Arimidex Side Effects

I know that some of my questions have already been discussed under different threads under this topic, but am putting it up as a new query in the hope that some new members may be able to help.
Have been on Arimidex now for 2 1/2 years following a recurrence. Originally was treated with Tamoxifen, but stopped due to serious side effects to my eyesight and then had a recurrence 4 years later, so this time it was decided that Arimidex was a better bet for me.

Now have developed very serious side effects: Apart from severe muscle pains and night sweats, which have prevented a decent nights sleep for over 2 years (despite sleeping pills), have now had full MOT and was found to have very high cholesterol, severe underfunctioning thyroid, just gone into oesteopenic range, poor liver function. I am very loath to take further drugs, i.e. statins because of their proven side effects (more muscle pains??) Can’t have Biphosphorates because of bad reflux diseases which has already efected my oesophagus.

I should add that I was very healthy (apart from the cancer obviously) before starting Arimidex. I am in the normal weight range, have plenty of exercise and eat a very healthy and low fat diet and my cholesterol was always around 3 , I never had colds and flu and was very rarely unwell. I take loads of supplements, both for the joints and to stregthen bones (CAlcium & Vit D). My GP agrees that almost all the side effects have been recorded as being present in patients on Arimidex , apart from the thyroid problem in me, which may have been present before - but is also now being reported as a side effect. I am already taking Thyroxine, but sofar with no efect on lowering my TSH levels.

My query is therefore, should I just stop Arimidex? I will see my oncologist again in a fortnight to discuss further, but in my own mind I think I have already decided that quality of life comes over quantity. However, it is not just me, my kids don’t want to lose me and nor does my husband. But my quality of life is so poor now that every aspect is affected. And if I am honest, I am also questioning the long term benefit of Arimidex, as I have already had a recurrence and spread to all lymph nodes despite treatment , so Arimidex is at most giving me a bit more time.

Sorry, if I am a bit moany, but I really find this such a difficult decision to make. Hope some of you can help with your wise and helpful words.



Hi Birgit,
Sorry to hear you’re having bad side effects from arimidex but I can certainly empathise!
I’ve been on arimidex for 18months and for most of that time have been experiencing severe joint pain and stiffness (hips and lumbar spine)… chronic tiredness… severe vaginal dryness… hot flushes and night sweats… I’m well into the osteopenic range and over the past 5 weeks have had headaches very day.
This time last year I took a 2 week break from arimidex and then tried both the other aromatase inhibitors…I didn’t fare any better so went back to arimidex. I’ve now had another 2 week break coz things were getting so unbearable and now I really don’t know what to do…I have begun to feel better as far as the joints go and am loathe to go back BUT I would never forgive myself if I went on to develop mets…I’d always think “if only”…like you I also have my family to consider.
I think I’m going to try aromasin again…when I tried it last year I’d not long finished chemo and rads… so it might be differant this time…fingers crossed!
I have an underactive thyroid (diagnosed 4 1/2 years ago) and it took at least 6 months to start to feel back to normal…it is unlikely that you’re even on the right dose yet, it has to be increased slowly from a loading dose… it took months to get to a dose that was right for me.
Don’t know if this has helped.
Claire x

Hi Birgit and Claire
New to using this site and very interested in finding out about Arimadex and other options for hormone treatment.DX 2yrs ago but due to pre-existing heart condition and ongoing medication and surgeries I was dismayed to find that the therapy originally suggested for me to take,following my mastectomy’ Arimadex, was now not a good option as the view was that it might cause me increased cardiac problems. I was told it was upto me whether I wanted to take it- as I was told Tamoxifen was not a good option due to a previous pulmonary embolism- I was left on no therapy and not really informed enough to ask the right questions. I too have a child who I want to be there for for many years and am increasingly frightened that by not doing my best to get the right treatment to hopefully prevent recurrence, I will continue to stay in the state of fear and helplessness I find myself in. I am due to have discussions with the oncologist about this once the BCN has collected information from my cardiac team. I need to hear from anyone who has had to face this choice and anyone who can give me the information I need upon which to base my discussions with the BC team - I so need some help at the moment.

