Nervous about switch from Letrozole to Exemestane
Hi - I have been on Letrozole for 2 years (invasive ductal carcinoma, node positive, did chemo and radiation, double mastectomy and oophorectomy...was diagnosed right after my 46th bday). Recently I've had neuropathy for the first time (it moves around/switches which limbs it affects...strangest thing). Ruled out metastasis and oncologist said to try a "drug holiday" to see if the letrozole could be causing it. The numbness is somewhat better after a week off the letrozole (but not gone). He suggested I could switch to Exemestane to see if it solves the problem but I am nervous to make the change -- sort of feels like the devil you know is better than the devil you don't? My question is -- has anyone had a bad experience with Exemestane (beyond the obvious hot flashes/joint pain as I'm used to those?). I'm specifically nervous about the "mild androgenic effects" that it can have. I have lost my breasts and just finally grew my hair back out -- I don't want anything to make me feel any less feminine than I already do at times. Also - has anyone else had late onset neuropathy from letrozole? Thanks for anything you can share!
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Hi @blair01, and welcome to our Breastcancer.org community!
We're so very sorry for the reasons that bring you here, but so glad you've found us. You're sure to find our community a wonderful source of advice, information, encouragement, and support — we're all here for you!
While you wait for others to weigh in with their experiences with letrozole and switching AIs, we wanted to share this thread with you to get some insight on what you might expect on exemestane:
Additionally, have you given thought to or asked your doctor about the possibility of going back to letrozole if the effects of Aromasin/exemestane are too difficult? Also, you could talk about trying anastrozole/Arimidex. Here's some more info on the aromatase inhibitors and what to expect:
Aromatase Inhibitors: Benefits, Side Effects, and More
We hope this helps! Please let us know what else we can help with while you wait for others to chime in!
—The Mods
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Thank you so much for your thoughts! I really appreciate it.
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Hi there. I was switched from Anastrazole to exemestene. 3 weeks in i had my yearly physical with my PCP. He did the usual labs. My liver enzymes were off the chart. He was concerned. He contacted my MO who said its unusual so assumed I must be fighting something. PCP said its a sude effect. Anyway long story short they took me off exemestene for a week retested liver and it was normal again. Back on anastrazole with the SE. My MO still refuses to accept the results of exemestene saying its extremely rare. Since then I have heard of other women experiencing liver issues 1 of which was a close failure and yet none of this is being reported. I understand that feeling of switching. You can always go back to the old one if the new one isn't working.
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Hi blair1
I had a similar diagnosis as you, diagnosed at 47, also node positive, had oopho etc.
I switched from Anastrozole (which I understand works similar to Letrozole) to Exemestane like a year ago, 5 years after I started hormone treatment. This was to try and alleviate arthritic pains. The pains are the same (not worse), and I didn’t get any new side effects.
Totally unscientific reasoning here but I would say: if your neuropathy is a freak side effect of anastrozole, if they move you to a drug with a different mechanism, I would say you shouldn’t expect the same freak side effect. Could you now get some different, freak side effect from exemestane? Of course, in cancer land anything is possible, but that would be rare, wouldn’t it? I think you have grounds to be cautiously optimistic here although of course I understand being uneasy.Best of luck,
LaughingGull
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blair1,
I’ve been in a very similar situation, though I didn’t have chemo, even though I was node-positive. I went through all the other treatments, and during the first 2.5 years on letrozole, the side effects kept getting worse. The pain became so intense that at one point I could barely put my feet on the ground—and I’m usually very athletic.
My medical oncologist suggested taking a 6-week break and then switching to exemestane, since it works differently than letrozole or anastrozole. The difference was significant. After about five months on exemestane, most of the letrozole-related side effects disappeared.
I won’t say exemestane was a walk in the park, but it was much more manageable than letrozole. I ended up staying on exemestane for another 2.5 years. Since January 2025, I’ve been off all medications. I do feel better—definitely improved—but not quite 100%. I suppose I’m learning to live with a few lingering side effects.
If I were in your shoes, I would definitely consider giving exemestane a try. Everyone reacts differently, but it really made a difference for me.
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@snoglo27 - Hi, and welcome to the community!
