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Tamoxifen Side Effects

How long were you on Tamoxifen before you started to notice any side effects? Also, what was your age when you started Tamoxifen


  • salamandra
    salamandra Member Posts: 727

    I was 39 and my side effects started in the second week, I think. Ridiculous heartburn (for high strength PPIs and it eventually went away) and fatigue (needed about 15 hours of sleep a day, it never went away)

  • veeder14
    veeder14 Member Posts: 268

    I started Tamoxifen at age 61. I noticed the Tamoxifen giving me heartburn, stomach pain about day 8 or 9. I still have this but not as severe most of the time because I take twice as much PPI medication. Within the first two weeks I began having major problems sleeping, and getting exhausted. No relief from that. After a couple of months I was diagnosed with a very thick uterine lining which menopausal women don’t want, so reluctantly had a hysterectomy to solve that issue and resume Tamoxifen. After several months I got dry eyes, dry skin. Two more years and I’m done with it.

    If anyone doesn’t have throat/stomach/heart burn when starting Tamoxifen I suggest protecting before you get it. The pills aren’t even coated and orally is the only way to take it

  • Jinx27
    Jinx27 Member Posts: 119

    Salamandra, when do you take your Tamox? In the day or at night? I was told by another patient that switching up the time you take it can help lessen side effects. I also experienced heartburn and had to be super strict with not eating past 7pm. I also have high cholesterol (LDL, HDL and triglycerides) I think that Tamoxifen is the culprit.

  • gb2115
    gb2115 Member Posts: 551

    I was 38, and didn't notice anything until I had irregular periods a few months in. The other side effects didn't start until probably 6 months in, and started with dry mouth/gum irritation. Eventually aches and pain set in, and severe vaginal atrophy probably at year 4-ish. Unfortunately tamoxifen failed me and now I've moved on to other medications. Looking back I didn't realize how good I had it on tamoxifen. Frying pan into the fire I guess.

  • salamandra
    salamandra Member Posts: 727

    aw Gb2115, I’m sorry to hear that.

    Jinx27, I took tamoxifen before bed because it was somewhat sedating for me. I take toremifene now and I still take it before bed, mostly out of habit. I should probably give mornings a try and see how that goes.

    I switched to cold brew coffee and cut out almost all spicy foods. Between that and the PPIs, the heartburn did eventually go away. I had another adjustment period starting on the toremifene but now I can drink regular coffee and not worry about spicy foods and am still fine, with just the occasional antacid. I hope things may still improve for you

  • delarbar
    delarbar Member Posts: 15

    Still in the pre-treatment stage. Prior to surgery this week I met with the Oncologist and she indicated I most likely would not need chemo. She discussed a good possibility of taking Tamoxifen for 5 years or longer.

    I do have acid reflux and GERD and after reading comments, I am concerned about how that will work with the Tamoxifen. I'm on Omeprazole as needed. Thinking I may need to start taking daily, reaching out to stomach doc.

    Anyone have prior stomach issues before taking Tamoxifen?

  • rah2464
    rah2464 Member Posts: 1,192

    delarbar - yes I definitely struggled with acid reflux. I cannot take PPIs because I am an intermediate metabolizer of Tamoxifen and PPIs use the same pathway. So I have been able to manage with some dietary changes and with chewing my calcium tablet after meals because you have to get to that 1200 mg of calcium anyway. I also take my Tamoxifen twice a day - 10 mg pills. Hope you find a solution that works for you as well.

  • tulletutu
    tulletutu Member Posts: 3

    I was 77 when I started and the side effects happened within 2 months. I am totally exhausted, it has drained my spirit. I use to love to cook and EAT, now I could care less, I only eat so my sister won't catch me in a lie about it. And of course, my legs are swollen and my hands ache and constipation, trying for the rhyme of some commercial that is rattling about in my head that ended with constipation.... My oncologist has said I have no other options as I am osteoporosis. I have an appointment with him in 3 weeks, but since by email he has more or less told me to march forward, I don't expect much

  • salamandra
    salamandra Member Posts: 727

    Hey tulletutu,

    Some women find they have fewer side effects on a different generic brand of tamoxifen. It differs from person to person so one has to try them out and see. I'm sure your oncologist wouldn't care about changing brands.

    But there's another drug, toremifene, that I ended up taking. It's also a SERM and has good evidence for it. If your doctor doesn't know about it and won't research about it, you should look for a second opinion. It has side effects as well, but for some people (like me!) my tamoxifen side effects were intolerable while my toremifene side effects are basically fine.