Hi serendipity

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Breast Cancer Care

Hi Claire and Serendipity. Thanks for your replies.

To answer your questions first, Serendipity, Arimidex can have side effects that affect the heart and I therefore assume that your team has weighed this up when deciding not to offer you this drug straight away. It is unfortunate that they have put the choice onto your shoulders, after all, you are not a medical expert and not really in the best position to make such a decision. However, the decision you can make and discuss with your team is this: If the Arimidex is to be given in an adjuvant setting (i.e. not to treat any existing cancer) what are your possible chances of recurrence if you do not take it and what risks are involved with regard to your heart. Of course, sadly, nobody can give any guarantees, otherwise everyone on Arimidex would not get a recurrence or develop secondaries. So bear that one in mind. If your prognosis is very good, you must really decide whether you are prepared to take any chances with your heart condition, which could ultimately be far more serious then a recurrence. I know this is probably not the answer you want to hear and I also know that a lot of the girls on this site would be adamant to take anything that would give them even the slimmest of chances to prevent a recurrence, but ultimately this must be your decision based upon the advice given to your by your team. To many of us, quality of life is more important and I probably fall into that camp, but everyone is different, their lifestyls are different, their family responsibilities are different and they may or may not have other serious medical conditions.

Claire, I too tried Aromasin, but could not get on with it I also tried Femara but had the most horrendous headaches and almost constant sweats, day and night, so like you went back onto Arimidex. I am seeing my consulant in 10 days time, but I think I have already made up my mind, as I think all the xtra drugs I would need to combat the side effects of Arimidex can only make things worse. But as I said, we all have to make our own decisions at the end of the day and that is the hard bit!

Good luck to both of you and thanks for replying.

Birgit, .

Hi Birgit

Thanks for responding it’s good to know there is someone out there who can offer their perspective on things.

Don’t know if this helps but will just recap my experience with arimidex. Been on it for 4 months, after 6 wks was is terrible pain, mostly legs and all joints, esp feet. Had routine app with surgeon so mentioned it. She pursuaded me to keep trying as these s effects can wear off. 6 wks later they had decreased so much I am staying on it, BUT, at the same time I had started weightwatchers, lost 1.5 stone, and was exercising daily.

In the last 2 wks I have been away from home alot, been eating and drinking wine more and gained 3 lb. I now have all the aches and pains back again. I think it is prob the wine with me. Trying to get back on track this wk so will report back if things improve again. I will then be able to def pin point the additional issues that add to cause the pain.


oh dear …I think I might have to make a appointment with my oncologist!

I have been on Arimdex for 3 months (after 8 x taxotere for recurrence) and so far the hot flushes are the same as tamoxifen which I was on for 3 years in 2004 and the aches and pains I have have been blamed on chemo. Other than that; nothing too grim but I will be having my cholesterol checked next week…

I am seriously thinking of coming off Arimidex so was very interested to read all your comments. I have er+ and her2+ breast cancer - I haven’t had chemo so can’t have herceptin, not that I would accept chemo anyway. The way I feel it would just finish me off, so the Arimidex is only dealing with part of my problem. I get the impression that you are all younger than me - I’m 69 and don’t have young children so quality of life is that bit more important than quantity. I don’t have aches and pains but have lost my appetite which is pretty devastating as I used to love my food. I am steadily losing weight which I can’t afford to lose and my onc has termed me anorexic. I have to literally force myself to eat. So, I can either stay on the Arimidex and have rotten quality of life (no energy, not sleeping) and perhaps the anorexia will finish me off, or I can come off the Arimidex, have a decent quality of life and maybe the cancer will finish me off. Unfortunately the bottom line is that the decision is up to me - a really horrible position to be in.

