Tamoxifen and tiredness/nausea

I had a lunpectomy 2nd March, radiotherapy 5 sessions from 28th April to 4th May.  I am 44 and pre menopause.  Started tamoxifen at end of march.  I take it every morning but it is making me very lethargic and I feel constantly nauseated.  I’m hoping to get back to work in a couple of weeks so can’t afford to be feeling sick and tired all the time.  I’m unsure if it’s likely to be from the tamoxifen or the radiotherapy and whether I should contact my GP

Radiotherapy caused quite a lot of fatigue for me for a few weeks afterwards and tailing off over time. It might be the last thing you feel like doing but regular exercise really helped. Can you do a phased return to work to build up your hours over time?

You could try taking the tamoxifen at night and see if that helps. I didn’t get nausea (but did on the first few months of exemestane), but it might be worth asking your GP or BC nurse about something to help with that. Most of my side-effects evened out after a few months.

Dear Ashley, 

I would suggest speaking to your BC nurse or even your oncologist.  I started taking tamoxifen in the morning,  but was advised to change this to take it at bedtime. 

You may be experiencing some post radiotherapy tiredness too,  and I would just say, listen to your body - if it needs a rest, just try to go with it.  It will pass. 

I hope this helps, 

Take care x


I also take tamoxifen every morning ( since March) but I don’t feel nauseated. I experience more ocular side effects - dry eyes, blurred vision and I find it a bit hard to work.

@ashley0611  - I just wanted to add one thing to the great advice you have already received. If you find one brand of Tamoxifen does or doesn’t suit you, you can always ask for an alternative. For some people the brand can make a difference with side effects. My GP is happy to specify my preferred brand on my prescription, and my local friendly chemist always tries to get it. I’ve been taking it for about 4 years now.

Also, it can take a few months for side effects to settle down - though it sounds as if yours might be settling already. I really hope it treats you kindly. Evie xx