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Chemotherapy Side Effects
Chemotherapy (chemo) 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 chemo so you know what to watch for and can talk with your cancer care team about preventing and relieving them.
The side effects of chemo are different for each person. They depend on the type of cancer, location, types of chemo and dose, and your general health.
The information below describes side effects that might be caused by traditional or standard chemotherapy. There are also other medicines that are used to treat cancer in different ways, including targeted therapy, hormone therapy, and immunotherapy.
Why does chemo cause side effects?
Cancer cells grow fast, and chemo kills fast-growing cells. But because chemo travels throughout the entire body, it can affect normal, healthy cells that are fast-growing, too. Damage to healthy cells causes side effects. Side effects are not always as bad as you might expect, but it's normal to worry about this part of cancer treatment.
The normal cells most likely to be damaged by chemo are:
- Blood-forming cells in the bone marrow
- Hair follicles
- Cells in the mouth, digestive tract, and reproductive system
Some types of chemo can damage cells in the heart, kidneys, bladder, lungs, and nervous system.
Sometimes, you can take medicines with the chemo to help protect your body’s normal cells. There are also treatments to help relieve side effects.
Doctors try to give chemo at levels high enough to treat cancer while keeping side effects at a minimum. They also try to avoid using multiple types of chemo that have similar side effects.
What do I need to know about side effects?
- Every person doesn’t get every possible side effect, and some people get few or none.
- The severity of side effects (how bad they are) varies greatly from person to person.
- Your doctor may give you medicines to help prevent certain side effects before they happen.
- Some chemo causes long-term side effects, like heart or nerve damage or fertility problems. Still, many people have no long-term problems from chemo. Ask your doctor if the chemo you’re getting has long-term effects.
While side effects can be unpleasant, they must be weighed against the need to kill the cancer cells.
Be sure to talk to your cancer care team about:
- Which side effects are most common with your chemo
- How long they might last
- How severe they might be
- When and who to call if you have side effects
How long do chemo side effects last?
Many side effects are short-term. They go away fairly quickly after a chemo cycle, or they might last for as long as you are in treatment. But some might be long-term or chronic side effects. They start during treatment but continue even after treatment is over, sometimes lasting for months or years. Sometimes the side effects can last a lifetime, such as when chemo causes long-term damage to the heart, lungs, kidneys, or reproductive organs.
Certain types of chemo sometimes cause late side effects that start after treatment ends. These side effects can happen long after cancer treatment, such as a second cancer that may show up many years later.
People often become discouraged about how long their treatment lasts or the side effects they have. If you feel this way, talk to your cancer care team. They may be able to change your medicine or treatment schedule. Or they may suggest ways to reduce any pain and discomfort you have.
What are common side effects of chemo?
Side effects of chemo can be very different depending on the type you are getting. Here are some of the more common side effects caused by chemo:
- Fatigue
- Hair loss
- Thrombocytopenia (low platelet count)
- Neutropenia (low white blood counts)
- Increased risk of infection
- Anemia (low red blood cell counts)
- Nausea and vomiting
- Appetite changes
- Constipation
- Diarrhea
- Mouth sores
- Peripheral neuropathy or other nerve problems
- Skin and nail changes such as rash, dry skin and color change
- Bowel or bladder incontinence
- Weight changes
- Chemo brain, which can affect concentration and focus
- Anxiety
- Depression
- Changes in libido and sexual function
- Fertility problems
Learn more about these and other problems in Managing Cancer-related Side Effects.
Chemo drug interactions and side effects
When looking at how best to combine types of chemo, doctors must look at interactions between chemo drugs and other medicines the person is taking, including over-the-counter medicines, vitamins, and supplements. These interactions may make side effects worse and affect how well chemo works.
It’s important that you tell your doctor about all medicines, including over-the-counter medicines, vitamins, and herbal or dietary supplements you are taking—even if you only take them “as needed.”
For instance, platelets help blood clot and prevent bleeding. Many types of chemo lower the number of platelets for a time. Taking aspirin or other related medicines can also weaken blood platelets. This isn’t a problem for healthy people with normal platelet counts, but if a person has low platelet counts from chemo, this combination might put them at risk of a serious bleeding problem.
Your doctor can talk with you about the safety of using other medicines, vitamins, and supplements while you are being treated for cancer.
How vitamins affect chemo
Many people want to take an active role in improving their overall health. They want to help their body’s natural defenses fight the cancer and speed up their recovery from chemo. Most people think of vitamins as a safe way to improve health, so it’s not surprising that many people with cancer take high doses of one or more vitamins. But some vitamins might make chemo less effective.
More research is needed, but until more is known about the effects of vitamins on chemo, keep these points in mind:
- Unless your doctor tells you to take certain vitamins, it’s best not to take any.
- Always check with your doctor first before starting to take a vitamin of any kind, even a simple multivitamin.
- Ask your doctors if and when it might be OK to start taking vitamins after treatment.
- If you’re concerned about nutrition, you can usually get plenty of vitamins by eating a well-balanced diet. See Nutrition for People with Cancer to learn more about nutrition during and after cancer treatment.
When to call your cancer care team about chemo side effects
Because your cancer care team will give you lots of information about side effects, you might be more aware of physical changes. Do not take any physical symptoms you have lightly. Some side effects are short-lived and minor, but others may be a sign of serious problems. Make sure you know how to reach someone on your team any time, including after hours, weekends, and holidays.
Contact your cancer care team right away if you have any of the following symptoms:
- A fever higher than what your cancer care team has instructed (usually 100.5°F–101°F or higher, taken by mouth)
- Bleeding or unexplained bruising
- A rash
- An allergic reaction, such as swelling of the mouth or throat, severe itching, or trouble swallowing
- Intense chills
- Pain or soreness at the chemo injection site or catheter site
- Unusual pain, including intense headaches
- Shortness of breath or trouble breathing (If you’re having trouble breathing, call 911 first.)
- Long-lasting diarrhea or vomiting
- Bloody stool or blood in your urine
Ask your cancer care team if there are any other problems they should know about right away.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
American Society of Clinical Oncology. Side Effects of Chemotherapy? Accessed at cancer.net. Content is no longer available.
Anderson MK, Dickman E, Schmitt ML. Overview of cancer and cancer treatment. In: Olsen MM, LeFebvre KB, Walker SL, Dunphy EP, eds. Chemotherapy and Immunotherapy Guidelines and Recommendations for Practice. 2nd ed. Pittsburgh, PA: Oncology Nursing Society; 2023:29-52.
Gilson S. Chemotherapy. In Maloney-Newton S, Hickey M, Brant JM, eds. Mosby’s Oncology Nursing Advisor: A Comprehensive Guide to Clinical Practice. 3rd ed. St. Louis: Elsevier; 2024:388-408.
National Cancer Institute (NCI). Cancer therapy interactions with foods and dietary supplements (PDQ) – Health professional version. Updated April 5, 2024. Accessed at https://www.cancer.gov/about-cancer/treatment/cam/hp/dietary-interactions-pdq#_88 on April 22, 2025.
Olsen MM, Fritzsche D, O’Connor SL. Chemotherapy. In: Olsen MM, LeFebvre KB, Walker SL, Dunphy EP, eds. Chemotherapy and Immunotherapy Guidelines and Recommendations for Practice. 2nd ed. Pittsburgh, PA: Oncology Nursing Society; 2023:67-100.
Last Revised: May 15, 2025
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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