Chemo brain is a common term used by cancer survivors to describe thinking and memory problems that can occur during and after cancer treatment. Chemo brain can also be called chemo fog, cancer-related cognitive impairment or cognitive dysfunction.

Though chemo brain is a widely used term, the causes of concentration and memory problems aren't well-understood. It's likely that there are multiple causes.

No matter the cause, chemo brain can be a frustrating and debilitating side effect of cancer and its treatment. Researchers are working to understand the memory changes that people with cancer experience.


Signs and symptoms of chemo brain may include the following:

  • Being unusually disorganized
  • Confusion
  • Difficulty concentrating
  • Difficulty finding the right word
  • Difficulty learning new skills
  • Difficulty multitasking
  • Feeling of mental fogginess
  • Short attention span
  • Short-term memory problems
  • Taking longer than usual to complete routine tasks
  • Trouble with verbal memory, such as remembering a conversation
  • Trouble with visual memory, such as recalling an image or list of words

When to see a doctor

If you experience troubling memory or thinking problems, make an appointment with your doctor. Keep a journal of your signs and symptoms so that your doctor can better understand how your memory problems are affecting your everyday life.


There are many possible factors that might contribute to the signs and symptoms of memory problems in cancer survivors.

Cancer-related causes could include:


  • A cancer diagnosis can be quite stressful and it might lead to anxiety and depression, which can contribute to thinking and memory problems
  • Certain cancers can produce chemicals that affect memory
  • Cancers that begin in the brain or spread to the brain might cause changes in thinking

Cancer treatments

  • Bone marrow transplant
  • Chemotherapy
  • Hormone therapy
  • Immunotherapy
  • Radiation therapy
  • Surgery
  • Targeted drug therapy

Complications of cancer treatment

  • Anemia
  • Fatigue
  • Infection
  • Menopause or other hormonal changes (caused by cancer treatment)
  • Sleep problems
  • Pain due to cancer treatments

Other causes

  • Inherited susceptibility to chemo brain
  • Medications for other cancer-related signs and symptoms, such as pain medications
  • Other medical conditions, such as diabetes, thyroid problems, depression, anxiety and nutritional deficiency

Risk factors

Factors that may increase the risk of memory problems in cancer survivors include:

  • Brain cancer
  • Cancer that spreads (metastasizes) to the brain
  • Higher doses of chemotherapy or radiation
  • Radiation therapy to the brain
  • Younger age at time of cancer diagnosis and treatment
  • Increasing age


The severity and duration of the symptoms sometimes described as chemo brain differ from person to person. Most cancer survivors will return to work, but some will find tasks take extra concentration or time. Others may be unable to return to work.

If you experience severe memory or concentration problems that make it difficult to do your job, tell your doctor. You may be referred to an occupational therapist or a neuropsychologist, who can help you adjust to your current job or identify your strengths so that you may find a new job.

In rare cases, people with memory and concentration problems are unable to work and may consider applying for disability benefits. Ask your health care team for a referral to an oncology social worker or a similar professional who can help you understand your options.

Feb. 09, 2023

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