What Is “Chemo Brain” + How Long Does It Last?

Brain fog during chemo is common, frustrating, and very real.

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Chemotherapy comes with many side effects that are often visible and hard to deny, such as hair loss and nausea. However, one side effect that is often unfairly brushed aside is “chemo brain,” or cognitive changes during chemotherapy and other treatments for cancer.

Chemo brain is real—and incredibly common in people undergoing chemotherapy. Most people who experience chemo brain describe it as causing things like memory lapses, slower processing, difficulty multitasking and concentrating, and forgetting common words.

Chemo brain can also lead to emotional symptoms. The mental cloudiness can be very frustrating, and it can add stress to an already stressful period of someone’s life.

What Causes Chemo Brain?

There’s no single answer for this question, and in fact, some people experience “chemo” brain fog without even undergoing chemotherapy. Thus, doctors believe chemo brain is actually the result of a complex mix of factors, such as:

  • The cancer itself, such as a tumor in the brain

  • Anti-nausea meds and other related drugs to relieve side effects

  • Anesthetics used during surgeries

  • Low blood counts

  • Lack of sleep and general fatigue

  • Hormone changes

  • Nutritional deficiencies, which are common due to lack of appetite and nausea

  • The age of the patient

  • Depression, which is common among people undergoing cancer treatment

  • And stress.

How Long Chemo Brain Lasts

The majority of chemo brain symptoms come and go quickly. When chemotherapy or other cancer treatments stop, most people see their chemo brain (and other chemo side effects) fade away.

However, some people do experience long-term cognitive changes. Some risk factors, such as depression, are linked to a higher chance of long-term cognitive side effects, according to the American Cancer Society.

Coping with Chemo Brain

Chemo brain isn’t simply frustrating: It can actually get in the way of treatment. It could cause patients to forget doctor’s instructions about medications, or to forget to ask certain questions during appointments, for example.

While chemo brain isn’t your fault, prioritizing a healthy lifestyle during treatment can help mitigate some of the symptoms of chemo brain. That includes eating a balanced diet with lots of veggies, getting enough sleep, exercising, and managing stress.

Additionally, it can help to stay organized during treatment. Keep a symptom diary to show your doctor during appointments, as well as a detailed planner to keep track of appointments and other important events. Write down your questions before heading to appointments, and bring a loved one to help you remember instructions and other details. Take notes during appointments, and keep a list of all your medications.

Perhaps most importantly, tell your treatment team and your loved ones that you are experiencing brain fog from your cancer treatment. This can help increase support so you feel less guilt or pressure regarding your cognitive symptoms.

“In patients that are worried about it, I let them know that it’s not something that’s guaranteed to happen, and it may not happen at all,” says Ashish Saxena, MD, oncologist at Weill Cornell Medicine and NewYork-Presbyterian. “Like a lot of other side effects, [chemo brain] will get better [after] time away from chemotherapy.”