Personality Changes in Cancer Patients

chemo personality changes

How can cancer impact someone’s personality?

There isn’t a “right” way to deal with cancer. Sadness, anger, hope, numbness, fear, determination, denial: the list of feelings you might experience along the journey is endless, and you have every right to feel them. However, if you notice a very sudden change in your own behaviour, or someone you care for seems very different since their diagnosis or treatment, there might be something else going on too.

Here are some of the things you might notice.  

  • Depression and “flat” emotions
  • Anxiety
  • Mood swings
  • Irritability or aggression
  • Apathy (lack of interest and motivation)
  • Confusion and forgetfulness
  • Lack of inhibitions – behaving in socially or culturally unacceptable ways
  • Difficulty planning and organising
  • Difficulty concentrating
  • Difficulty identifying emotions in yourself and others

Of course, every person is different – and everyone will react differently to the difficult experiences cancer brings. For some people, any “personality changes” might just be a totally normal reaction to a life-changing event, but there are other factors that could be affecting someone’s behaviour.

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Why might personality changes happen in cancer?

cancer survivor personality changes

Mental health

Nobody is going to feel okay when they’re told they have cancer. Feeling extreme emotions after hearing bad news or when going through illness and treatment is completely understandable, and it’s important to feel these emotions instead of trying to hide them. But if they’re getting in the way of your day-to-day life, your recovery, or enjoying time with your friends and family, you don’t have to “just get on with it” – there are lots of ways to get help and feel a little bit better.

Worry and anxiety

Stress and anxiety aren’t just in your mind. They can have real, physical effects on your body too. When you’re very anxious you might find that you have trouble sleeping, or you may feel sweaty or nauseous. Some people might even experience panic attacks or shortness of breath. These feelings might be more intense in the run up to appointments or when waiting for results, or they may come and go at seemingly random times.


Feeling sad and low when you have cancer is a normal response to a horrible situation. But feeling continuously low or unable to function for more than a couple of weeks, or having thoughts of harming yourself, could be a sign that you’re experiencing depression.

Mental health problems are really, really common, and they are even more common amongst people coping with long term illnesses such as cancer. The most important thing to remember is that mental health problems can be easily treated – even if you have cancer. You don’t have to suffer from anxiety, depression or other mental health issues on top of your illness. And getting the right help and support for your mental health could help you feel more equipped to face the other aspects of cancer.

What can I do?

Talking to your doctor about emotional issues as well as physical ones will give them a better overview of how things are going. They may be able to prescribe you medications that will help with anxiety and depression, and they may also refer you for counselling or therapy if you feel it would be helpful to talk. You might also find it helpful to think about some techniques proven to help with managing anxiety and depression, such as mindfulness, CBT or gentle exercise.

Chemo brain and personality changes


chemo rage picture - woman experiencing chemo anger

We hear so often from our community about their struggles with chemo brain. The feeling of “mental fog”, difficulty concentrating or remembering things, and other cognitive issues can really impact someone’s life, and are a common personality change after chemo. However, another phenomenon we sometimes hear about is “chemo rage”.

Chemo rage

Anger is a completely reasonable response to cancer and the many difficulties it brings. But for some people, their cancer treatment is accompanied by a sudden, uncharacteristic increase in irritability, angry outbursts, and even aggressive behaviour. This can be really alarming and upsetting for both the person going through cancer and their loved ones.

What’s going on?

Though this behaviour might be a purely emotional reaction, there is also the possibility that it may be influenced by medications and treatment. Often, cancer treatments are accompanied by steroids, to make the therapy more efficient and to manage some side effects. Unfortunately, a potential side effect of steroids themselves is an increase in mood swings, and particularly in irritability and anger – sometimes called “roid rage”.

If you recognise this behaviour in yourself, or suspect that someone you care for is having this reaction to steroids, the answer is (as always!) to talk to your doctor. Please don’t stop taking any medications or change your dosage – your doctor will be able to advise you, talk through your options and potentially prescribe something to counteract this side effect.

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Hormones and the endocrine system

hormones and personality changes in cancer patients

Personality changes in cancer may also be due to impacts on the body’s hormones. Hormones are chemicals released by your body that help to keep it functioning. They control our metabolism (how we produce and use energy), how we respond to changes in our environment, our sexual functioning and our mood.

