Letrozole: Anyone have muscle pain as a side effect?

I already had suffered for over 10 years with ME/CFS after battling a very bad second Lyme Infection with multiple coinfections. I fact, I was awarded full disability for both. The ME/CFS got so bad I was ed ridden 80% of my time, and the rest I could only use very restricted activity. The pain was endless. I also had spinal stenosis and a crushed vertebrae after a total car accident. Additionally, I suffered a very severe case of Endometriosis that began round age 13. Because it was unknown then, I got no help until many years later. I still have it, but because I am post-menopausal, no doctor will operate (more and more reliable studies show that this is not the case. Then 3 years ago I got Long COVID = more ME/CFS. I am now battling Inflammatory Breast Cancer, was prescribed Letrazole and zero additional pain medicine! I was told either take the Letrazole or stop it (and die of cacer). Pain management is a joke for acute severe chronic pain. Yoga, certificate acupuncture, massage, etc, may help a little, but I do have the money for any of those things. I never heard of a Cancer Hospital not giving pain meds. Yet I am at my second opinion hospital where it came down to the same mis-treatment. I was laughed at for suggestions, never once given a single choice into my care plan, and was manhandled by an ancient GYN who was rude to boot. Is this how the poor with Medicare get treated now? Or do all patients get mistreated like this?

Oh! God Help Us All!

@godhelpusall: I hear you, I almost feel your pain and ache for you... I am so sorry for all your sufferings through the decades!

As most of us probably have experienced this personally, that just about all medications have side-effects or our bodies' reactions to them... In my case, my main goal is to keep those hormone-fueled cancerous cells from popping out anywhere in my body so I strive on taking AI's medicine and mitigating any pains that come with it along the way. It is not an ideal situation, but this is part of my journey...

Wishing you all a blessed holiday season with peace of mind, joyous gathering with your loved ones, and hope for a healthier and happier New Year!

I have been on Letrozole for 1.5 years. First I got 3 trigger fingers in each hand. Had surgery on my right hand since I'm right handed but chose not to address left hand since I have lymphedema following my left mastectomy. One trigger thumb resolved itself on the left hand but now my right hand/wrist is really painful. If this continues, I'll lose functionality entirely so I stopped 2 weeks ago. Since most of the AIs have similar side effects, looks like I'm going on Tamoxifen. I'm 67 with stage 3 C estrogen receptive cancer.

Dear Karla:

I am so sorry for what you've been through for more than 1.5 years:( I almost feel your pain because I experienced similar aches and pains from taking one of the AIs also...

Have you tried physical therapy/occupational therapy to resolve these painful issues yet? They helped me tremendously! Here is my story... I started taking Anastrozole on 1/18/24; experienced loads of awful side effects such as: joint pain, trigger fingers, muscle pain all over my body, back pain, etc., almost immediately after taking this AI medicine. Apparently my old body still needs hormones to function adequately! Due to the fact that I declined the radiation treatments against my oncologists' recommendation already, I decided to continue taking Anastrozole - like you said, all AIs have similar side-effects, my cancerous cells are ER95%+, PR+, and Her2-, and taking any AIs is the only avenue for me to keep those hormone-fueled cancerous cells from popping up anywhere in my body:(. Toward the end of February, I developed an acute Lumbar spine issue, MRI showed troublesome issues along my Lumbar Spine, and my medical Oncologist referred me to a Spinal surgeon! I turned to my primary care physician for help, because the thought of spinal surgery sent chills to my bone:( Fortunately for me, my kind-hearted PCP recommended PT/OT for cancer patients' rehab for me to strengthen my weakened back, muscles, bones, & aching joints and gradually keep my fingers moving daily. The aches and pains are still there with much less intensity, but at least I can perform my daily functions normally.

Sorry for such a lengthy note, but I simply wish to share with you my personal struggling experiences to show there's hope to mitigate pain under any circumstances. Please bring up all your side-effects and discuss with your physicians - especially your PCP - to see if they'd recommend any viable solutions for you.

Best wishes to you all for the new year!

@windyshores I did almost 2 weeks off letrozole and no migraines and no other bone pains. It was great. I went on Anastrazole right after Mother’s Day and I initially felt so good with no pain in my legs and very comfortable. 7 days later, I was in the hospital for two days for really strong pain from my gut to my side to my shoulder and my back. It felt like knives. I was treated and the pain subsided on the third day. I picked myself up and moved forward heating my back every day to keep the pain calm. Two weeks later, my back had the pain again right in the middle of my Mahjong game, I could no longer sit upright, so I went home and called my doctor. I was back at the ED. They gave me an IV with the pain medicine and it went away. 8 1/2 hours. They have recommended coming off the Anastrazole, which I had so many hopes for. It is my birthday this weekend. ED recommended not taking the medication so I have to stop until I see my oncologist. It has been almost a year. I have lost a lot of bone; my back has a lot of issues, I have worked hard to get comfortable, but one step forward and many steps back. They had noted it as muscle pain but it is muscle and bone. I have had arthritis for years and finally felt it was in control. Now, I would like to stop the medications because it is hard to sit up, walk, We have a three weeks vacation in August. What would you do?

