Starting Tamoxifen: What are the Side Effects

Hello, I will be starting Tamoxifen in about a month's time. My doctor advised to take aspirin everyday as there is a risk of developing blood clots.

Have you been taking aspirin with Tamoxifen? What are the usual side effects that you've experienced?


  • ata
    ata Member Posts: 7

    I had an unusual food allergies, especially the allergies for food with fructose in it.

    I did not take an aspirin.

  • paloma1211
    paloma1211 Member Posts: 95

    I took Tamoxifen for about a year (before I switched over to Anastrozole), and I didn’t really have any side effects. Maybe some night sweats, but that’s about it. Hopefully, it will be really easy for you,

  • heikedog
    heikedog Member Posts: 1

    I've been on Tamoxifen for 2 years now. The main SE I have had is severe leg cramps at night. My oncologist suggested 400 mg of magnesium at night and this took care of the leg cramps. After taking the mag for two years I don't seem to need it all of the time. My onc never mentioned the aspirin but I will ask her next visit because I worry about blood clots.

  • moderators
    moderators Administrator Posts: 6,559

    @heikedog, and all! Welcome to the community. We are so happy that you have joined us and hope that you will find it a supportive and encouraging place. You may find some helpful information on blood clots in this article of our main page: Blood Clots and Phlebitis

    We hope this helps! We look forward to hearing more from you soon.

    The Mods

  • hn
    hn Member Posts: 23

    Thanks all!

  • momgoose
    momgoose Member Posts: 47

    I'm on my third month of Tamoxifen. I have some joint pain here and there and muscle cramps, as someone else mentioned. 400 mg of Magnesium a night before bed makes a HUGE difference and lets me sleep so much better. I do feel like my thinking is slower than before. I find myself searching for words quite a bit more and just feel like I am struggling to think. I can't really attribute it to anything else, as I did not do chemo and I'm "only" 44. But overall, I think I am tolerating it quite well. Don't be afraid. If you have night sweats, Effexor seems to be really effective as well.

  • salamandra
    salamandra Member Posts: 662

    This is incredibly varied. Common side effects include hot flashes, joint pain, and heartburn. For me, I had mild to medium versions of that when I started. I needed prilosec for the heartburn for a while, but eventually they all cleared up as my body adapted. Some women never have any side effects. Some women have those side effects but in a much less tolerable way, or that does not stop. Many women have more unusual side effects. (I also had fatigue, which did not go away, and was the main reason why I ended up changing to a different SERM).

    My doctor did not advise aspirin, but recently when I was having a set of other procedures that also raise blood clot risks, she advise me to go off toremifene temporarily to avoid stacking the risk.

  • hn
    hn Member Posts: 23
    edited May 5

    I am starting Tamoxifen in about a month so will see how it goes. I have always been kind of medicine avoiding person (with the thinking that medicines are not always good for body ) and now have to start this so it has kind of left me feeling upset. I will post about my experience.

    Thanks all.

  • corinner
    corinner Member Posts: 1

    I'm on week 2 of tamoxifen the hot flashes and depression are difficult for me to manage right now. Prior to my cancer diagnoses I was diagnosed with depression, anxiety disorder, ptsd and borderline personality disorder which I was already struggling to live with so I wonder if all this is impacting me. Nausea happens sometimes but gravol has helped that. As far as feeling upset that you have to be on medication, you don't have to it's your choice.

  • weninwi
    weninwi Member Posts: 377
    edited May 20

    I was on Tamoxifen for about 3 years with no significant symptoms, but I worried a lot about developing a DVT (deep vein thrombosis) so did everything I could to minimize the risk. I have mild venous insufficiency and have worn knee high support stocking for years so I knew this would help. I made a point of not sitting for more than two continuous hours before getting up to walk around or do a some leg squats. This is especially important when traveling in the car for long road trips or when flying. I made a point to stay well hydrated. I asked my MO about taking lo dose aspirin for prevention and was told "No". It is my understanding that tamoxifen's effect on clotting is not prevented by aspirin. I followed this advice as I really didn't want to take a daily aspirin, even lo dose, given the GI risks. During the 3 years I was on Tamoxifen had about 4 ultrasounds after episodes of persistent calf pain. Each time I reported the calf pain my MO referred me for an immediate ultrasound of the affected leg. The risk for DVT is taken very seriously. Thankfully, I never developed a DVT.

  • salamandra
    salamandra Member Posts: 662

    Hey corinner,

    I also deal with some mental health issues that predated my cancer. It turned out that my cancer center has a mental health unit with psychiatrists and staff who are specialized in supporting cancer patients - and which my health insurance shockingly actually covers! Just wanted to flag that in case that is an option for you or someone else reading this board. It has been great to have a doctor monitoring my meds who is really familiar with the physical and other side effects of the breast cancer experience and treatment.

  • mbinder68
    mbinder68 Member Posts: 1

    You just mentioned my biggest concern. I’ve had several major depressive episodes in my life and I’m on maintenance meds. I’m at the point in my life where I don’t have periods so my biggest concern is interaction of tamoxifen with fluoxetine and buproprion. Will I need to up my dosages or go to new meds? Either scenario is a big deal for those of us with mental health issues.

  • salamandra
    salamandra Member Posts: 662

    Hi Michelle,

    I take buproprion and the issue with tamoxifen is that buproprion may lower the efficacy of tamoxifen. My oncologist advised me to try a different antidepressant (if I wanted to do tamoxifen) or to do OS/AI (if it was important to me to stay on buproprion).

    I tried tamoxifen with a different antidepressant. The other antidepressant was ok, but tamoxifen was a no go for me. I ended up on toremifene which is a sister SERM drug that is not impacted by buproprion, and I was glad to go back on my generic wellbutrin. I wonder whether toremifene or a different SERM could be an option for you?

    Otherwise, you might decide to do tamoxifen and stay on your meds knowing that the tamoxifen might be less effective than otherwise and hoping there is still benefit; or to try different meds - but that's not an option to be taken lightly considering the risks, and a good oncologist will understand that.

    Hindsight is 20/20, but if I'd had the chance to take toremifene as a preventative, I hope that I would have. As it happened, my genetic test results showing 57% lifetime chance of breast cancer came back at basically the exact same time as my actual cancer diagnosis, so that was not an option.

    It gets trickier if you try it and end up having actual side effects you have to way against potential benefits, but at least then you have that info.

    Good luck with the testing and with your decision!