So if cancer or its treatment interferes with the hormonal system, this can have a huge effect on your body and how you feel, both physically and mentally.

For example, low testosterone levels have been linked to increased irritability in men – we’ve heard it described as “what makes grumpy old men grumpy”. Likewise, we know that reproductive hormones can have effects on mood, appetite and metabolism, in both men and women.

As well as causing problems in your body’s own hormonal systems, some cancers can also release their own hormones into the bloodstream, causing their own side effects. It’s worth talking to your doctor about hormones and how they might be affecting your or your loved one’s mood, behaviour and personality.

Changes in your brain

personality changes after chemo - chemotherapy-induced brain changes picture

Your brain is the computer that runs your whole body. It’s constantly sending and receiving information to and from every part of you, controlling all the systems that keep you going. It also processes all your memories, thoughts, feelings and behaviour. So if your brain is affected by cancer or its treatment, it’s likely that you will experience some changes in personality. These may be temporary or more long term, and can be very scary to deal with.

Brain changes can come about as a result of a brain tumour, or due to brain swelling following treatments such as chemotherapy. The experience many patients describe as “chemo brain”  is also an example of cognitive (thinking) and emotional changes due to alterations in the brain’s structure and chemistry.

Similar personality changes may also happen if a person’s liver is failing. If the liver isn’t able to remove all the harmful chemicals in the blood, these “toxins” can build up and enter the brain. This is called hepatic encephalopathy (HE), and can come about suddenly if the liver shuts down, or more slowly as a result of long term liver damage. HE is a treatable condition, so it’s important to recognise the signs and get medical advice as soon as possible.

What can I do?

If you or someone you care for is experiencing personality changes, there is a lot that can be done to try and manage the condition. Your doctor may be able to prescribe steroids to reduce brain swelling. Medications or therapy for anxiety, irritability and depression can also help things to feel more normal again.

Caring for someone with personality changes

caring for someone with cancer personality changes

Experiencing personality changes with chemo or cancer may be scary and upsetting, not only for the person going through cancer but also for their loved ones and carers. You might find that you experience more conflict in your relationships, or it might be hard for you to communicate as easily as you did before.

At times like this, it’s important to get all the support you can, from friends, family, support groups or even the online community. Talking to other people who understand will help you feel less alone, and can remind you of all the good things about the person you’re caring for, even when times are really tough.

Though personality changes in cancer may happen for many reasons, from mental health to chemical changes in the body, it doesn’t really change what you or friends, family or carers have to cope with. Seeing someone act differently to the person you know and love can be very distressing, and of course being that person can be scary too.

What can I do?

mindfulness for cancer personality changes picture

When we were researching this article, one tip we found in the online cancer community really stuck with us. It was posted as a response to a lady struggling to communicate with her father after his cancer treatment.

“My only suggestion is to write him a letter, telling him how much you love him, and maybe recalling some happy things you have done together. You don’t have to make it gloomy, just put down your feelings. Then he can read it when he feels like it, and perhaps respond when he feels like it. Sometimes our clams who find it hard to talk about their feelings can be more easily reached at one remove.”


We thought this was a wonderful suggestion for anyone finding it difficult to deal with changes in a loved one’s personality. We’d love to hear any ideas you have for coping with personality changes and cancer, too. You can share them with us and our whole community on our Facebook or Twitter pages, or by emailing us at

Whether the personality changes you’re experiencing are a medical issue or simply a completely understandable reaction to a life-changing event, the best and most important thing you can do is to talk to someone about them. Getting advice from your doctor on possible treatments, medications, and therapy is the first step, and there are many other sources of support out there too.

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31 Replies to “Personality Changes in Cancer Patients”

  1. Thank you for this article! I am going through some very difficult times with my husband (Cancer treatment since 2014). His anger is affecting our whole family and now is spilling out to our friends. However, he won’t even consider talking to his doctor or a therapist. I’m printing this for my husband and son. I hope my husband will read it and understand that I want to help. Thanks again.

    1. Hi Claudia, so sorry to hear you and your family are going through tough times. Glad you found the article helpful – all the very best to you and your husband.

