Hi
I have been struggling with the side effects of Tamoxifen and just wanted to hear from other people with a similar experience and any solutions that you may have.
I had a lumpectomy in December 2025 for a grade 2 invasive ductal carcinoma. I was then given Tamoxifen end of January and had radiotherapy in March.
Initially I found the tamoxifen was bearable but over the past two months I have suffered extreme mood swings and debilitating brain fog. I don’t even recognise myself. I saw a GP who told me that mood swings weren’t a side effect of tamoxifen (extremely unhelpful!) then spoke to breast care nurses who said come off for 2 weeks then go back on for 12 weeks to see how things are.
I am now 1 month into retaking it and the mood swings and brain fog are back. It’s like I’m not in control of my body and I flip out at the slightest thing which is very unlike me pre tamoxifen.
I’m 34 years old with 2 young children and I don’t want to risk a reoccurrence but I am starting to feel that my life is being so severely affected by this drug that I the risk is outweighing any benefit it might have.
My next step is to speak to the oncology team again and they said they might refer me to a menopause clinic for advise or suggest anti depressant (which I really don’t want to take only to counteract the effects of another drug) However I’m struggling to see that anything is going to counteract these horrible side effects.
just feeling very helpless with this if I’m honest, so reaching out for some help/advice. Has anyone made the decision to stop taking tamoxifen? Has anyone been prescribed anti depressant but still on tamoxifen and felt better?
Xx
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Has anyone told you how much benefit this drug is taking you? You could put your details into Predict to how much it enhances your reoccurrence risk.
I came off letrozole for similar reasons but at 58 with adult children it was probably an easier decision to make.
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I’m 54 and just started Tamoxifen, lumpectomy and radiation done, was on letrozol until now as I had to wean myself off a very low dose of fluoxetine before I could start tamoxifen… it has been a nightmare. I have a history of depression and had to come off HRT after diagnosis but this is worse. The brain fog is debilitating. I am constantly weepy and furious and sad. I have been prescribed an antidepressant (agomelatin) but I am wary of being on a cocktail of drugs. I’m also interested to know if anyone has had a good experience with antidepressants and tamoxifen and am also just here because I don’t know where else to go. This is my first post, btw, so hello everyone!
Late reply and I hope u are feeling better. It is a horrible horrible situation and decision to take.
I haven’t yet taken tamoxifen (need to do radiation first) but I have been dreading it from the day I got my diagnosis (I’m a pharmacist working in oncology so I had the idea what I’ll be getting into) precisely for the side effects you are mentioning.
My cancer was small, low grade, low proliferation and I even got conflicting opinions from oncologists (some saying benefit is too small for me to even take it, others (including MDT decision) being firm to take it). I will try it but if I end up having debilitating side effects that severely impact my quality of life and have to be managed with more (serious) drugs I will quit, and I have already told this to my medical team and they were ok. After all- tamoxifen is only giving 40-50% lowering of the recurrence chance, not 100%. But it all depends on what is your baseline chance and how much you are gambling if you quit.
Now- I am basing my view on the very low Predict benefit and the specifics of my tumour (after all I also have an opinion of a highly recognised international expert not to take tamoxifen because of how my tumour is)….have you tried to get a second opinion? Or run Predict? It might help you.
Btw. I am 41, and my age is the only reason why I am willing to give tamoxifen a try. If I was 60, 65 I would not even bother and would happily take my (very good) chances without hormone therapy.