Side Effects of Chemotherapy

Approved by the Cancer.Net Editorial Board, 12/2021

Chemotherapy treats many types of cancer effectively. But like other cancer treatments, it often causes side effects. It is important to be aware of possible side effects from chemotherapy so you know what to watch for and can talk with your health care team about preventing and relieving them.

The side effects of chemotherapy are different for each person. They depend on the type of cancer, location, drugs and dose, and your general health.

Why does chemotherapy cause side effects?

Chemotherapy works by targeting active cells. Active cells are cells that are growing and dividing as a part of the normal cell cycle. Both cancer cells and healthy cells are active cells going through the cell cycle. Cancer cells typically grow faster than normal, healthy cells, which means it is easier for chemotherapy to attack the cancer cells. But some normal cells will be damaged by the chemotherapy as well. These include cells in your blood, mouth, digestive system, and hair follicles.

Side effects happen when chemotherapy damages these healthy cells. For example, you might lose your hair or experience nausea and vomiting.

For most types of chemotherapy, side effects do not show how well treatment is working.

Can side effects of chemotherapy be treated?

Yes. Your health care team can help prevent or treat many side effects. Today, many more medications are available to relieve side effects than in the past. Preventing and treating side effects is called palliative care or supportive care. It is an important part of cancer treatment at any stage.

Doctors and scientists are always working to develop drugs, drug combinations, and ways of giving treatment with fewer side effects. Many types of chemotherapy now bring less side effects than even a few years ago.

What are common side effects of chemotherapy?

The side effects you experience while on chemotherapy depend on which drug or combination of drugs are prescribed. Different drugs cause different side effects. And each person's experience is different. People may not experience the same side effects even when taking the same drug. And you can have different side effects than you did in the past if you take the same drug again.

That is why it is important to talk with your cancer care team regularly about the side effects you are worried about or are experiencing. Tell them about all the side effects you notice. It may be helpful to track side effects over time and share that information with your care providers.

Common side effects of chemotherapy include:

Fatigue. Fatigue is feeling tired or exhausted even if you get enough sleep. It is the most common side effect of chemotherapy. Learn about how to cope with fatigue.

Hair loss. Some types of chemotherapy, but not all, cause hair loss. Hair on your body may come out a little at a time or in large clumps. Hair loss usually starts after the first several weeks of chemotherapy. It tends to increase 1 to 2 months into chemotherapy. Your doctor can predict the risk of hair loss based on the drugs and doses you are receiving. Learn more about managing hair loss.

Pain. Chemotherapy sometimes causes pain. This can include:

Most types of pain related to chemotherapy get better or go away between individual treatments. However, nerve damage often gets worse with each dose. Sometimes the drug causing the nerve damage has to be stopped. It can take months or years for nerve damage from chemotherapy to improve or go away. In some people, it may cause permanent damage.

Treatment of any cancer-related pain will start by considering the cause. It is important to talk with your health care team about your pain levels during chemotherapy. There can be other reasons for pain besides the chemotherapy itself. If the pain is related to chemotherapy, doctors can treat it by:

  • Giving pain-relieving medications

  • Blocking pain signals from the nerves to the brain with spinal treatments or nerve blocks

  • Adjusting your dose of specific drugs

Learn more about cancer pain and how to manage it.

Mouth and throat sores. Chemotherapy can damage the cells inside the mouth and throat. This causes painful sores in these areas, a condition called mucositis. Mouth sores usually happen 5 to 14 days after a treatment. It is also important to watch for infection in these sores.

Eating a healthy diet and keeping your mouth and teeth clean can lower your risk of mouth sores. Mouth sores usually go away completely when treatment ends. Learn more about managing mucositis, including ways to relieve discomfort.

Diarrhea. Some chemotherapy causes loose or watery bowel movements. Preventing diarrhea or treating it early helps keep you from getting dehydrated (losing too much body fluid). It also helps prevent other health problems. Learn more about managing diarrhea.

Constipation. Chemotherapy can cause constipation. This means not having a bowel movement often enough or having difficult bowel movements. Other medicines, such as pain medication, can also cause constipation. You can lower your risk of constipation by drinking enough fluids, eating balanced meals, and getting regular exercise. Learn more about managing constipation.

Nausea and vomiting. Chemotherapy can cause nausea (feeling sick to your stomach) and vomiting (throwing up). Whether you have these side effects, and how often, depends on the specific drugs and dose. There are medications that are given before and after each dose of chemotherapy that can usually prevent nausea and vomiting. Learn more about nausea and vomiting.

Blood disorders. Your bone marrow is the spongy tissue inside your bones. It makes new blood cells. Chemotherapy affects this process, so you might have side effects from having too few blood cells.

Usually the number of blood cells return to normal after chemotherapy is complete. But during treatment, low numbers of blood cells can cause problems and must be watched closely. During chemotherapy, your doctor will routinely check your blood counts using 2 tests: complete blood count (CBC) and platelet count.

A CBC test shows the levels of red blood cells and white blood cells in your blood. Not enough red blood cells causes a condition called anemia. Symptoms include fatigue, dizziness, and shortness of breath. Not enough white blood cells causes a condition called leukopenia. This raises your risk of getting infections. When your white blood cells are low, getting an infection can be serious. If this happens, you need antibiotics as soon as possible.