    2. i am going through this too with my husband,i don’t even know who he is anymore, he treats me like dirt, says horrible things and calls me pure evil names, he refuses any help, he won’t talk to me, he is very unpredictable and rips my heart out everyday, i cry day and night, so much pain, sorrow, heart break, feeling helpless, he has shut me out completely now. can not do anything right, stay away from him as much as possible because i fear me.

  2. My husband, who has always been very healthy, a weight lifter, runner, skiier, body builder and vegetarian was recently diagnosed with cancer. We have been together over half our lives and he is still very young (40s). His anger and mood swings and rage against me are almost just as bad as watching him suffer from his diagnosis. His treatment at this point has not been too painful. This article helped me a lot as he recently decided he wants a divorce and I feel like I do not know him at all anymore. This article makes me very sad, but it helps me tremendously to know that perhaps it’s not just because of me he’s so hateful, but perhaps indeed because of the cancer and the steroids, as well as the chemo. Thank you!

  3. Someone I know has recently come off chemo and radiation and is in remission. Thankfully they beat the disease, however, their personality and the way they act towards people now is not very pleasant, in fact its rude and insulting and pushy. Its as if we don’t know this person anymore. Could their sudden change in personality be affected by coming off treatments?

    1. Hi I have the same situation with the husband’s cousin. The cousin tends to explode at my husband but not other cousins or friends. If the mood swings really caused by medication or news, then why is only certain people are being explode at?

  4. None of this helps to know at all. He is nasty and regularly “nukes” me. I am so angry with him. We have been married for 39 years and I don’t care about the why. In fact, he has always chosen this way to vent his anger, it has just gotten so much worse and now I am unable to give him a pass on it. If it doesn’t change, just to protect myself, I will have to withdraw from him. I want to set limits on his behavior. Tell him if he wants me to stick around he will need to check his cruelty and meanness at the door. Every time I try to talk to him he just ramps up the poor behavior and I quite simply can no longer deal it. How about addressing these kinds of guilt-producing feelings? I am starting to feel less and less guilty the longer he takes it out on me. I am just, plain furious. And what about the fact that it is just as hard for me as it is for him? Just because my experience is on the other side of this does not mean I am not going through as much as he is. I have a right to expect to be treated with respect.

    1. Hi Nancy, I too am feeling totally frustrated with the way that my husband is acting towards both me and our children. He has always been quite demanding but now makes little effort to do simple tasks and expects us to drop everything at his command. He is however, the perfect patient in hospital and the nurses seem to think so too, even though he refuses to eat the hospital meals and will simply not eat if I don’t bring in food from home for him. He knows how to play on my guilt and has become an expert in that field. I want to be his loving wife of 25 years but the mind games that he is playing are taking their toll. I am sorry that he is sick but I’m not sick and yet my world has been turned upside down too. I didn’t sign up to be a carer!

    2. After much reading and going through this myself with my S.O., I understand the irritability is normal. Please realize this is not about something you did or didn’t do. They, I’m not sure are in control of themselves. I simply am stepping back, saying little, but loving him from a distance realizing this is not the person I fell in love with but a temporary complication of the illness and treatment. I just wish as a caregiver I was educated on all of this, it would have been somewhat easier to understand. PEACE.

    3. Amen. My wife is cruel now. I know that God is in charge. And that is my only hope. That He knows her and He knows me. He will not call me to do such hard things as forgive and live upright in her world unless He provided the way and strength to do it. I am not strong, I just trust God.

  5. My husband has a high grade cancer diagnosis and is retired military who does not allow illness. He will not even say the word “cancer”. He had surgery and one round of chemo in a nightmare stuffed recliner warehouse with no consideration for respect, privacy or dignity. Does not allow family to know. Oncologist not into communication. At the end of 1st round he fired him. He was done. He is adamant he will not do this again. Our Doctor spent 4 minutes at an appointment with his hand on the doorknob to exit. Annoyed if you asked him any questions. I am a mile passed angry. Patients deserve better. How can an office state “care and communication” in brochures and not do that? The cost just went over $140,00 with his surgery and chemo. Is the cancer industry all just money because it seems that way. Obviously talking to a counselor is out of the question. So is a second opinion because he will not cooperate. At this point I have no options. Has any one else encountered this environment?

