Tamoxifen and Fibromyalgia

I started on Letrozole, which crippled me after two months, then was put on Exemestane, which almost finished me, took a 3-month break with little improvement. I have been on Tamoxifen for 4 months now, and my fibro is through the roof. I have pain in all my joints and bones, muscles and tendons. Life has become hard with just crumbs of joy now and then when I take more anti-inflammatory drugs than prescribed. Both my oncologist and my GP tell me that Tamoxifen shouldn't give me such painful symptoms. They have no idea how it affects fibro, which is depressing. Don't know where to turn. Before the mastectomy, my oncologist asked my rheumatologist to check I was fit for such a big surgery in September 2024, so she did all the usual tests, checking markers, etc., and they were all low. I had been seeing her for joint pain 10 years earlier, so she was still in my medical records. Fast-forward to February 2026, and I had such unbearable pain in my spine that my oncologist ordered a full-body bone scan, worried the cancer had spread to my bones. Luckily, there were no tumours detected; however, it showed arthritis in most of my joints and lower and upper spine and neck, shoulders, elbows, wrists, thumbs, clavicles, hips, and toes. My oncologist said 'you've got a bit of arthritic uptake in the back, shoulder and wrist but offered no solution other than to stay on Tamoxifen to reduce my chances of the cancer coming back. My GP offered no solution either. I asked her for a referral to my rheumatologist and to an osteopath, as in addition, I have spontaneous fractures to three vertebrae and a slight scoliosis. I am being proactive, trying to find solutions, as my life otherwise, as it is, with all the pain and not being able to have a social life or work, barely able to look after my home and my pets, is not worth it. My doctors, on the other hand, are lame, lazy, not interested, and just want to move on to the next patient. It's going to be hard paying for the specialist's appointments, but I don't know what else to do. Just typing this long message will leave me in pain from my shoulders to my fingers and hips from sitting in one position for a relatively short time. Has anyone had a similar situation where blood tests come back clear of arthritis markers, then just a few months later, they are riddled with arthritis? I knew for a long time about my fibro. Are the hormone blockers to blame? It seems that way, but why do doctors play it down?

Hi, I'm on this road right now and I am so miserable! I have tried just about everything! NOTHING HELPS and Dr's and nurses DON'T understand or "get it!"
I'm in bed crying and searching for anything that will help!
Cannabis does help a little but it's expensive!
The pain and aches and spasms and and and... I just sent a note to my Dr that I need a break from the Letrozole but I know I really shouldn't. HELP!

Hi, I'm in the same position. I'm worried at the idea of 10yrs on Tamoxifen.
I've had Fibro ,CFS & and migraines for over 25yrs which was helped by HRT. All pre my cancer & treatments.
All HRT was stopped immediately I was diagonosed with Invasive Ductal Cancer (IDC) & was given Tamoxifen as you say keep growth & recurrence at bay. But the downside of Tamoxefen is horrid my quality of life is worsening with increased muscke & joint pain, fatigue & Migraines.
Pre my cancer at menopause I had HRT and as you say the Estrogen was a total GAME CHANGET improving my Fibro joint pain, fatigue. It was noted also my bone density improved & my dexa scans became normal again.
I'm now very worried about long term Tamoxifen.
Are there any reports, trails etc on the affects on Fibro, fatigue, joint pain & Migraines.. etc
Likewise I'd like to hear from others with Fibromyalgia, Me & CFS to see how they are on Tamoxifen.
I'm finding every day a challenge not because of cancer etc...but because of the awful pain & fatigue I'm positive it's worsening with daliy Tamoxifen. But I've no options med wise as the other medications badly affect my bone density so are a no no...!!

Hi, I'm in the same position. I'm worried at the idea of 10yrs on Tamoxifen.
I've had Fibro ,CFS & and migraines for over 25yrs which was helped by HRT. All pre my cancer & treatments.
All HRT was stopped immediately I was diagonosed with Invasive Ductal Cancer (IDC) & was given Tamoxifen as you say keep growth & recurrence at bay. But the downside of Tamoxefen is horrid my quality of life is worsening with increased muscke & joint pain, fatigue & Migraines.
Pre my cancer at menopause I had HRT and as you say the Estrogen was a total GAME CHANGET improving my Fibro joint pain, fatigue. It was noted also my bone density improved & my dexa scans became normal again.
I'm now very worried about long term Tamoxifen.
Are there any reports, trails etc on the affects on Fibro, fatigue, joint pain & Migraines.. etc
Likewise I'd like to hear from others with Fibromyalgia, Me & CFS to see how they are on Tamoxifen.
I'm finding every day a challenge not because of cancer etc...but because of the awful pain & fatigue I'm positive it's worsening with daliy Tamoxifen. But I've no options med wise as the other medications badly affect my bone density so are a no no...!!

I have chronic pain with fibro-like symptoms (but it is not an exact diagnosis for me). The pain was indeed worse after surgery and radiation. My PCP doubled my pain meds (I do well on these) and I continue with rolphing/PT/micro current twice a week (yes, out of pocket). About 8 months out from treatment, I'm back to "normal." But I have thoughts for you. Will your oncologist allow a tamoxifen "vacation"? That will give you more information about source of fibro increase. In addition, can you switch to a different estrogen suppressing drug? I'm doing well on letrozole (although yes, many women have bad symptoms). You might also discuss dosage--can yours be lowered without ill effect etc. Also, try and get some actual statistics. If tamoxifen lowers recurrence rate just a little you might see if you really think it is worthwhile. Sorry that this advice is work for you, when you least need it, but it is what came to mind. I do think chronic pain made my recovery harder, but at least I expected I wouldn't be "fine" 3 days after lumpectomy! Wishing you some positive change.

Hi, I'm in the same position. I'm worried at the idea of 10yrs on Tamoxifen.
I've had Fibro ,CFS & and migraines for over 25yrs which was helped by HRT. All pre my cancer & treatments.
All HRT was stopped immediately I was diagonosed with Invasive Ductal Cancer (IDC) & was given Tamoxifen as you say keep growth & recurrence at bay. But the downside of Tamoxefen is horrid my quality of life is worsening with increased muscke & joint pain, fatigue & Migraines.
Pre my cancer at menopause I had HRT and as you say the Estrogen was a total GAME CHANGET improving my Fibro joint pain, fatigue. It was noted also my bone density improved & my dexa scans became normal again.
I'm now very worried about long term Tamoxifen.
Are there any reports, trails etc on the affects on Fibro, fatigue, joint pain & Migraines.. etc
Likewise I'd like to hear from others with Fibromyalgia, Me & CFS to see how they are on Tamoxifen.
I'm finding every day a challenge not because of cancer etc...but because of the awful pain & fatigue I'm positive it's worsening with daliy Tamoxifen. But I've no options med wise as the other medications badly affect my bone density so are a no no...!!