Chemo Fog, Cancer Fog, Brain Fog ….. It’s real

You’re not going crazy

If you have had a cancer diagnosis and are having memory or concentration problems- you are not going crazy!

‘Cancer fog’, ‘brain fog’, ‘chemo brain’ or ‘cancer-related cognitive impairment’ are all terms used to describe memory problems caused by cancer. For simplicity I will refer to these terms collectively as cancer fog (CFog).

It has been over two years since my bowel cancer diagnosis, and I have only just discovered that cancer patients can develop CFog – without ever having received chemotherapy. Say whaaaat? How did I miss this important patient information? Well to begin with, no one has ever mentioned it to me during my recovery.

If you have read any of my past blogs you will know that I had an early bowel cancer. By the skin of my teeth I have managed to avoid the perils of chemotherapy. Every single day I count my blessings.

As it turns out, many people who are diagnosed with cancer experience CFog. In fact, a staggering 1 in 3 people experience the condition before and after treatment, and 3 in 4 people report CFog during treatment Cancer Council. This is huge! 

How it feels

People with CFog experience memory lapses and changes in the way that they think  My CFog felt like a grogginess, fatigue and not being as ‘sharp’ as I usually was.  If I’m entirely honest, it felt quite similar to the grueling sleep deprivation symptoms that newborns bring. It just lasted a lot longer and definitely wasn’t as fun!

I put my CFog changes down to being unwell, recovering from a big operation and sleep deprivation. All of which did contribute to my CFog- I just didn’t realise it at the time. My symptoms were more on the subtle side and started to resolve when I physically started to feel stronger. I had CFog for about 18 months.

I’m certain that my CFog started a few months before my diagnosis. I had recently returned to work after my second maternity leave. I was noticing that my concentration and even resilience had taken a blow. I was finding that I had to work harder to concentrate when writing important pieces of work, or even deciphering key messages from email chains. Arguably, these symptoms are also quite typical with baby/toddler associated sleep deprivation and the mum/work-life unbalance.

I’ve only discovered how common CFog is through my own research. I wish I had known a little more about what to expect and how to make my life easier during my recovery. Throughout my cancer journey I have always found that knowledge is power. There are so many ‘hints and tips’ that can make a cancer journey more manageable for patients and their loved ones. So here are some of the key pieces of information that I have come across in my research.

The beginning of memory changes

Memory changes can occur before, during or after cancer treatment. Some people will notice small changes in their memory and thinking, while other patients notice more obvious changes (Cancer Council). 

The symptoms: 

  • Memory lapses
  • Getting lost easily (even when going to familiar locations) 
  • Shorter attention span 
  • Concentration problems (“I can’t finish a book”) 
  • Difficulties with finding the right word 
  • Difficulties in learning new information or skills
  • Problems with planning and multitasking 
  • Slower thinking time
  • Tiredness and fatigue 
  • Unable to keep up with conversations (“I now find dinner parties stressful”)
  • Difficulties with solving problems 

Why do people experience CFog? 

While the exact causes of memory changes in cancer are not entirely understood, the research to date has shown that the following can contribute to memory changes:

  • cancer treatment
  • treatment side effects – pain, low blood counts, hormone changes, sleep deprivation 
  • medications – anesthetics, pain relief, steroids and anti-nausea drugs
  • stress and anxiety
  • a tumor in the brain if the patient has brain cancer

Cancer Council & Evens & Eschiti (2009)

How long will it last? 

Symptoms can last months to years. 

What patients say

Patients with CFog often report general forgetfulness, being easily distracted, and problems with getting lost. It can be stressful and sometimes scary. People wonder ‘will I ever be the same again’? CFog can also impact on a person’s daily activities, relationships and in some cases their ability to return to their job. Some people experience a loss of their independence and need help with paying their bills or managing other financial affairs.

We’re not talking minor inconveniences here- we’re talking significant changes to capability. Albeit usually these symptoms are short-term. 

What patients have shared with me

“I thought I’d lost my baby and was looking for her… my 8yo had to inform me I was holding her…
My oncologist loved that one.”

“I didn’t receive any information about chemo fog throughout my treatment”.

“I have quite a mentally demanding job & there was big parts of my role I couldn’t do – I had a very understanding manager & we adapted my role while I was on treatment. There were some tasks that I could literally not do.”

“I used to be a great multi-tasker, but now… wait what was I saying?”

“I can literally only manage 1 thing in my brain at any 1 time. I am forgetting birthdays, coffee dates and appointments. I rely heavily on my phone calendar these days.”

“The only cancer fog information I got was in a few written resources. It was only when I read a book about chemotherapy that I understood why I was experiencing my symptoms”.

“I feel like my vocabulary has taken a big hit. I’m forever searching for an elusive word! It’s so frustrating.”

“I used to go into rooms and forget why I went there and what I was going to get… or turning the wrong way down a street that I was very familiar with…”

“Gosh.. it really is a fog and until the fog has lifted, you don’t realise how bad it really was. You really are in a daze 24/7, living in a semi-reality. Some of my chemo time I can scarcely remember or it feels like it was in a dream.”

“It’s constantly being concerned you’re forgetting something (because you are).”

“I’m about 9 months post chemo, and even now I can have a 15 min reminder pop up for a Zoom mtg for work in my calendar, and I’ll forget about it within 5 mins. (I’ve had to change all my reminders to 5 mins before so I can log on straight away).”

“I wish my doctor would have explained cancer fog to me, it was my most debilitating symptom.”

