Side effects of Tamoxifen compared to Letrozole

Welcome to the forum Ronnie .There are certainly ladies on the forum who have swapped to Tamoxifen from Letrozole and found it easier to live with but everyone is different .You have done 5 years -so you have done a lot to help stop a re-occurrence already -a lot of ladies make a decision to stop meds because the side effects are so detrimental to their quality of life - very difficult decision .Jillxx

You have my greatest sympathies. If it happened to a man they would have sorted it out by now for sure!


Interesting to read…

I’m on Letrozole & Iasibon but the Letrozole is causing me extreme pain. Had chemo then lumpectomy and full node clearance got all clear then 15 sessions rads. Still on Herceptin actually going thus afternoon for my 3wkly treatment on it until end October.

Side effects Letrozole horrendous so I’m taking a couple weeks break as told by BC Nurse to see if pain stops to put me on tamoxifen instead. Hip legs pains headache stiff sore fingers and get out of of a chair like a 90yr old… ??

Is tamoxifen easier? Or would I swapping for same? I’ve been on Letrozole for 2 months but I wonder if some of my pains is still chemo after effects.

Nothing feels easier the pain is torture ??


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Hi Sue,
I’m on tamoxifen, I could go onto anastrozole, but as I’ve been fine on tamox, my oncologist & surgeon were happy for me to stay on it. The onc told me that tamox is protective of bones & I have read that it acts like hrt on bones & the cardiovascular system in post menopausal women.
Technically, my understanding is that AIs are more effective, however, I did read some research that there wasn’t a lot of difference in overall mortality rates between the two.
As my father has poor mobility from osteoporosis of the spine, I was reluctant to change in my situation, unless there was a very good reason to do so. At my last yearly check, the surgeon was happy with this.
Wishing you well with it all
ann x

I’ve been on letrozole for 2.5 years post breast cancer surgery. No significant symptoms EXCEPT bone loss!! Now I’m osteoporosis and I still have at least 2.5 years to go. I’ve taken the Prolia shot to help with the bone loss and now am considering switching to tamoxifen. My main concern is side effects of tamoxifen as I’ve had very little with the letrozole…except of course for the bone loss which now is my main concern. My oncologist is willing to switch me but is also concerned with the side effects. Thanks for input.

Hi Humblehand,
Just to say that side effects with tamox are not necessarily a given, but as ever will tend to get talked about. I’ve been on it for 2 years now without any problems & many of us are ok on it.
In view of the osteoporosis, it may be worth a try to see how you go.
ann x

Hello Humblehand ,welcome to the forum.Everybody is different in terms of side effects ,Some are lucky and have very few from Tamoxifen .The most common side effect seems to be hot flushes .Tamoxifen can cause changes to your womb lining so gynae issues can be a side effect and you need to get any changes/ unexplained bleeding checked out The other side effect I had was leg cramps at night .Side effects do seem to vary depending on the brand of Tamoxifen (some people seem more sensitive than others) ,so it may be worth experimenting to see which suits you best - Teva brand seems to be generally well tolerated by most people but it does vary .Good luck !! Jill x

Good luck with whatever decision you make.Yes ,this is a great forum, lots of advice and support from people who understand .

Hi everyone,

Ive been on letrozole for 3 years but was also taking steroids for polymyalgia. Finally stopped the steroids in February and then boy did the aches and pains set in. The steroids had been masking the side effects of the letrozole .Eventually my BN told me to have a break for 2 weeks and pains more or less disappeared. Started  exemestane last Wednesday and by Monday this week I am back in pain. My yearly oncology appointment was today and I’ve been told to have another 3 week break then try tamoxifen. After reading comments can’t say I’m looking forward to this one either. He told me it didn’t have side effects of aches or pains but did have hot flushes and weight gain ? can anyone tell me the best brand so I can speak to the pharmacist.

Fingers crossed , just hope the weight gain is not too bad, my daughter gets married in August and I need to get into my outfit ?


I have had wide local excision and removal of several lymph nodes, which were clear, then 15 days of radiotherapy. Have been on Letrazole for about 3 months and off work. Initially suffered terrible aches in left knee and ankle - both sites of previous sports injuries. Since then have experienced great pain in both ankles and feet, and swelling of feet. Can hardly get out of bed in the morning. Hobbling like an old woman whenever I get up. Miserable! Suffering shooting pains in feet and right breast at night. Feet have increased a size and a half. I don’t want to live like this for 10 years, and I don’t know what to do!

