Chemobrain as a Side Effect of Chemotherapy

Why Can't I Think Clearly After Chemotherapy?

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Chemobrain is a relatively new term that refers to the cognitive changes that can occur as a side effect of chemotherapy. Many people who have gone through chemotherapy notice some temporary changes in their memory or thinking process (cognitive dysfunction.) It might be harder to do two things at the same time, the car keys disappear, and the event you just read about in the newspaper just doesn’t seem to stick in your memory.

It's thought that anywhere from 15 percent to 70 percent of people are significantly affected by chemobrain after chemo, but we are just beginning to learn about the causes, and what you can do to cope and recover from this annoying condition.

In addition, a study published in the Journal of the National Cancer Institute suggests that some of the symptoms we have been attributing to chemobrain are actually present before chemotherapy is given, at least for people with breast cancer, and may instead be related to post-traumatic stress symptoms or disorder in cancer patients.

Confused man with hand on chin reading adhesive note
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Symptoms of chemobrain have been described by some cancer survivors as “brain fog.” In his blog about his life with cancer the late Leroy Sievers shared his experience with chemobrain. He described these symptoms as: “It’s a little bit like the feeling you get when you’ve had one or two drinks too many, and you don’t want to be drunk. You will try to talk yourself into clarity but it doesn’t always work.” Symptoms of chemobrain may include:

  • Difficulty concentrating and thinking clearly
  • Trouble performing more than one task at a time (difficulty multitasking)
  • Decreases in memory – especially visual and verbal memory, such as problems remembering things that were said in a conversation, an item written on a grocery list, or the name of someone you recently met.
  • A shortened attention span
  • Becoming easily confused, especially when learning new information
  • Feeling disorganized


Side effects of cancer treatment, as well as the cancer itself, can contribute to many of the symptoms we describe as chemobrain. Anemia, sleep changes, depression, fatigue, and anxiety over a diagnosis of cancer can all affect your concentration. But chemotherapy may also play a direct role in these symptoms. Neuropsychological testing has shown that changes in the brain do occur during chemotherapy, and research is ongoing looking at the ways in which chemotherapy affects the brain. Imaging studies have found that early on, people may have a decrease in gray matter and a decrease in white matter volume in the brain, and for a subgroup of people, this persisted in the long-term. What this means is still uncertain. How much these symptoms are due to the rigors of cancer treatment, and how much is directly attributable to chemotherapy remains to be seen.

What is most important is that cancer survivors get the support they need to cope with symptoms they experience after chemotherapy.


Chemobrain can be very frustrating both for those who are living with cancer, and their loved ones who are trying to support them. Feeling disorganized can affect your quality of life and ability to make decisions. For those who are working or going to school, difficulties concentrating can be challenging on top of the fatigue most people already experience after treatment.


At this time, there isn't a specific treatment plan that has been adopted by oncologists. Some research has suggested that occupational therapy may be helpful. If you are coping with stress, relationship problems, or anxiety in addition to chemobrain symptoms, a consult with a psychologist or social worker may be helpful. This article discusses treatments and therapy for chemobrain.


The first step in coping with chemobrain is to understand that these symptoms are real and not “all in your head.” Give yourself permission to take extra time thinking through problems. For most people, symptoms of chemobrain improve significantly over time. Some tips that have helped others cope include:

  • Keep a calendar handy, and write down important dates and appointments.
  • Get enough sleep.
  • Exercise both your body and mind. Some people find that activities like sudoku or crossword puzzles help to challenge their minds and organize their thoughts. Even small amounts of physical activity can make a significant difference for some people.
  • Look at ways to manage stress in your life.
  • Avoid or minimize distractions.
  • Focus on a single task. Don’t try to do too many things at once. (Don't fret with this one - even for people without chemobrain, multitasking has been found to be ineffective.)
  • Eat a healthy diet. A diet rich in vegetables can give your brain a boost.

Day-to-Day/Relationship Concerns

If your symptoms are interfering with your day-to-day life at home, your oncologist may recommend that you see an occupational therapist. By examining you, the therapist may have advice on coping with your symptoms, and tools and possibly further therapy to make sure you can function safely at home. 

Considering some of the symptoms—forgetfulness and lack of concentration—it only stands to reason that your relationship with friends, your spouse, and children, may suffer. Since it isn't talked about as often as other side effects of chemotherapy—for example, nausea—and since the symptoms can be subtle, your loved ones may see your memory fog as not caring to listen to them or not caring enough to remember important dates, instead of a real symptoms related to your treatment. Talking openly with your loved ones, and educating them on the subjective and objective changes known as "cognitive dysfunction," may help to alleviate misunderstandings and hurt feelings—and in turn your support—down the line.

Employment Concerns

For some people, cognitive dysfunction can interfere with the ability to perform at work, and this can be incredibly stressful as you think of your career, not to speak of the financial ramifications if you are unable to work. If you find that you are unable to return to work, or if it's just not working when you return, it's important to know where to begin and understand your rights. The not-for-profit organization Cancer and Careers has a wealth of information to help you sort through the multitude of questions you will have. This site includes information on your legal rights in the workplace, when to talk, and when not to talk about our condition at work, and a major fear for many people in this situation; insurance questions about employment. 

When to Talk to Your Healthcare Provider

If you are experiencing any symptoms of chemobrain, talk with your oncologist. It is important that, as a first step, she talk to you and examine you for conditions other than chemobrain that may be causing or contributing to your symptoms. If your symptoms are interfering with your day-to-day life, she may recommend that you see an occupational therapist to see what tools/therapy you may need to function well at home. She may also suggest that you see a neuropsychologist. These psychologists can do a very thorough evaluation of your symptoms and recommend cognitive rehabilitation or cognitive remediation. The phrase cognitive remediation may sound scary, but it is simply therapy set up to help you find practical ways to cope with the areas that are distressing to you in day to day life until your symptoms improve in time.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."