A platelet count measures the number of platelets in your blood. Platelets are cells that stop bleeding. They do this by plugging damaged blood vessels and helping blood form clots. Not having enough platelets causes a condition called thrombocytopenia. You can bleed and bruise more easily than normal.

The doses of chemotherapy can often be adjusted to prevent low blood counts. Drugs are also available to treat these blood disorders. The drugs help your bone marrow make more blood cells. They can help prevent leukopenia in people with a high risk.

Nervous system effects. Some drugs cause nerve damage. This can cause the following nerve or muscle symptoms:

  • Tingling

  • Burning

  • Weakness or numbness in the hands, feet, or both

  • Weak, sore, tired, or achy muscles

  • Loss of balance

  • Shaking or trembling

  • Stiff neck or headache

  • Problems seeing, hearing, or walking normally

  • Feeling clumsy

These symptoms usually get better with a lower chemotherapy dose or after treatment. It can take 6 to 12 months for symptoms to get better after chemotherapy ends. Some side effects can be permanent. Learn more about managing nervous system side effects.

Changes in thinking and memory. Some people have trouble thinking clearly and concentrating after chemotherapy. Cancer survivors often call this chemobrain. Your doctor might call it cognitive changes or cognitive dysfunction. This condition usually improves or resolves after chemotherapy ends. Learn more about managing attention, thinking, and memory problems.

Sexual and reproductive issues. Chemotherapy can affect your fertility. Fertility is the ability to get pregnant and carry a pregnancy or to make someone else pregnant. If you want to have a child after cancer treatment, be sure to talk with your cancer care team about your options for fertility preservation before chemotherapy begins.

Being tired or feeling sick from cancer or treatment can affect your ability to enjoy sex. Talk with your doctor about these possible side effects before treatment starts. Learn more about managing sexual and reproductive side effects.

Some people might need a Pap test before starting chemotherapy. This is because chemotherapy can cause misleading results on the test. A Pap test gathers a sample of cells from the cervix.

Chemotherapy can also harm an unborn baby. This is especially true during the first 3 months of pregnancy, when the organs are still developing. If you could get pregnant during treatment, use effective birth control. If you do get pregnant, tell your doctor right away. Learn more about cancer during pregnancy.

Appetite loss. You might eat less than usual, not feel hungry at all, or feel full after eating a small amount. If this lasts through treatment, you may lose weight and not get the nutrition you need. You may also lose muscle mass and strength. All these things make it harder to recover from chemotherapy. Learn more about managing appetite loss.

Heart problems. Some types of chemotherapy can affect your heart. Ask your doctor if your heart will need testing before treatment. This way, doctors can tell if treatment causes problems later. One common test is an echocardiogram (echo). This test uses ultrasound waves to create a moving picture of the heart. Learn more about heart problems from cancer treatment.

Are some chemotherapy side effects permanent?

Most side effects go away after chemotherapy is complete. But some continue or come back, or develop later. For example, some types of chemotherapy may cause permanent damage to the heart, lungs, liver, kidneys, or reproductive system. And some people have trouble with thinking, concentrating, and memory for months or years after treatment. Cancer survivors also have a higher risk of second cancers later in life.

Children who had chemotherapy are at risk of specific side effects that happen months or years after treatment. Learn more about late effects in childhood cancer survivors.

Follow-up care after chemotherapy

Getting care after cancer treatment ends is important. Your health care team can help you treat long-term side effects and watch for late effects. This is called follow-up care. Your follow-up care might include regular physical examinations, medical tests, or both.

ASCO offers survivorship care plan forms to help you keep track of the cancer treatment you received and develop a clear follow-up plan after treatment. Be sure to ask your cancer care team for a survivorship care plan after your cancer treatment is complete, and share it with all future health care providers. This information will provides valuable details to them about how to best support your health throughout your life.

Questions to ask the health care team

Consider asking your health care team these questions:

  • What physical side effects are likely based on my specific chemotherapy plan? When will they likely begin?

  • How can these side effects be prevented or managed?

  • Who should I tell when a side effect appears or gets worse? How can I contact them during regular office hours and after hours?

  • Are there specific side effects I should tell the doctor about right away?

  • Would it be helpful for me to track my side effects? What are ways I can do that?

  • Who can I talk with if I'm feeling anxious or upset about having chemotherapy?

  • If I'm having side effects that affect my nutrition, can you recommend an oncology dietitian?

  • What are other ways I can take care of myself during the treatment period?

  • Could this treatment affect my sex life? If so, how and for how long?

  • Could this treatment affect my ability to become pregnant or have a child? If so, should I talk with a fertility specialist before cancer treatment begins?

  • What are the potential long-term effects of this type of chemotherapy?

  • If I'm worried about managing the financial costs of cancer care, who can help me?

  • After chemotherapy is completed, what will my follow-up care plan be?

Related Resources

What to Expect When Having Chemotherapy

Fear of Treatment-Related Side Effects

Understanding Chemotherapy (PDF; 2 pages)

How Symptom Tracking Makes Cancer Care Better

More Information

CancerCare: Understanding and Managing Chemotherapy Side Effects

National Cancer Institute: Chemotherapy and You

ASCO answers; Understanding Chemotherapy

Download ASCO's free 1-page fact sheets on Understanding Chemotherapy and Oral Chemotherapy. These printable PDFs provide an introduction to chemotherapy, answers to common questions, terms to know, and questions to ask the doctor.