Hi Valanne

I am sorry you are having such a difficult time, please feel free to contact our free phone helpline on 0808 800 6000 if you would like to talk to someone in confidence about how you are feeling at the moment. Everyone on our helpline either has experience of breast cancer or is a breast care nurse. The team comes from a variety of backgrounds, so callers get to talk to someone who has an understanding of the issues they’re facing. The team is able to talk about both technical and emotional issues surrounding breast cancer and breast health. The lines are open Monday to Friday 9am - 5pm and Saturdays 9am - 2pm

I hope this is of some help to you.

Kind regards
Jo, Moderator

Hi everyone, I’ve just switched to Arimidex (a month ago) after taking Tamoxifen for a year. Switched because of the horrendous weight gain (2st in a year), onc though Arimidex might be better. But having many more joint pains than I did with Tamoxifen, and now headaches, and feel so tired most of the time - really just like a dose of flu! Not sure what to do, but am off to Living with Breast Cancer course in Derby next week, so will be firing my questions to the experts! Will let you know how I get on.

Jean xxx

Hi Girls

Quick update - Seen oncologist on Tuesday, having had long discussion with GP. After a very lenghty wait (over 2 hours) and me getting more and more agitated, thinking the guy is going to be stressed and does not want to listen, it went extremely well. Having listed the side effetcs, with printed copies of all blood tests, scans etc. in case they did not have details on computer, and ready ‘to do battle’, he actually susggested to discontinue Arimidex! I was speechless. Apparently, and do not quote me on this, the main effect of all Aromatose Inhibitors is in the first 2 to 3 years, after that it slides off gradually. He was throwing various ‘percentages’ at me, could not take it all in, but basically as I’ve been on them for 2 1/2 years, the possible long term risks to my health from the side effects, would outweigh the possible benefits from Arimidex. New research is being done on these ‘newish’ drugs all the time and it looks as though in time there will be a concensus of how long patients should take these drugs.

Now, before you all rush off to see your oncologist, obviously, like everything else with this disease, it so depends on your particular circumstance and whether it is given in an adjuvant setting or to actually treat existing tumours or secondaries. So for me, in any event, the worst is now over. I can now try and get my cholesterol down, try and improve my bone health , should be able to get upstairs again without pain and hopefully sleep for a whole night without permanent sweats etc.


Hi Birgit,
How long after starting on Arimidex did you start getting side effects. I know we’re all different but I’m waiting for something to happen, but nothing has so far(touch wood). Mind you I’ve only been taking them for a week.

Hi Birgit,

That’s really interesting. Good for you being able to extract that information from your oncologist. I have been on Femara ( also an aromatose inhibitor) for nearly 5 years now and get the impression that my oncologist doesn’t seem to know much about how long I should be on this drug or when it ceases to become effective. Like you, I have had an increase in my cholesterol level from 3.3 to 4.7 but because it is still in the normal range noone seems concerned. I was diagnosed with neuropaenia 2 years ago and take calcium tablets and vitamin D as I did not want to take fosamax at this stage. I first noticed hair thinning several years ago and will probably have to have a wig next year.

I have noticed that increasingly the words" There may be long term side effects "are appearing on the internet reviews of these drugs.

Like you, I would urge people not to just come off this drug without consultation as I understand that the aromatose inhibitors have been pretty successful in preventing further malignancies and it may be a question of balancing this against side effects.

Hi Marcos, Side effects were very gradual. First a lot of night sweats etc. then a few months down the line joint pain, then general memory loss and feeling tired and run down and then finally this year all the side effects listed in my first post. So obviously, there will be a gradual build up. But, and this is a big but, not everyone has all the side effects and if you don’t, stay on the drug for as long as possible. Just make sure you have your cholesterol checked and have a regular DEXA scan. It is always a good idea to ask for a DEXA scan at the beginning of trearment , as you then will have a base line to compare future results to. You may have to fight your corner on the DEXA scan as not all hospitals offer these routinely, but it is important that you know what your T score is, i.e. your bone density. Good luck.