emergency.

I receive cancer treatment at a medical facility. What should I do about getting treatment?

Call your health care provider and follow their guidance.

I participate in a clinical trial at a medical facility. What should I do?

Call your clinical trial research team and follow their guidance.

What should I do if I have symptoms of an infection?

Call your health care provider if you think you have been exposed to COVID-19 and have symptoms of an infection.

Everyone 6 months of age and older should get a flu vaccine every season.

Flu vaccination is especially important for people with cancer or a history of cancer because they are at high risk of developing serious flu complications.

Are Cancer Patients and Survivors More Likely to Get the Flu Than Others?

We don’t know this specifically. But we do know that cancer may increase your risk for complications from the flu. If you have cancer now or have had certain types of cancer in the past (such as lymphoma or leukemia), you are at higher risk for complications from the flu.

Should Cancer Patients and Survivors Get a Flu Shot?

Yes. Injectable influenza vaccines (or flu shots) are approved for use in people with cancer and other health conditions. The flu shot has a long, established safety record in people with cancer.

People who live with or care for cancer patients and survivors also should be vaccinated against seasonal flu.

Flu Shots for Older Adults

Some older adults (65 years of age and older) may have a weaker immune response to flu vaccines. This can make them more likely to get the flu or flu complications.

Two vaccines are designed to create a stronger immune response in people who are 65 or older—

• The high-dose flu vaccine contains four times the amount of antigen as the regular flu shot.
• The adjuvanted flu vaccine contains an additive (called adjuvant).

For more information, see People 65 Years and Older and Influenza.

You May Need a Pneumococcal Shot, Too

Having the flu increases a person’s risk for pneumococcal disease. Pneumococcal pneumonia is a serious flu-related complication that can cause death. People with cancer or other diseases that compromise the immune system should ask their doctor about pneumococcal shots.

Make a plan in advance with your doctor about what to do if you get sick. Flu-like symptoms also can be a sign of a very serious infection that is not the flu. The plan includes when you should call your doctor and how to get a prescription for antiviral medication quickly if needed.

What to Do If You Get Sick

If you have flu symptoms—

• Stay home for at least 24 hours after your fever is gone except to get medical care or for other necessities. Your fever should be gone without the use of a fever-reducing medicine.
• Keep away from others as much as possible to avoid making them sick.

It’s important for people with cancer to call their doctor immediately if they get a fever. If you get a fever during your chemotherapy treatment, it’s a medical emergency.

Antiviral Drugs

CDC recommends antiviral drugs to treat flu illness, if your doctor prescribes them. If you get sick, antiviral drugs can make your illness milder and shorten the time you are sick. They may also prevent serious flu complications.

It’s very important that antiviral drugs be used promptly to treat flu in people who are very sick with flu (for example, people who are in the hospital) and people who are sick with flu and have a greater chance of getting serious flu-related complications, including cancer patients.

Call your doctor immediately and ask if you should receive antiviral drugs if you have been within six feet of someone known or thought to have the flu and—

• You have received cancer treatment such as chemotherapy or radiation therapy within the last month, or
• You have a blood or lymphatic form of cancer.

Vaccines are especially critical for people with health conditions such as a weakened immune system.

If you have cancer or other immunocompromising conditions, talk with your doctor about:

• Influenza vaccine each year to protect against seasonal flu
• Tdap vaccine to protect against whooping cough and tetanus
• Pneumococcal vaccine (both types) to protect against pneumonia and other pneumococcal diseases
• HPV vaccine series to protect against human papillomavirus if you are a man or woman up to age 26 years