Chemo Brain: Memory and Concentration Problems
A plain-language explanation of memory and concentration problems during cancer treatment—often called chemo brain—and ways to manage them, based on National Cancer Institute resources.
Source: National Cancer Institute · NCI reviewed 2023-01-26 · Verified 2026-07-02
The 30-second version
Some cancer treatments can make it harder to think, concentrate, or remember things. People sometimes call this mental fog or chemo brain. It can start during or after treatment, and it ranges from very small changes to much greater problems. Your doctor can assess your symptoms and suggest ways to manage or treat them.
Key takeaways
- Memory or concentration problems—sometimes described as a mental fog or chemo brain—can be a side effect of cancer treatment.
- Chemotherapy, some types of radiation therapy to the brain, and immunotherapy may cause difficulty with thinking, concentrating, or remembering.
- Whether these problems happen depends on the type of treatment you receive, your age, and other health-related factors.
- They may start during or after treatment, and they range from very small changes to much greater problems.
- Planning your day, exercising your body and mind, and using written lists or planners can help you manage minor problems.
- Tell your health care team about any memory or thinking changes—your doctor can assess your symptoms and advise you.
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The full explanation.
The simple version
Some cancer treatments can make it harder to think, concentrate, or remember things. People sometimes describe this as a mental fog, or call it chemo brain.
These problems are a known side effect of cancer treatment—and there are ways to manage them. Whether you have memory or concentration problems depends on the type of treatment you receive, your age, and other health-related factors.
Which treatments can cause it
Cancer treatments such as chemotherapy may cause difficulty with thinking, concentrating, or remembering things. So can some types of radiation therapy to the brain, and immunotherapy.
These cognitive problems may start during or after cancer treatment. And they don't look the same for everyone. Some people notice very small changes, such as a bit more difficulty remembering things. Others have much greater memory or concentration problems.
What your doctor can do
Your doctor will assess your symptoms and advise you about ways to manage or treat these problems.
Other conditions can play a part, too. Treating conditions such as poor nutrition, anxiety, depression, fatigue, and insomnia may also help with memory and concentration.
That's one reason it's so important to speak up. It's important for you—or a family member—to tell your health care team if you have difficulty remembering things, thinking, or concentrating.
Ways to manage memory or concentration problems
For minor memory or concentration problems, there are practical steps you can take:
- Plan your day. Do the things that need the most concentration at the time of day when you feel best. Get extra rest and plenty of sleep at night. If you need to rest during the day, short naps of less than an hour are best—long naps can make it harder to sleep at night. Keep a daily routine.
- Exercise your body and mind. Exercise can help decrease stress and help you feel more alert. It releases endorphins—"feel-good chemicals" that give people a feeling of well-being. Ask your team what light physical exercises may be helpful for you. Mind–body practices such as meditation, or mental exercises such as puzzles and games, also help some people.
- Get help to remember things. Write down important information and keep the list handy. Use a daily planner, recorder, or other electronic device to help you remember important activities. Make a list of important names and phone numbers, and keep it in one place so it's easy to find.
Talking with your health care team
It's important for you or a family member to talk with your doctor or nurse about any memory or cognitive changes you notice. Prepare for your visit by making a list of questions to ask ahead of time—the "Questions to ask your healthcare team" list on this page is a good starting point.
Your team can also connect you with more support. You might ask to meet with a social worker for ideas about additional support and resources, or ask whether specialists—such as a neuropsychologist, an occupational therapist, or a vocational therapist—could assess, treat, or advise you on these problems.
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.
Chemo Brain: Memory and Concentration Problems: the quick overview
A one-breath explanation you can watch before an appointment.
Coming soonChemo Brain: Memory and Concentration Problems, explained simply
The core ideas with friendly animation and plain language.
Coming soonUnderstanding chemo brain: memory and concentration problems — 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: "Chemo Brain: Memory and Concentration Problems" with the Cancer Explained mark.
- 2Narrator reads the 30-second summary while a soft animated diagram builds on screen: "Some cancer treatments can make it harder to think, concentrate, or remember things. People sometimes call this mental fog or chemo brain. It can start during or after treatment, and it ranges from very small changes to much greater problems. Your doctor can assess your symptoms and suggest ways to manage or treat them."
- 3Scene 2: illustrate the idea — "Memory or concentration problems—sometimes described as a mental fog or chemo brain—can be a side effect of cancer treatment."
- 4Scene 3: illustrate the idea — "Chemotherapy, some types of radiation therapy to the brain, and immunotherapy may cause difficulty with thinking, concentrating, or remembering."
- 5Scene 4: illustrate the idea — "Whether these problems happen depends on the type of treatment you receive, your age, and other health-related factors."
- 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 "chemo brain" another name for?
Frequently asked questions
▸Is chemo brain a real side effect?
Yes. The National Cancer Institute describes memory or concentration problems—sometimes called a mental fog or chemo brain—as a side effect that can come with cancer treatment. Whether you have these problems depends on the type of treatment you receive, your age, and other health-related factors.
▸Which treatments can cause memory or concentration problems?
Cancer treatments such as chemotherapy may cause difficulty with thinking, concentrating, or remembering things. So can some types of radiation therapy to the brain and immunotherapy.
▸When do these problems start?
They may start during or after cancer treatment. Some people notice very small changes, such as a bit more difficulty remembering things, while others have much greater memory or concentration problems.
▸How long does chemo brain last?
The National Cancer Institute page this article is based on does not say how long these problems last. It suggests asking your health care team questions such as "When might these problems start to occur?" and "How long might they last?" Your team knows your treatment and can say more.
▸What can help with memory or concentration problems?
For minor problems, it can help to plan your day around when you feel best, get extra rest and plenty of sleep, exercise your body and mind, and use lists, planners, or other devices to remember important information. Treating conditions such as poor nutrition, anxiety, depression, fatigue, and insomnia may also help.
▸Should I tell my doctor about memory changes?
Yes. It's important for you or a family member to tell your health care team if you have difficulty remembering things, thinking, or concentrating. Your doctor will assess your symptoms and advise you about ways to manage or treat these problems.
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Questions to ask your healthcare team
Consider bringing these questions to your next appointment.
- Am I at increased risk of cognitive problems based on the treatment I am receiving?
- When might these problems start to occur? How long might they last?
- Are there steps I can take to decrease these problems?
- What symptoms or other problems should I, or a family member, call you about?
- Could I meet with a social worker to get ideas about additional support and resources?
- Are there specialists—such as a neuropsychologist or an occupational therapist—who could assess, treat, or advise me on these problems?
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