Thank you so much for jumping in and sharing your experience. It’s really helpful, especially for those who are weighing similar decisions.
We're so glad you've joined us, and hope you’ll continue to post and connect with others. If you ever need help finding information or navigating the forums, feel free to reach out. We're here for you!
The Mods
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I am just getting ready to pick up my exemestane prescription from the pharmacy. I have been on anastrozole for a year and the side effects are getting increasingly worse. I do realize that the joint aches will probably continue, as both drugs are AIs, but hopefully the all-over yucky feelings will taper down.
My neighbor was on anastrozole for 2 1/2 years and switched to exemestane 6 months ago She told me she feels so much better. I am hoping I feel better as well and it doesn't mess up my labs. My labs have been great!
Thanks for the discussion everyone!
Hugs, Pam 💗
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I just switched from one year on letrozole to exemestane b/c of tendinitis like everywhere. we did a two week break from letrozole, i seemed to improve, now i'm a couple weeks in with exemstane and i'm actually feeling physically a lot better. I was afraid to switch too for the same reason, am i opening up to another side effect? Sure am. But i figured I could always switch back. It all sucks…but i did chemo and have implants and those were leaps of faith too. Good luck! I hope the switch is ok for you.
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Well, I have now been on exemestane for 4 days. Don’t feel much better yet, but I read that with Anastrozole’s 48 hour halftime, that can take 10-12 days to clear one’s system. I am hopeful that I feel much better in another week!
Hugs, Pam 💗
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I’ve been experiencing trigger finger for the last 2 years and am switching to exemstane (from anastrozole) in 10 days. I’ve already had one trigger finger release surgery and am currently in OT for trigger finger in right middle and left thumb. I’ve also developed Dupuytren in right ring finger. I go back to the oncologist in 4 months to see if my symptoms improve. Otherwise, I’ll go on tamoxifen.
I’m glad to find this thread.0 -
I’m so glad to find this thread! I have been on letrozole for over 2 years now and the joint pain, fatigue, bladder leaks, and trigger finger are getting worse. I took a drug vacation for my 3 week actual vacation and was feeling much improved. I even stopped worrying about having extra bladder pads in my purse.
Now back in the US and back on letrozole for just short of 3 weeks, all the side effects are back. So what are the side effects of exemestane for the former letrozole ladies? How long did it take before you knew what side effects you were getting?
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Hi, all! I recently switched from anastrozole to exemestane about 10 days ago. Very difficult to tell if some of the side effects I’m having now are from one or the other or a combo. I didn’t take any time off between switching. I think, overall, I feel a bit better on exemestane. However, it can take two weeks or more for side effects to diminish. I’ll have to wait and see. It almost seems like I’m having more fatigue. However, that could be due in part to my radiation treatment three months ago which can take some time to totally dissipate.
I feel like I’m constantly doing detective work with very few results. Hope you’re all having a great day.Hugs, Pam 💗
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Today is my first day on Aromasin/Exemestane I switched from Anastrozole. I started Anastrozole in Feb 2025. Lots of side effects, hair loss, fatigue, join pain, just to name a few. I took a 2 week holiday and felt better. Restarted Anastrozole and the side effects came back. Switched to Aromasin today. Cautiously optomistic se's will not be as bad on Aromasin.
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great discussions. I’m having a heck of a time with Letrozole and only 6 months on it. Symptoms are getting worse and not manageable. I see my med onc Aug 20 and will see about switching.
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I have now been on exemestane for about three weeks after switching from Anastrozole, which was giving me not just achy joints, but a feeling of bluckiness. Just yesterday, I finally felt so much better. Could it be that switch? Hard to know. But overall, I’m feeling a lot better and I have much more energy. Hope the same switch helps others.
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Kind of annoyed with my MO’s PA. She responded to my request to discuss switching AI’s with, and I quote, “I will check with Dr (name deleted for privacy) but all AI has the same side effects”.
I’ll overlook the grammatical errors, but that level of dismissiveness doesn’t cut it with me. She is new to the practice and I’m not impressed. I haven’t decided how to respond, but I think my MO needs to be aware of the exchange.