    1. Hi there,

      I’m so sorry to hear what you’ve been going through. One cancer diagnosis can touch so many people around the person affected, and the struggles of family and loved ones are too often overlooked. You mentioned that your husband doesn’t want to talk about it with the wider family, and that must feel like a very heavy burden for you to manage on your own. In fact it sounds like communication in general has been very difficult between doctors, oncologists and you and your husband. It’s so frustrating to hear that the people you need answers from aren’t offering you comfort or solutions – you’re right, patients do deserve better.

      As I’ve never been in your position myself, I hesitate to give any advice or suggestions – but if you’re still feeling frustrated, alone or needing to talk to people who do have experience of something similar, I’d really recommend our Facebook support group. It’s totally free, and we have over 1300 members from all over the US and UK who are going through cancer or supporting people with cancer. People are generally very open to reading other people’s stories, offering helpful advice or just a listening ear, and a lot of our members have told us they find it easier to talk to people online than with family or people too ‘close’ to their own situation. You can join the group here:

      Of course, if that’s not your cup of tea I totally understand – and I really hope you manage to get some respite from the stress of trying to help your husband through the cancer industry nightmare you’ve been going through. I hope despite finding it difficult to talk about cancer, your husband finds a care path that feels more comfortable. Wishing you both the very best.

      Take care,
      Emily at Live Better With

  6. My anger has very little to do with the “Treatments for Cancer”….but more the way I was treated by the Best in the World Cancer hospitals in Boston.. all Harvard Doctors.

    False positives all over the place from lab results to cat scans, ultrasounds. False positives on DNA results. Late results. Mixed messages everywhere. Me having to push and insist on earlier schedules for surgery and radiation..knowing the sooner the better. All of this resulted in me thinking that I was knocking on death’s door..and then it was woops.. sorry that was a false positive.

    I did get professional great surgery and radiation treatment. They were good technicians. However, I would suggest anyone stay away from Residents (you do not have to deal with them if you do not want).

    I made some very poor decisions while thinking I had very little time left that ..oh if I only have a year to live..I will just quit my job.
    Am I angry.. yes. My advice do not ever put yourself in a position of being a dependent patient.

  7. Research studies indicate that mindfulness can be a powerful tool to help decrease anxiety and stress. Most people who learn how to practice mindfulness become less anxious, more stimulated and experience less symptoms of stress. Mindfulness helps enhance a person’s ability to focus, and end up being more engaged in their task.

    1. Being mindfulness…..that is interesting, and it has crossed my mind about my husband. When he first started taking the Chemo (Carboplatin and Alimta) and Keyturda, this past May, in two days after treatments his anger was horrible, his face showed it alone, he would just get into his truck and squeal out, scary to say the least, after 2 or 3 treatment times it became worse, so I called the oncology office and asked if this was normal for those on chemo, they of course said “no, we never heard of it”. But I knew it had to be that, so after a week of extreme anger after each treatment, I told my husband of his out bursts and that I called the doctor about it, he then did end up realizing he was getting out of control…so I am guessing that was his (my husband) first step to “mindfulness”. Although he is better than the beginning which of his 1st few treatments, he still is terribly moody, but I too am gaining more “mindfulness” and I stay away and I do not talk to him much as it seems to agitate him, unless I just ask simple questions like “would you like a sandwich”…

  8. I wish I would have found this article earlier this year. My wife was diagnosed with breast cancer a year ago. Chemo was first and she was kicking ass up until about the 4th , out of 8, infusion treatment. I started noticing rage that was getting more directed at me. As the caregiver you accept that your S.O. is going through a real bad time and you will continue to do what needs to be done. Now all of that rage is directed at me and I’m losing my mind. I love this woman but you can only take so much.
    If anyone reads this that has a loved one starting chemo, my one piece of advice would be to seek a support group. I wish I would have myself.