“Every so often I look back and think, I’m doing so much better than I was 6 months ago. It’s always funny because each time I thought I was doing sooo much better than during chemo, and I was, but I didn’t realise exactly how far from my ‘normal’ I had shifted. Memory, processing speed, creativity, comprehension, making connections – all of it was like trying to wade through concrete mentally. After 2 years I think I’m pretty close to that ‘normal’ for the most part, but some days are a real mental struggle sometimes, especially as the rest of life and responsibility gets levelled up again.”

“I couldn’t concentrate on a conversation with more than 2 people. I’d forget names, appointments etc & constantly repeat myself (well according to my Mum).”

“My mental capacity has gradually improved as the time has gone, however it took me 12 months to gradually build up from 12hrs/fortnight to a full 38 hr work week due to both mental and physical fatigue.”

“Rosters…OMG..I made so many mistakes on the staff rosters…the staff complained to MY boss…he told them to cut me some slack….worked from home 4 hours per day for 6 months, then gradually went back to about 30 per week.”

(All feedback shared generously with permission)

What health professionals should consider 

Quality of life is important to cancer patients- really important.  Which means we want to know about potential side effects from our cancer/treatment, how to reduce and manage the side effects, and how long they are going to last. 

Some patients find that certain (non-life threatening) side-effects including CFog can be ‘glossed over’ during medical appointments.  For others, the first that they hear about CFog is when they google their symptoms, ask about memory changes in an on-line forum, or raise their new memory changes in a follow-up medical appointment.

Some researchers point out that CFog increases when patients were forewarned about the potential of developing CFog. So if patients think that they are going to get it- they are more likely to get it! My ten cents- I would say that informing patient of potential risks outweighs the potential for a nocebo effect. But- It is HOW you educate the patient’s that is important. Tell them about the risk- but emphasise it is usually short term and focus on the strategies to reduce and and manage CFog. Giving patients early information and quality resources is key to acceptance and management. 


  • Talk to your medical team about your symptoms 
  • Be kind to yourself and try not to be self-critical when you can’t remember 
  • Use a daily planner, ‘to do lists’, notes, maps and reminder alarms
  • Keep to a daily routine 
  • Use a diary to record what makes your memory better or worse 
  • Do more mentally intensive activities in the morning or when you feel more rested
  • Acceptance will allow you to find solutions faster
  • Focus on single tasks at a time and avoid distractions  
  • Relax and reduce stress – yoga, mediations, listening to music
  • Optimise your sleep- aim for 7 to 8 hours each night 
  • Rest when you need to 
  • Let your friends and family know. People are usually more understanding once they know  
  • Exercise regularly
  • Good nutrition – including antioxidant fruit, vegetables, high quality protein, vitamin B and vitamin D 
  • Some patients have reported improvements with acupuncture
  • Talk to your GP about a referral to an allied health professional such as an Occupational Therapist or Clinical Psychologist. In Australia you may be able to access these services through your hospital, or be eligible for Medicare rebates for community appointments.  
  • The Cancer Council also has some fantastic information on Cognitive Rehabilitation

Support and Surrender 

CFog is real, requires further research and needs to be discussed more with patients. Forewarned is forearmed. CFog symptoms vary, are often subjective (difficult to test for) and can be mild to significant. There is support out there for you. Rest, strategies, expert guidance and above all- patience with yourself is key. Remember- your body has had huge demands imposed on it, often received countless medications, and you have been on an emotional rollercoaster. Honor yourself by giving yourself the time and permission to recover. 

Thank-you to my Cancer Community

A huge thank-you to the many beautiful members of my cancer communities who generously share their personal experiences and feedback with me. Sharing our stories collectively is so important to help pave a slightly easier road for those patients whose journey is just beginning. I am forever grateful xxxxxxxx

Resources and References

** I highly recommend this Podcast- Brain Fog and Cancer****

Boykoff N, Moieni M, Subramanian SK. Confronting chemobrain: an in-depth look at survivors’ reports of impact on work, social networks, and health care response. J Cancer Surviv. 2009;3(4):223-232. doi:10.1007/s11764-009-0098-x

Cancer Council Australia – Understanding Changes in Thinking and Memory

Evens K, Eschiti VS. Cognitive Effects of Cancer Treatment: “Chemo Brain” Explained. Clinical Journal of Oncology Nursing. 2009;13(6):661-666. doi:10.1188/09.CJON.661-666

Hislop JO. Yes, Virginia, Chemo Brain is Real. Clinical Breast Cancer. 2015 Apr;15(2):87-89. DOI: 10.1016/j.clbc.2014.09.004.

Kovalchuk A, Kolb B. Chemo brain: From discerning mechanisms to lifting the brain fog-An aging connection. Cell Cycle. 2017;16(14):1345-1349. doi:10.1080/15384101.2017.1334022

Physical Fitness Helps Overcome “Chemo Brain” in Cancer Patients and Survivors: Being physically active helps combat fatigue and cognitive impairment. DukeMedicine HealthNews. 2017;23(11):6. Accessed March 25, 2021. direct=true&AuthType=ip,athens&db=mdc&AN=EPTOC126049759&site=eds-live

Schagen SB, Wefel JS. Chemotherapy-related changes in cognitive functioning. EJC Suppl. 2013;11(2):225-232. doi:10.1016/j.ejcsup.2013.07.007

We hope that you enjoyed this article. Please drop us a comment below, we would love to hear from you.  

X The Awakened Mumma, Author of ‘A Woman’s Guide to Navigating the Invisible Cancer Load

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