How would you respond?0 -
@kathrynw1thasea Your situation seems a little tricky, but remember, this is your journey. My MO understands that and gives me options and respects my choices.
If you’re thinking of switching from anastrozole or letrozole to exemestane, I would point out that you have a number of friends who have done so and felt much better, and you understand that you may not, but you would like to give it a try. If it doesn’t work, you can always go back on the other AI. I have now been on exemestane just over three weeks. I feel immensely better. I don’t know if it’s just a coincidence or not, but I’m going to continue on it and see how I do. If, after several months, I start to feel the same as I did on Anastrozole, it might make sense to go back on that because it’s less expensive.
Try being polite and calm, (not always easy, I know), and state your position. Ultimately, it is your decision. Good luck with everything! Let us know what you find out.
Hugs, Pam 💗
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I just s-ent the morning in the ER with excruciating pain that they think is sciatica. The meds they gave me helped for a while but I’m at pain level 10 again. Anyone else have this experience?
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sorry to hear you ended up in ER. I haven’t had sciatic pain. But get excruciating joint paint. Yesterday it was my right big toe and knee. Ugh.
Today my ribs are very mad but that could be from all the hack, hack, hacking I’m still having. Currently icing my ribs. They are responding nicely to nature’s pain reliever.The countdown is on to get off Letrozole 9 days to go.
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@canarycat, first let me say that chicken made me smile so hard! Long story short, my annual quilting retreat is at a location with chickens, Nigerian goats, an herding dog, and the cutest little cat. Two of the ladies in the group have chickens and we love it when they sit on the window sill and “talk” with us. Feeding them and watching them get herded back to the coup at night is so fun.
Please let me know how your switch goes. I’m rooting for you. After the doctor told me that the letrozole could be the cause, I am more determined than ever to explore other AIs. I know from my drug vacation that I can feel better off the AIs, but I don’t want to stop treatment. I want to know that I utilized every option to prevent recurrence.
Thanks for your response and keep us posted.0 -
well I’m on a two week drug holiday. MO wants to try me on anastrozole. Fingers crossed it’s better than Letrozole! She also ordered a CT for my right lung and rib issues. Yay. I’ll keep you posted how that goes.
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Just finished my two week vacation from Letrozole. Side effects just kept getting worse. (Been on since April 2025). Today is the end of my "holiday" and start Anastrozole tonight. Fingers crossed that this will be an easier med to live with, since I've got 4.5 years to go on it!
Does anyone have any thoughts on time of day to take it? Mornings vs evenings?
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I’ve been on exemestane for almost a month now. I had some lower back pain before starting the medication and have been doing physical therapy to help with it. Unfortunately, the pain has increased—hard to say whether it’s the drug or just the uptick in activity.
I’ve also been dealing with constipation and hot flashes, which I understand can be common side effects. My trigger finger hasn’t improved, but at least it hasn’t gotten worse.
Hope everyone is doing well.
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@rothmam62 hello. I’m on my Letrozole holiday and will be starting anastrozole around Sept 7. I plan to take it at bedtime as I know I won’t be consistent if I take it in the morning. Fingers crossed we have a good go with anastrozole.
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@canarycat Thank you for your response. I plan to take it a bedtime to start too, just hoping it doesn't keep me awake. I will check back in in a couple of weeks. Fingers crossed for both of us!
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2 year ago I had to switch from letrozole due to significant impact on my mental health. Was off for 1 month & then started anastrozole and did not have same side effects. They do cause different side effects for different people.
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I am told by my MO that switching from one AI to another requires a 6-week break in between to be purged from the body. Also, once you start a new one, it takes about 6 months to really see the SE. One month is not enough.
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@lillyishere going from Letrozole to anastrozole only needs two weeks. It’s the exemestane that would need a longer washout.
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In theory, I understand the need for a purge cycle when switching from one AI to another in order to be certain from a “clean” system that the side effects are different or identical. However, given the need to control hormone levels for effective prevention, couldn’t one also make an immediate switch with the understanding that there will be a “corrupted” blood chemistry for an extended period of time before an accurate assessment can be made?
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My oncologist had me wait 20 days when I switched from Anastrozole to Exemestane.
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