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Letrozole later onset side effects

Posted by louisewalters @louisewalters, Mar 28 6:55pm

I had chemo, surgery and radiation for HER2 stage 2 breast cancer. In March 2024 I was placed in anastrazole, and taken off it in May 2025 due to side effects which I now can’t completely remember. In July 2025 I was then placed on Letrozole and am still taking it. I have suffered from most of the side effects others mention including dry eyes, tendon issues in my wrist, exhaustion, mood changes, a very sore shoulder, etc. I was managing all of this ok, but last week I developed a severe pain in my lower back and it has not gone away. It hurts so much to stand up from sitting, bend over to tie my shoes, pet the dogs, etc. I would like to know if anyone else has experienced this as a late onset side effects others mention and if so, what did you do? I see my oncologist April 8 and would like to provide her with suggestions. Thank you!

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kensiejames | @kensiejames | 6 days ago
In reply to @reflector75 "I’m interested in the occurrence of late side effects. I have seen in the literature that..." + (show)
Profile picture for reflector75 @reflector75

I’m interested in the occurrence of late side effects. I have seen in the literature that this does occur. I have been taking Anastrozole for two years and didn’t develop significant side effects until about three months after starting treatment. I had hoped my side effects had ‘ peaked’ but still struggled on with them. After eighteen months I suddenly began to develop quite severe hand symptoms, which I thought those who experience them usually get fairly early on in therapy. It seems that these drugs are ‘ the gift that keeps on giving’ and. I am just hoping no more ‘ surprises’ pop out of the cupboard!

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@reflector75
Hey there!
In 2006 I was diagnosed with breast cancer. I went through surgery,chemo, radiation, then 2 years of Tamoxifen and 5 years of Femara. The Femara hits hard. As the years went by the pain got worse, sucking the life out of me.
Fast forward to 2012, I developed Rheumatoid Arthritis. I believe this was a direct result of the Femara.
All these drugs have the potential to cause long term issues.
Listen to your body, do your own research on the benefits vs risk of taking these drugs . Discuss stats with your doctor .
All the best 🙏🏻

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prarysky | @prarysky | 6 days ago
In reply to @pat9892 "If you are taking calcium & D supplements a 24hr urine test can let your doctor..." + (show)
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If you are taking calcium & D supplements a 24hr urine test can let your doctor know if your body is actually absorbing the vitamins/minerals you are taking. I didn't know that until I saw an endocrinologist. All the lab work I've had and she was the only one who had me do that test. Maybe sciatica? Back issues hurt!

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@pat9892 Do you know the name of the 24 hour urine test? Thank you!

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prarysky | @prarysky | 6 days ago
In reply to @kensiejames "@reflector75 Hey there! In 2006 I was diagnosed with breast cancer. I went through surgery,chemo, radiation,..." + (show)
Profile picture for kensiejames @kensiejames

@reflector75
Hey there!
In 2006 I was diagnosed with breast cancer. I went through surgery,chemo, radiation, then 2 years of Tamoxifen and 5 years of Femara. The Femara hits hard. As the years went by the pain got worse, sucking the life out of me.
Fast forward to 2012, I developed Rheumatoid Arthritis. I believe this was a direct result of the Femara.
All these drugs have the potential to cause long term issues.
Listen to your body, do your own research on the benefits vs risk of taking these drugs . Discuss stats with your doctor .
All the best 🙏🏻

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@kensiejames I started letrozole in July 2025 and have noticed the common side effect of more joint pain. Last week, my left knee buckled and gave out and I couldn't put any weight on it. This could have been related to an old knee issue from decades ago, but it's largely been under control. A few days ago, the preexisting arthritis in my neck set me up for a neck spasm simply lifting the cord of a window shade.

These things could have been happened independently of the letrozole, but doubt it. I had no idea that long term use of letrozole was associated with a high risk of rheumatoid arthritis. Will ask my oncologist about this. A potential side effect that was not directly mentioned by my oncologist or PA.
Here's to your health!