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Yes I was on Tamoxifen for 3 years, switched to letrozole for 3 years and now just started back on Tamoxifen for a further 3 years. I think the idea of switching is to try and limit the side effects and to also stop the body getting used to the drug. This strategy seems to be working well for me so far!

I started off on exemestane and zoladex injections as I was still considered pre menopausal but found the joint pains horrendous. After 4 months swapped up Tamoxifen plus zoladex. Just having a 3 month break from zoladex to check my hormone levels so that can stop them altogether if am now post menopausal. I still have achy joints but nothing near as bad as the exemestane main side effects are the hot flushes and interrupted sleep they cause. I would give Tamoxifen a try if I were you. Good luck x

Hi All, i have been taking letrozole for 6 months and i am struggling! My feet and knees were the worst at first and i still have to stand for a minute before walking. However Skechers shoes seem to be helping. My biggest problem now is my shoulders. Both are bad but my right, surgery side, is the worst. I can fasten or unfasten my bra, i can’t reach sideways or reac up and i struggle to wrap my towel around myself after a shower. It fells like my shoulder is going to come out! None of the medics put thos down to Letrozole but i definitel feel it is xx

Hi Appletree and thank you for sharing tbat very useful information! I spoke to my BCN and she is sending me for a bone scan just as a check. I told my oncology nurse and she said its ‘disappointing’ that i am not exercising!! I know they have no real understanding of what we are going through. I think they should come and read this forum!! Xx

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i had been on Tamoxifen for 8 years and will switch to Letrozole as one of my seconday breast cancer (BC spreaded to sternum) treatments.

to me, tamoxifen side effects is nothing. only hair thinning and slow growth (need hair cut once every 9 months). This side effect vanished soon after tamoxifen is stopped.

 I only worry the two side effects due to Letrozole. Hair lost - will be on Letrozole for long term. I really can not accept bald head for that long.

osteoporosis - my onco will give me the bone strengthing medicine Bisphosphnates My cancer dentist in hosipital told long term letrozole may cause osteoporus. However, i am so scared of  Bisphosphates foe which the side effect jaw osteoporus. From the postings in this forum, some even had the bone fell apart from the gum.


randomly read an article Letrozole is better than tamoxifen for preventing  recurrence.


 "At an average follow-up of more than eight years, postmenopausal women who took Femara for five years after surgery were 20% less likely to have their breast cancer return and 21% less likely to die from their breast cancer compared to postmenopausal women who took tamoxifen.

The drugs work by blocking the production of aromatase, which turns the hormone androgen into estrogen in the body. But because they don’t stop the ovaries from making estrogen, they are not used to treat breast cancer patients who are still ovulating."


My last period was in 2011 during my cycle 2 chemo. They still considered me pre-menopause and so let me take tamoxifen. However, i am now menopause and no choice but only  letrozole. 

by the way, i am not aware there are several brands of temoxifen. i have my chemo treatment in Bristish Columbia, tamoxifen is provided by the goverment. It is free, covered by our medical system. and is of one only brand TEVA


Hi ann-m

I’ve also been on Tamoxifen for 2 years and am due to switch to Letrozole soon for a further 3 years. I know some people get bad side affects but for me the Tamoxifen has been absolutely fine. Joint stiffness and hair thinning initially but it settled down. I’m really worried about switching as Tamoxifen seems to suit me. I’ll soon be 57 and wasn’t quite through menopause when I started on it. Now I’m certainly post menopause I probably need to switch to Letrozole
but I’m very apprehensive about it.

Hi I started Letrozole last March but had all the side effects many have stated - brain fog. vaginal dryness & awful pains in joints.
I switched to Tamoxifen in September and all of those things resolved. Yes I still have sleep problems & hot flushes but overall I feel so much better.
My consultant was wonderful & listened to all my woes so talk to the clinic and see about swapping ?

Just today switching from Letrozole (on it 1 1/2 months and side effects daunting).
Convinced ONC to switch me to Tamoxifen.
I HOPE it has less side effects.

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I am 76 and have been told I will be put on Tamoxifen, but do not want to take it because of of all the side effects. It’s a dilemma, so I am trying to get opinions how people went on who decided not to take it.

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