  • deweygirl19
    deweygirl19 Member Posts: 21

    I was 42 when I started taking it. It's been over 2 years now. Exhaustion and brain fog are the worst of it. I used to never nap, now I take a nap any time I can get one and still go to bed early. I never want to wake up, I could sleep in like a teenager now. Brain fog and forgetfulness is bad, I used to have a great memory but now I can't remember where I left my full coffee cup! My drs aren't much help, they just say to exercise and my energy will get better....... it doesn't. They don't listen just give lip service to get you out of the office for another 6 months.

  • rah2464
    rah2464 Member Posts: 1,192

    What I find is that if I have any additional stressor - allergies, something emotional, a deadline etc that my fatigue can overcome any attempts to sleep enough or exercise enough. I do find that walking a lot, even when I am feeling that wave of fatigue, does help quite a bit to push through. We have new puppies and I am walking 2-3 miles a day with them and I can feel a difference. But a high pollen count day can drop me right back into the fatigue. Coffee doesn't cut it at all. If I am truly struggling and I have to be awake I take a single 4 hour sudafed (the stuff you have to sign for). It will cut through the fatigue for a while. I don't do it often because I don't want it to stop working for me.

  • jbwarren99
    jbwarren99 Member Posts: 1

    Hello everyone,

    I was diagnosed with stage 1A IDC (two small tumors) in my left breast at age 48. I'm premenopausal. I've been on Tamoxifen for about 5 weeks now and I've felt the side effects almost immediately. I've gotten the dizziness and nausea. It Immediately turned off my period. I was a heavy flow person all my life and the first period after I started taking it, no bleeding. Just spotting which stopped then started again this week. I have pain in the front of my upper thigs and cramping pain and hot flashes and sweating. I take my pill at 11pm at night. I have made an appointment with my GYN for Monday because this cramping and spotting concerns me even though it's only been five weeks. It'll be interesting to see how the medication has changed my poor uterus.

  • rah2464
    rah2464 Member Posts: 1,192

    JBwarren - make sure you are staying hydrated especially with feeling dizzy. Triple Magnesium will help with some of the muscle cramping. What helped me the most was taking the tamoxifen 10 mg morning and evening. Also, at next doc appt make sure you are set for a bone density. Tamoxifen can be hard on premenopausal bone structure (it was for me). It isn't as hard on post menopausal bone structure.

  • gb2115
    gb2115 Member Posts: 551

    I found out after 4 years of tamoxifen that my bones were utterly trashed. I don't know how they were before I started though...I could have had preexisting early osteoporosis. In any event my MO was very surprised by this, saying that tamoxifen should have prevented that. I mean, I could easily read online that it's hard on premenopausal bones. How did she not know this? I wonder that sometimes, but it can't be undone.

  • cheftoast
    cheftoast Member Posts: 24

    hb2115 my original MO was surprised I had concerns about tamoxifen and bone health — I’m 47 and premenopausal. “Usually it makes it better!” he said. As you noted, there are tons of studies online to the contrary. For that and other reasons, I’m switching MOs. Meeting new one next week and have heard nothing but good things.

    I was so scared of tamoxifen I started at 5mg! Tomorrow I ramp up to 10mg, then 20 a week later. So far so good, but my stomach has been hurting, so helps to see all your posts. Guess I’ll add that to my list of questions.

  • rah2464
    rah2464 Member Posts: 1,192

    Raising my hand here as well, developed full blown osteoporosis while premenopausal on Tamoxifen. I think should be standard to have yearly DEXA scans for eval. Please make sure you are getting your weight bearing exercise (ie walking is best) and 1200 mg calcium a day. Make sure you count elemental calcium. So if a tums lists 1000 mg calcium carbonate, the elemental amount may be around 400 mg. It can get a little tricky to keep track.

  • Skwashie
    Skwashie Member Posts: 8

    At first I did not notice any SE as I thought it was post surgery and radiotherapy recovery. So, it was not until a year in that I realised that Tamoxifen made me exhausted first thing in the morning. Coffee helps me, I finally learnt the point of it.

    Then, I noticed my legs were twitching 24 hours a day. I have this sensation where my legs never feel at rest. And at night … that’s when all hell breaks loose. My legs go into full spasms that contort my legs and are painful. This has started to travel up my body and I can wake in the middle of the night with my legs arms hands twisted, taught, in pain. It gets progressively worse the longer I take Tamoxifen.

    the more tired or stressed I am the worse the twitching, cramps and pain are.

    And the bone pain …

    I take it at night, I have always exercised a lot, I have a strict whole food diet.

  • prahan
    prahan Member Posts: 58
    edited April 2023

    Tolerated 4 years of tamoxifen.

    Now fatigue, migrane , dizziness.