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louisewalters | @louisewalters | 6 days ago
In reply to @charlesgreenberg "@louisewalters Seems there are many who have problems with anastrozole. How frequent is this really? This..." + (show)
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@louisewalters
Seems there are many who have problems with anastrozole. How frequent is this really? This site is a magnet. Well, I did too, on Anastrozole. Bad leg pain just walking around with moderately elevated AST, ALT, LDH. Onco said maybe Hepatitis, and need a PET scan. Stopped Anastrozole after 3.5 months and no pain in 4 days. Labs normal in 3 weeks. Hep tests normal. I have been vaccinated against A & B. No PET.

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@charlesgreenberg Thank you for this. Good to know symptoms let up.

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charlesgreenberg | @charlesgreenberg | 5 days ago
In reply to @louisewalters "@charlesgreenberg Thank you for this. Good to know symptoms let up." + (show)
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@charlesgreenberg Thank you for this. Good to know symptoms let up.

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@louisewalters
Thanks for your input and good wishes.
What is likely to be the replacement for Anastrozole?
Is anyone taking 50mg of Verzenio twice a day?
Thanks.

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louisewalters | @louisewalters | 5 days ago

I take Letrozole and so far, no replacement has been discussed. Will be discussing with onc.
I am not familiar with Verzenio.

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pat9892 | @pat9892 | 4 days ago
In reply to @prarysky "@pat9892 Do you know the name of the 24 hour urine test? Thank you!" + (show)
Profile picture for prarysky @prarysky

@pat9892 Do you know the name of the 24 hour urine test? Thank you!

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@prarysky My endocrinologist referred to it as a 24 hour urine collection. I am supposedly taking Risedronate to strengthen bones while I am on Letrozole (until 10/2030). I don’t like taking it because of the side effects. But I don’t really like taking any medication that I don’t need. I’m glad this is going to be monitored by my Endocrinologist but I will be monitoring it too also my dentist since jaw necrology is a possible side effect. I have been taking risedronate for less than one month so far it’s been OK for me.

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charlesgreenberg | @charlesgreenberg | 4 days ago
In reply to @louisewalters "I take Letrozole and so far, no replacement has been discussed. Will be discussing with onc...." + (show)
Profile picture for louisewalters @louisewalters

I take Letrozole and so far, no replacement has been discussed. Will be discussing with onc.
I am not familiar with Verzenio.

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@louisewalters
Verzenio is generic Abemaciclib, by Lilly, quite expensive. I took 300 mg/day for 1 month and had to discontinue because of severe weakness and major walking instability. Now taking 100mg/day without difficulty. I am not sure that that dose is much effective.

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prarysky | @prarysky | 4 days ago
In reply to @pat9892 "@prarysky My endocrinologist referred to it as a 24 hour urine collection. I am supposedly taking..." + (show)
Profile picture for pat9892 @pat9892

@prarysky My endocrinologist referred to it as a 24 hour urine collection. I am supposedly taking Risedronate to strengthen bones while I am on Letrozole (until 10/2030). I don’t like taking it because of the side effects. But I don’t really like taking any medication that I don’t need. I’m glad this is going to be monitored by my Endocrinologist but I will be monitoring it too also my dentist since jaw necrology is a possible side effect. I have been taking risedronate for less than one month so far it’s been OK for me.

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@pat9892 Thank you for replying with more info. I think it's a positive sign that your endocrinologist has ordered the 24 hour urine collection. It sounds like it's a wise step for more doctors to take in evaluating their patients. For anyone else interested this is some information I found describing the test further:
https://www.labtestsguide.com/24-hour-urine-sample
Best of health going forward!

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louisewalters | @louisewalters | 4 days ago
In reply to @pat9892 "@prarysky My endocrinologist referred to it as a 24 hour urine collection. I am supposedly taking..." + (show)
Profile picture for pat9892 @pat9892

@prarysky My endocrinologist referred to it as a 24 hour urine collection. I am supposedly taking Risedronate to strengthen bones while I am on Letrozole (until 10/2030). I don’t like taking it because of the side effects. But I don’t really like taking any medication that I don’t need. I’m glad this is going to be monitored by my Endocrinologist but I will be monitoring it too also my dentist since jaw necrology is a possible side effect. I have been taking risedronate for less than one month so far it’s been OK for me.

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@pat9892 The onc gives me zoledronic acid aka Zometa for bone strength. It’s an infusion every three months for two years.

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