  9. My wife of 20 years is undergoing low dose chemo and radiation for stage 3b cervical cancer. I am finding it more difficult to go through this with her each day. Nothing i do is good enough. She finds fault in all that i do. She refuses to leave the hospital but declines a nursing home, counseling, or pallitive care. She even refuses physical therapy and at times to take meds by mouth. I have been talking with her doctor and social services as well as our grown children. Over the past 2 days i have seen divorce lawyers. We have a young child still in the home with us whom on a fortunate note has been and is bonded to me as the primary parent. I love my wife but have also had time to see that i have also been the victim of domestic violence long before cancer entered our lives. The last thing i want to do is give up on our marriage and run but i am at my wits end. I really want to blame all these problems on the cancer treatment but after much research i have found that the meds only add to what was there all along. Tomorrow morning i am going to ask her to please attend family counseling. The will be no ultimatum given or any mention of divorce. This is the hardest thing to do. I pray god will give this family what it needs and hope that gods will will set upon my wife with the holy spirit to accept the plea for family counseling.

    There should have been some type of precouseling prior to treatments about how relationships can be affected. Even my older children avoid seeing her at this point. I ask and hope that someone sees this and has a prayer strong enough to reach god to move upon this family before i give out and begin the divorce process.

  10. I have been felt crazy since my cancer treatment. It’s probably been worse since I had a failed mastectomy, I thought I was okay and the next day whisked into surgery to have my reconstructed breast sliced off. I couldn’t bear to look at my body for a month, showering eyes up. I am in my early 40’s. I was, in my eyes and others, a wonderful, Christian wife and awesome mom of 3 kids. Now my teenager hates me, and my mother actually accused me of being on speed! My best friend just told me she has bawled because she feels as if she has experienced the ‘death’ of her best friend. This sucks for us too! I try to curb my tongue but it’s like the switch that kept me from being rude, or saying hurtful things, from cussing like a sailor is broken. Things fly out of my mouth that I never ever would have said. There are lines you don’t cross and although my brain knows this, my mouth doesn’t. If you ever had too much to drink and spoke a little too loosely, then woke up the next morning groaning because you can’t believe you said THAT; well, that’s how I feel all the time without any drinking. Then there is the rage. I used to get mad, now I truly get enraged. I am scared to death of losing the love of my family and friends. I am about to have an anxiety attack just writing this but I have never heard of this happening. Why don’t doctors warn you? Why don’t they talk to your family? Encourage you to see a therapist from the start? I do not understand. I was starting to believe absolutely that I must be bipolar… Everything is different and confusing and hard and I am so sorry to everyone I have hurt or will hurt in the future. I just do not know what to do and it’s breaking my heart. My four year old son may never know the mother that I once was. If I can’t be me, do I want to live?

  11. The love of my life (28 years) together was diagnosed with Colom cancer in 2016, had op followed by 6 months of chemo. He is (was ) always volatile but after chemo it become hell on earth. The rage, hatred, verbal abuse mood swings etc etc, got to the point where we are no longer a couple,. His choice, blaming everything n everybody for issues. I’ve never seen so much hatred being direct at those that love him.Cancer is a horrible disease, but the poisons in the chemo is far worst. Chemo cost me my relationship

  12. Hi everyone, thank you for reaching out with your stories on this post – it sounds like many of you have struggled with the emotional side of cancer treatment, I’m really sorry to hear that it’s affected your relationships so deeply.

    Just to let you know, if you feel like you need a chat or some support on this topic, or anything to do with living with cancer, we’ve just launched a forum where you can have those conversations – it’s totally free, you can stay anonymous, and takes less than a minute to join.
    It’s a lot easier to have a proper chat in there than in the comments section here, and our members are other people going through cancer or helping a loved one.

    I’m also moderating the forum, so if you have any questions about how it works, you can drop me a message on there and I’ll help you figure it out.

  13. This is so little talked about. I think outsiders see a cancer diagnosis as something that brings a family closer together, but living with someone who experiences extreme anger at their diagnosis is so difficult. I didn’t want to talk about how awful it was, because I didn’t want to be seen to be detracting from husband’s suffering. It took even my closest friends a long while to realise. We need to talk about this more. We need to let carers know that this is not unusual, and that it’s ok to seek help.
    I suffered emotionally and physically at the hands of my husband, and while I tried to rationalise it by blaming the illness and the drugs, my children were suffering. They saw the rage, they were it’s target at times. I could do nothing right….
    It got to the point that the only way I could protect my mental health and the children was to leave. If only I’d had the support to hang in there for the final few months.
    At least I was the one there holding his hand at the end.