    Thinking of quitting or taking lower dose instead of 20 mg

  • balancedco
    balancedco Member Posts: 3

    I had a right mastectomy in Feb. Invasive DCIS. I tried Letrozole but I had severe bone pain and switched to Tamoxifen. I was on it for a month and started getting horrible leg cramps 3-4X every night. The doctor wants me to go on Gabapentin to help with the leg cramps. She said all the other meds have worse side effects than Tamoxifen. Since I have invasive cancer, the Tamoxifen dose can't be lowered so I have to stay on 20 mg. Now I have to decide to stay off Tamoxifen and take my chances of cancer returning or trying it with Gabapentin.

  • moderators
    moderators Posts: 7,685

    Hi @balancedco, and again, welcome to! We're sorry for the side effects you're suffering. We're sure some of our community members will be around soon to share their insight and advice with you; in the meantime, you might find this other discussion helpful: Bottle o Tamoxifen. There you'll find a lot of information and personal stories regarding this drug. Feel free to add yours too!

    Hope this helps!

    The Mods

  • bjohenning
    bjohenning Member Posts: 3

    So, I have been on tamoxifen for about 13 weeks and have had a range of side effects; some were initially bad (brain fog) but have gotten more manageable but not gone completely. I have had intestinal issues, headaches, vision issues, leg cramps and joint aches, as well as hot flashes and now emotional issues. No one item so bad as I can't function, but all together they have me out of sorts. I am not as in control of myself as I normally would be. Oh, and the fatigue. Worse at some times then others, but it doesn't go away. My first re-check with the oncologist is in a couple of weeks and I plan on discussing at length. Five years of this?

  • moderators
    moderators Posts: 7,685

    Hi @bjohenning, and sorry to hear that you're experiencing side effects from tamoxifen. We can only imagine how tough that must be. We wanted to share with you some articles from our main site that could be helpful in dealing with these issues:

    A reference list of side effects and ways to manage them.

    How and What to Eat When You Have Treatment-Related Side Effects

    How long to take tamoxifen and what to expect during treatment

    Hope this helps! And please, let us know how it goes at your doctor's appointment in two weeks!

    The Mods

  • gardengurl
    gardengurl Member Posts: 23
    edited September 2023

    Hi @Bjohenning, Im 63 diagnosed in 3/22. Exact same grade,type, size and initial treatment as you. I started off with the aromatase inhibitors and went off all three after a myriad of side effects. Hot flashes unbearable, despite gabapentin, lexapro. Ive spent so much money on acupuncture and physical therapy without any relief. Currently on a break from tamoxifen after being on for five months. I feel so well right now. No insomnia, no leg pains, hot flashes no brain fog. Ive decided to take a low-dose of tamoxifen when I resume therapy. My onc won’t be in agreement, I know there are no studies that proves it works for invasive cancer, but in theory, it’s better than nothing. There are very few studies done on tubular because it’s fairly uncommon. I wish there was more. Wishing you best of luck going forward.

  • rnjen
    rnjen Member Posts: 13

    Started taking Tamoxifen at age 44. Been on it now for 11 months. When starting about 2 weeks in I had heartburn really bad but it went away after a couple weeks. Also mild nausea which also went away after a couple weeks. The side effects that have been consistent are pretty bad fatigue. I take it in the evening because I tried morning and I was too exhausted during the day. I have pretty significant aching in my thighs/ back/ legs and at night I have really bad " restless legs " ( it is a bad electric feeling in my legs). I also have hot flashes and night sweats. The worst of it was what it did to my uterus. I had no period for 8 months and suddenly had such excessive bleeding that I ended up in the hospital a couple times because my blood counts dropped really low. I had a DNC because my uterine lining was 24mm which they say was caused by the Tamoxifen and now I just had a hysterectomy a week ago. Honestly I am pretty depressed thinking about having this fatigue and pain for the next 4 years. I just try to just deal with it but I don't feel like myself anymore. My job has me on my feet 13 hours a day so it is tough. I want to keep taking it to prevent any future cancer recurrence so I continue to pop my pill every evening and hope for the best.

  • jessanne81
    jessanne81 Member Posts: 1

    I’m 42 and I was diagnosed a few weeks ago. Started the Tamoxifen about 2 weeks ago and so far extreme nausea at times, fatigue and dizziness. I had a hysterectomy in 2015 so no menstrual issues.

  • moderators
    moderators Posts: 7,685

    Welcome to our community, @jessanne81! We're so sorry you find yourself here, but we're glad you've joined us and hope this community can be a source of support for you as you continue down this road. And we hope the side effects get better soon!

    The Mods