Hi All,

Can anyone help me, I am going to be taking tamoxifen but I am on SSRI Antidepressants, I have been told that these Antidepressants reduce the effectiveness of Tamoxifen, I am really concerned about this as I find it difficult to change Antidepressants and cannot come off of them due to the severity of my mental health, but I want to be sure I am getting the full effect of Tamoxifen has anyone else come across this as I am very concerned.

Debh x

You don’t mention which antidepressants you are on. I was suffering horrendous hot flushes due to Tamoxifen and Herceptin last year so my doctor prescribed a low dose of Venlafaxine which has helped to cut them down. I don’t know whether that belongs to the SSRI group of antidepressants or not.

Obviously the dose I am on is very low as it isn’t for depression, just flushes but there are a lot of ladies on the forum who take antidepressants whilst on Tamoxifen so I am sure you will be able to combine the two if you speak to your GP.

Hopefully some replies will be forthcoming soon.


Your medical team (Oncologist/GP/Specialist) will make sure you are on the right kind of antidepressant whilst taking tamoxifen I am sure. In order to be fully effective, tamoxifen must be metabolized to an active metabolite, endoxifen, by the liver enzyme CYP2D6. Certain SSRI antidepressants are inhibitors of this enzyme & might reduce the conversion of tamoxifen to endoxifen, thereby potentially reducing the efficacy of tamoxifen. Your GP will hopefully discuss this with you and find the best treatment possible for you. xx

Quick one as I’m off out in a mo. fluoxetine (Prozac) is the problem SSRI but others such as venlafaxine and citalopram are fine as they are metabolied differently .

flouoxetine (prozac) and paroxetine (seroxat) are the two SSRIs that are actually documented to have a problem and should eb avoided on tamoxifen… its not a definite interaction and only a small percentage of people will have an interaction but because they dont know who that is they recommend that you dont take prozac or seroxat at the same time as tamoxifen.

“metabolism of tamoxifen to active metabolite possibly inhibited by paroxetine/fluoxetine (avoid concomitant use)”

venlafaxine isnt an SSRI btw.

Maybe you find this link helpful:


Hopefully your oncologist&GP will prescribe the most appropriate treatment for you, please don’t worry!

Hi Tina46,

Thank you for that, I have followed the link and it looks like mine should be safe,very useful site.

Debh xx

Lulu, it’s an SSNRI (see, I do read the leaflet that comes in the packet! :wink: ) but it’s a SIMILAR drug and used for the same conditions. I forgot about Seroxat, thanks for the reminder.

Oh heavens. I was on fluoxetine whilst on my 5 year tamoxifen stint. It must have worked because when I finished the Tamoxifen at the end of Sept I noticed hormonal changes to my body ( felt like it had gone onto overdrive). No one said I shouldn’t be on both…oops

Twinky x

twinky its a relatively new finding and many docs arent aware of it… think its only been discovered to interact in the last 2 or 3 years… and as its not everybody i dont think its one of those things taht ping up at the pharmacy when you collect your prescription.