  14. My wife decided to divorce me after a year she completed her cancer treatment, she slowly changed into a different person, she kept quiet about her feelings, and emotions until one day she decided to be free, to find peace and left.
    I look at pictures of her and she even looks different before and after cancer, sometimes the caregiver feels uncomprehended by the patient and we are the ones that also suffer a lot. My wife says she just wants to be free and catch up with the years she missed while on treatment, it hurts me badly. And there’s nothing I can do about it other than to wish her health, luck and to let her go. I’m desperate looking for answers and I’m glad to read I’m not alone in this, other couples that have gone through cancer experience the same problem..

  15. Wow have I learned a great deal on this site! I had a close friend who had been on Chemo for awhile. She was a tough advocate for justice and a trusted and much loved team player, Very suddenly, and dramatically, she decided her best friend was trafficking drugs and having affairs with Black men. No amount of reasoning and truth could enter her convictions. Very tragically, her convictions were contagious, and much damage and hurt was created. I have been in shock and disbelief about this until now. Thank you for the insight.

  16. All these post are giving me so much insight! Knowing that I am not alone in seeing a loved one with cancer turn so angry toward those who are so close to them.
    My hubby, stage 4 colon cancer. He has become so irritable lately. I really have to keep my mouth shut. Nothing I say or do is right in his eyes. It’s tough. I see him getting physically weaker and his mind is confused about different things.
    I hope he finds his inner peace soon.

  17. This article has helped me understand so much of what my husband is going through .I will be making him several appointments in the morning. Thanky you, thank you, thank you

  18. I was an oncology nurse for thirty years and I could help most pts through anything. The one thing I would say is after chemo you might feel really crummy so give in to it, watch a movie, just look out the window,start at the ceiling and certainly ask your dr for medication to help you through this period. Later when both my parents developed cancer, I could help them, both in their own ways. My dad loved to walk through his garden, my mother wanted everything done for her ten minutes before. My sister who has an angry personality,still exploded, but space movies helped her,she went so fast, I didn’t have time to get my thoughts around what she was going through. My best friend developed a fast growing brain cancer and I would just sit by her and look at magazines, not talking as she couldn’t handle stimulation. I miss her so much. My cousin developed als and was misdiagnosed so many times, I spent a month with her, just sitting..
    I have cared for children with cancer, they are so joyful and I have never seen one depressed. Adults don’t seem to get down if they have some one sitting with them, not talking ,just sitting. Most children move now away from home and that is sad and even if they are close, they work, sports school etc etc. they don’t hold your hand.
    My one daughter in law had cancer of the spinal fluid and tomrelease thempressure in brain, themdr put a shunt in tomdrain into abd which only brought cancer cells throughout her body. I can only pray her personality change was due to the chemo as she called me evil and said I thought I was sick,needing scolosis repair badly,but I was wrong, she said I was making everyone around me sick.
    I would suggest people journal. They can sound off to paper anyway they want. Also it might help to give them an hour or so to be grumpy and then you didn’t want to hear anymore of it.
    A break for an hour or so might help if someone can come in from your church. The caregiver needs to get out and have a form of escape also
    Illness can hurt both ways.

  19. I was also a cancer patient, currently in remission. I can really say that I find this article quite useful.right after my chemo,I had serious anger issues,I would get mad at anything, I was really angry and very depressed I couldn’t understand why,but lucky enough I was able to come across this article,and its been advice to patient relative is to be patient and strong for your loved one suffering from cancer,I remember when I use to speak rudely to my mum,but each time she keeps comforting me,and now that iam better I appreciate her more than I did before ,and even when I had reoccurrence before my current remission, I tried to behave,but it was not easy I could say I was boiling inside.

  20. Why don’t doctors tell you this???? My dad has been taking chemo for almost 2 years and this anger and explosive behavior has been going on for months now. He lashes out at everyone at tiny things one minute and is just fine later. He has seen many doctors for his liver cancer and NONE have mentioned this to us. The nurses ask if he has any depression and of course he says NO! I’m JUST FINE! We shake our heads No he isn’t. So he has some mild medication for depression. But it isn’t enough. So glad for all these comments. THANK YOU. Well will be addressing them at his next appointment!

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