Anyone bleeding on Tamoxifen?

I’m pre-menopausal and have been on Tamoxifen for 5 months. I had a slight bleed shortly after starting on this drug but no periods since until today when I started to bleed quite heavily.
Has anyone else experienced bleeding whilst on Tamoxifen? My BC consultant said that ‘unusual’ bleeding could be a sign of cancer of the endometrium and my GP told me I shouldn’t bleed whilst taking the drug.
How are we supposed to differentiate between random periods and ‘unusual bleeding’??
Now unsure whether to ignore it or make yet another trip to my GP!!
Any advice would be gratefully received please.
love Gill x

Hi Gill,

I have been on tamoxifen for 14 months and have a heavy, regular (every 28 days ) period. Last year my onc said some women stop completely, some have regular ones like me and some are intermittent. Both my onc and consultant still seem to think the tamoxifen is doing its job and it’s not a problem, although I get a little worried thinking about all the oestrogen flying around my body! I too am pre menopausal (age 45).
If you are worried go back to your GP or ring the breast cancer care helpline as they may be able to help you.
Let us know how you get on.

Take care
Shorty x


I’m exactly the same as Shorty - have been on Tamoxifen for 9 months and my periods have shown no signs of stopping whatsoever. My GP and consultant don’t seem too troubled by this either. I’m 38 and premenopausal.

All the best,

Sally xx

yep - I’m 40, premenopausal, been on tam since late Feb and have had a slight period every month depite the combined effort of tamoxifen and a mirena coil.

However I would say go get it checked out just to be sure.

Same here been on Tamoxifen now for 14mths and have heavy and sore periods which are very irregular … every time they are late (14 days today) I keep wondering of thats then gone, but i have so much pain i think they are coming!!! Oh im 41 and also pre-menopausal.

Allison x

I am 38 and premenopausal and I too am confused as to what is going on with my body. I have been on Tamoxifen for about 14 weeks. I had no change to my periods for the first couple of months but for the last few weeks i have had a period every two weeks. Was going to seeks advice at next appointment.


I am also premenopausal been on tamoxifen since february, period every month is getting worse…

Hi all

I have been on tamoxifen for about 10 weeks and had 1 period!!

Reading all your posts we are all so diffferent dont understand!! confused with it all!!

Hi all

I am 41 (diagnosed 37) and have been on tamoxifen for 2.5 years now and still have regular 28 day periods, they have never stopped not even during chemo. I do worry to that some women are on zodex or have their overaries removed but I have just had tamoxifen, I am going to ask my onc at next appointment why that is unless anyone else knows, I was a grade 3 with 2 nodes positve and a 5cm tumour, er+


Hi girls
Thanks for all your replies!
It does indeed seem that we all have different reactions to Tamoxifen.
Still don’t know how to distinquish between ‘unusual bleeding’ that must be reported to GP and a period!!!

Good luck to you all
Love Gill x

Hi Gill

Please feel free to call our helpline or use our ‘Ask the Nurse’ email service to find out more about your query, the number to call is 0808 800 6000 Mon-Fri 9am-5pm and Sat 9am-2pm, the ATN service can be accessed via the ‘Support for you’ tab at the top of this page.

Best wishes

Hi, ive beenon Tamoxifen for over a year and have a very light period approx every 6 wks. chemo didnt stop my periods and onc doesnt seem concerned

Hi I was on Tamoxifen for 1 year and no period in fact nothing since first chemo in 2006, I am 35 and pre menopausal but the spotting I experienced a few weeks ago turned very very heavy and I was admitted to a maternity hospital through and given a d and c for thickening in the womb, I have since started Arimidex even though I am not having Zoladex and all fine so far, But I must admit I am a little concerned about ER/PR production from the ovaries… but I would get any irregular bleeding checked out

Hey guys,

I have been on Tamoxifen for nearly 5 years (light at end of tunnel…) my periods are fine and never stopped.