Skip to main content

What is chemo brain and how long does it last?

Medically reviewed by Kristianne Hannemann, PharmD. Last updated on May 27, 2025.

Official Answer by Drugs.com

Chemo brain, also known as chemotherapy-induced cognitive impairment (CICI), chemo fog, or cancer-related cognitive impairment, refers to the cognitive difficulties experienced by many cancer patients during and after chemotherapy treatment. This condition is characterized by a noticeable decline in mental abilities, including memory, learning, attention, and executive functions such as planning and multitasking. In this article, we will take a closer look at what chemo brain is and how long it typically lasts.

What Is Chemo Brain?

Chemo brain refers to memory and thinking problems linked to chemotherapy. It can occur before, during, and after cancer treatment. Other causes of cognitive problems besides chemotherapy include tumors present in the brain and treatments such as hormone therapy, radiation, and surgery. It is estimated that up to 34% of patients receiving chemotherapy report cognitive problems.

One of the main mechanisms behind chemo brain from chemotherapy medications is believed to be neurotoxicity. Certain chemotherapy medications have been linked to oxidative stress and mitochondrial dysfunction, resulting in DNA damage in brain cells. Other potential causes include inflammation in the brain and disruptions in the blood-brain barrier.

What Are the Common Symptoms of Chemo Brain?

The symptoms of chemo brain can vary among individuals, but commonly include:

These symptoms can significantly affect daily functioning, work performance, and quality of life for cancer patients.

How Long Does Chemo Brain Last?

The duration of chemo brain is highly variable. For some, cognitive symptoms are most pronounced during or immediately after chemotherapy and improve within months. However, studies indicate that for others, these effects can persist for years after treatment ends. In one study of 581 patients with breast cancer, some patients still reported cognitive impairment 6 months after stopping chemotherapy.

The prevalence of cognitive impairment after chemotherapy has been estimated to range from 15% to 75%, depending on the type of cancer, treatment regimen, and assessment methods used. Persistent symptoms are more likely in those who received higher doses or longer courses of chemotherapy, or who had additional risk factors such as older age or pre-existing cognitive problems.

Does Chemo Brain Ever Go Away Completely?

For many patients, chemo brain symptoms gradually improve over time, especially within the first year after treatment. However, some survivors report ongoing cognitive difficulties that can last for several years or even become permanent. Complete resolution of symptoms is possible, but not guaranteed for everyone.

The degree of recovery often depends on individual factors, including overall health, age, type of chemotherapy, and the presence of other medical or psychological conditions. Research on potential treatments for chemo brain is ongoing.

How Can You Manage Chemo Brain?

While there is currently no definitive cure for chemo brain, several strategies can help manage and reduce its impact:

Discuss ways to improve and cope with your cognitive symptoms with your oncologist or primary care physician. They can rule out other potential causes and refer you to specialists if needed.

Conclusion

Chemo brain is a well-recognized side effect of chemotherapy, affecting a significant proportion of cancer patients with symptoms that can range from mild to severe. While many experience gradual improvement, some may face long-term cognitive challenges. Proactive management—including lifestyle changes, cognitive rehabilitation, and support from healthcare professionals and patient support groups—can help mitigate the impact of chemo brain and improve quality of life for survivors. Talk to your healthcare provider if you notice signs of chemo brain so they can help you determine the cause and offer tips on managing your symptoms.

References
  1. Cancer Research UK. 2023. Research looking at cognitive changes (chemo brain). Accessed on May 27, 2025 at https://www.cancerresearchuk.org/about-cancer/treatment/cancer-drugs/side-effects/chemo-brain/research
  2. Janelsins, M. C., et. al. 2016. Cognitive Complaints in Survivors of Breast Cancer After Chemotherapy Compared With Age-Matched Controls: An Analysis From a Nationwide, Multicenter, Prospective Longitudinal Study. In: Journal of Clinical Oncology. DOI: https://doi.org/10.1200/JCO.2016.68.5826
  3. Miyashita M. 2023. Chemotherapy-related cognitive impairment: What we need to know and what we can do. Asia-Pacific journal of oncology nursing, 11(1), 100334. https://doi.org/10.1016/j.apjon.2023.100334
  4. Murillo, L. C., et. al. 2023. An update on neurobiological mechanisms involved in the development of chemotherapy-induced cognitive impairment (CICI). Toxicology reports, 10, 544–553. https://doi.org/10.1016/j.toxrep.2023.04.015
  5. National Cancer Institute. NCI Dictionary of Cancer Terms: chemo brain. Accessed on May 27, 2025 at https://www.cancer.gov/publications/dictionaries/cancer-terms/def/chemo-brain
  6. The University of Texas MD Anderson Cancer Center. Chemobrain. Accessed on May 27, 2025 at https://www.mdanderson.org/patients-family/diagnosis-treatment/emotional-physical-effects/chemobrain.html
  7. Umfress, A., et. al. 2021. Neuropathological Effects of Chemotherapeutic Drugs. ACS chemical neuroscience, 12(16), 3038–3048. https://doi.org/10.1021/acschemneuro.1c00338

See also: