Side Effects of Cancer Treatment
A plain-language overview of why cancer and its treatment cause side effects, and why speaking up helps your team manage them, based on National Cancer Institute resources.
Source: National Cancer Institute · Verified 2026-07-02
5 min readBeginnerUpdated 2026-07-02
The 30-second version
Cancer and cancer treatments can cause side effects—problems that happen when treatment affects healthy tissues or organs. Side effects vary from person to person, even among people getting the same treatment. Your health care team can treat many side effects or help you reduce them, so it helps to speak up about any problems you have.
Key takeaways
- Side effects are problems that occur when treatment affects healthy tissues or organs.
- Both the cancer itself and cancer treatments can cause side effects.
- Side effects vary from person to person, even among people getting the same treatment.
- Your health care team can treat many side effects or find ways to reduce them.
- Telling your doctor about side effects helps you get the care you need to feel better.
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The full explanation.
The simple version
Cancer treatments and cancer itself can cause side effects. A side effect is a problem that happens when treatment affects healthy tissues or organs—not just the cancer cells. Because treatment can reach normal parts of the body, it can sometimes cause new problems while it works against the cancer.
The most important thing to know: your health care team can help. They can treat many side effects, or talk with you about ways to reduce them, so you feel better.
Why side effects happen
Cancer treatments are designed to destroy or slow cancer cells. But healthy cells and organs can also be affected along the way. When that happens, you may notice problems such as tiredness, an upset stomach, or changes in how you eat. These are side effects.
The cancer itself can also cause problems that feel like side effects, so the two can overlap.
Side effects are different for everyone
Keep in mind that side effects vary from person to person, even among people receiving the same type of cancer treatment. You might have side effects that a friend or family member with cancer never had, and the opposite can be true too. There is no single way that treatment affects everyone.
Because of this, it helps to focus on your own experience rather than comparing yourself with others.
Speak up so your team can help
Tell your doctor about side effects you are experiencing, so you get the care and treatment you need to manage these problems. Speaking up early is one of the most helpful things you can do.
Your health care team can:
- treat the side effect directly
- suggest ways to prevent it or make it less severe
- adjust your care so you feel better day to day
You do not have to simply "put up with" side effects—reporting them is part of good care.
Common side effects to learn about
There are many possible side effects, and which ones you may have depends on your treatment and your body. Some of the ones NCI describes include:
- fatigue (extreme tiredness)
- hair loss (alopecia)
- nausea and vomiting
- pain
- appetite loss and weight changes
- anemia (too few red blood cells)
- infection
- constipation, diarrhea, and other digestion problems
- mouth and throat problems
- nerve problems
- skin and nail changes
- sleep problems
Learning what to expect can make side effects feel less frightening and help you know when to reach out to your team.
Watch instead
Animated lessons are in production. Here’s the planned video slate for this topic — each one will be based on the same NCI-sourced explanation you’re reading.
Side Effects of Cancer Treatment: the quick overview
A one-breath explanation you can watch before an appointment.
Coming soonSide Effects of Cancer Treatment, explained simply
The core ideas with friendly animation and plain language.
Coming soonUnderstanding side effects of cancer treatment — full lesson
A deeper walkthrough covering the key takeaways and common questions.
Coming soonVideo transcript▾
A full, readable transcript will appear here when the video is published — so the lesson is accessible whether you prefer to watch, listen, or read. For now, the article above is the complete text version.
Suggested animation storyboard▾
- 1Open on a calm title card: "Side Effects of Cancer Treatment" with the Cancer Explained mark.
- 2Narrator reads the 30-second summary while a soft animated diagram builds on screen: "Cancer and cancer treatments can cause side effects—problems that happen when treatment affects healthy tissues or organs. Side effects vary from person to person, even among people getting the same treatment. Your health care team can treat many side effects or help you reduce them, so it helps to speak up about any problems you have."
- 3Scene 2: illustrate the idea — "Side effects are problems that occur when treatment affects healthy tissues or organs."
- 4Scene 3: illustrate the idea — "Both the cancer itself and cancer treatments can cause side effects."
- 5Scene 4: illustrate the idea — "Side effects vary from person to person, even among people getting the same treatment."
- 6Close on a reminder card: this is educational only; talk with your healthcare team, and a link to the NCI source.
Words to know
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Quick knowledge check
According to this article, what is a side effect?
Frequently asked questions
▸What is a side effect?
A side effect is a problem that occurs when treatment affects healthy tissues or organs, not just the cancer. Cancer treatments and cancer itself can both cause side effects.
▸Will I get the same side effects as someone else with my type of cancer?
Not necessarily. Side effects vary from person to person, even among people receiving the same type of cancer treatment. Your experience may be different from someone else's.
▸Should I tell my doctor about side effects, or try to deal with them myself?
Speak up about any problems you have. Your health care team can treat side effects and talk with you about ways to reduce them, so you feel better. Telling your doctor helps you get the care you need.
▸What kinds of side effects can cancer treatment cause?
Many kinds. NCI lists side effects that range from fatigue, hair loss, nausea and vomiting, and pain to appetite and weight changes, anemia, infection, nerve problems, and more. Which ones you may have depends on your treatment and your body.
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Questions to ask your healthcare team
Consider bringing these questions to your next appointment.
- What side effects are most likely with the treatment I'll be receiving?
- When might these side effects start, and how long could they last?
- Which side effects should I call you about right away?
- What can be done to prevent or reduce these side effects?
- Who on my care team should I contact when a side effect bothers me?
- Are there side effects that could become serious if I don't report them?
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