@lifetraveler I wrote a note in a post below. Same thing snd had been doing great on PT but have gone backwards and the pain in my back stopped me from doing my daily social/community activities. Please read my post from Lkng; I am at a milestone.

I did do radiation and double MX.

Hi! @lkng67 :

I am so sorry for all you've been through, Lkng:( Journey of fighting the disease of cancer truly is a bumpy road, isn't it?

I am not any medical expert, but please get your pain evaluated before deciding it is truly from taking Anastrozole. Please allow me to use my own personal experience to explain why. As I stated before: I have been taking Anastrozole since 1/18/24, and have been utilizing a PT/OT rehab program for cancer patients to mitigate any aches & pain due to the lack of estrogen hormone production in my body. As it happens, I've been experiencing this unrelenting pain ever since 12/19 of last year myself. It started with a sudden deep bone pain in my left hip, saw the internal medicine physician on 12/23 and was given some prescription muscle relaxer; unfortunately it turned worse and started its downward spiral. Finally had an MRI done on 12/31/25 for the spine and hip, and it revealed that there's a 1.4 cm cyst pushes to the left side of my Lumbar spine at the Nerve Root Base that sends the radiating pain through my left hip towards the entire left leg, ankle and the toes thus causing the challenge in walking and all pain. I saw an orthopedic spinal surgeon on 1/29/26 and discussed several treatment options with him; I decided to take oral steroid medication (for 10 days) to calm the urgent inflammation first, and proceed with physical therapy sessions to strengthen my muscle to support the back, spine & all. I am so sorry for my lengthy note; but I am striving forward with whatever strength that I can gather. I am still going for PT sessions twice a week - without any pain medication - right now; even though the numbing pain still exists in my left lower leg and ankle, but with much less intensity and I can walk "normally" and proceed with daily functions as normal as I can, and went back to serve at soup kitchen voluntarily since March, and I am still taking Anastrozole to prevent any future recurrence or metastatic of cancer.

So please have your pain evaluated by a medical specialist to find out the essential cause of your pain. Perhaps ask for an MRI to find a more detailed assessment. You'll be in my thoughts and prayers, Lkng; for I consider you as one of my comrades.

Wishing you all a better journey ahead with hope, love, and peace!

Thank you so very much. I am also at physical therapy twice a week and until Anastrazole have progressed significantly (except for the headache migraines on Letrozole).

The sudden additional back pain, which I have had a little of before, has been assessed in the emergency department at Mayo three times with multiple scans and I have some cysts in a few areas but not on my spine. I do have hemangiomas on the spine. They singled that out for me as a CT on Friday. I have had so many scans over the months I cannot count them all.

I have been a patient on 4C at Neurology after a mini stroke that impacted my right hand for a short while. They took care of me wonderfully. They also scanned my brain for the headaches. I don’t have them when off the pills. The dental doctors believe this may be TMJ and the pills go after its weakness.

I have also been in observation after my surgery in the fall of last year for my enzymes being very “off” as a left over from the surgery anesthesia they believe. This resolved over time, but was disturbing.

I have good physical therapy twice a week but the first Anastrazole attack of pain was so bad that I now have repetitive pain in my back; so hard to handle. I was in the ED last Friday. My spine has lost a lot of bone and I have lost 2 1/2 inches and have more chronic issues in my back from top to bottom. The results were detailed. I also have rib issues which are on my left side where I had a hernia after a cancer removal 20 years ago (DFSP). I think the mesh from the hernia is now clearly embedded in my tissue and when I eat, it hurts the rib cage. I have areas of the lung that have depleted due to this but my lung capacity is still good. The ribs always hurt since 2000 but I was able to get shots for it and, now the pills have taken their toll, the pain has started again.

I have done a lot of research and can only go so far. I have been off the pills twice for short periods and the loss/reduction in headaches is palpable and so is the bone pain.

I will be talking to my oncologist next week and discussing next steps. I talked with my daughter and she and I both agree that if this cannot be resolved then I have to make a decision that will give me quality for whatever time I have left in my life, hoping for a lot more. I turn 71 years tomorrow and, all Signatera tests have been negative so far. I am was a 1C, but a 1A initially. I had one node impacted. I want to continue to travel and enjoy this planet. I don’t want to be curled up with a heating pad every day, and visiting the hospital so often.

I so appreciate you. I agree that I need and want some peace in this tough medical and political time and to enjoy my family of whom some are in other countries.

Thank you. Please keep in touch I am in the group sessions now at Mayo online.

Best to you. Thank you for cheering me on!

@lkng67 :

Wishing you a splendid Birthday filled with joy, love, hope, and peace!