Anastrozole Brain Fog

Thank you all for your comments. (February was double mastectomy; April-May was radiation of 38 treatments)).I always felt as though I was the smartest person in the room....now I can't seem to get it together. I don't know if it is the Anastrozole...I just know I am not myself. On top of the brain fog, the night sweats, forgetting words, and just feeling weak all the time, I am now getting mouth sores and having belly issues. During menopause (25 years ago), I breezed through it...holding down 2 jobs getting my children through university degrees. Now...I am weak...tried to go to gym for elliptical, walk a mile a day....not happening....just made me feel weaker after 2 weeks. Eating healthier than ever...and I was always a healthy eater...still no relief. I see my cancer doctor on the 10th for treatment of leukemia (WBC less than 2, ANC less than 2, mono% high, RBCs low) and immunity disorders (IGg, IGm) and my radiation cancer doctor a week later....hoping for answers. Maybe a change of med????? or does this get better????

@gailmarienewton I had all the same things on Anastrazole coupled with pain. Chronic low level but with daily episodes of stabbing pain somewhere (today left ankle, tomorrow maybe right hip). After 9 months, moved to exemestane. Pain was better but weakness, elevated hear rate/BP. I have mouth problems but they started during chemo so not sure if damage from that which could be exacerbated by the ai therapy or directly because if it. For me, didn’t get better, just gradually worsened. After 17 months, he gave me a month off and I took 6 weeks because it took a month to feel better. Wanted to retry it and everything started back up. So I’m now on a 2 week reprieve before I start Letrozole and see how that goes. Not optimistic because from what I read, Letrozole is Anastrazole on steroids but we’ll see. Hang in there. We all respond differently so they may try a different one that does better for you. My personal opinion is that there will always be some level of brain fog because of the lack of estrogen so just have to find the one that has least amount.

I had 25 radiation treatments after having a partial mastectomy in March 2026. I am not eligible for Chemotherapy. (I also have myasthenia Gravis and multiple sclerosis). I was given 4 previous drugs to lower my estrogen level and had severe side effects to all. Anastrazole was my final option. It does cause pain in my bones, especially my lower legs and feet. Lately I’ve noticed frequent brain fog. I’m a retired nursing education coordinator and I spent much of my time researching and sharing information.
Since starting Anastrazole I find I’m forgetting simple words, names of old friends, my plants. I recently failed the 3 word memory test during my annual physical with my primary care doctor. I’ve never had a problem remembering 3 simple words. I was embarrassed and shocked. Then decided to see if this could be from the Anastrazole. My regular oncologist is moving to another state and I will be meeting my new one next month. I will ask her what will happen if I stop taking it.
Sadly this week I was also diagnosed with colon cancer. Not sure what my treatment options will be. I also just completed treatment for skin cancer. I’m 81 and all 3 cancers occurred this year. Quality of life is important to me since my husband has Alzheimer’s. So I do need to provide for his needs take care of our young dogs and other routine household needs. Though thankfully my husband does a wonderful job doing our laundry. Any suggestions would be appreciated.

I also had Brest Cancer, it was the year I turned 60, on my birthday I am now turning 80. After the Chemo I had 33 Radiation treatments and then I was prescribed Anastrazole for the test program. Chem fog certainly set in and I became very forgetful, confused and tired. I now have Neuropathy in my right arm top to bottom. The pain is so very severe I can not use my arm or hand to hold anything or my arm for anything. I really wrote to let you know about how long that drug has been used. I am so sorry for your recent diagnosis. It sounds like you have been through an awful lot, you must be very strong. Try to only good thoughts and stay strong! Wish you and your husband WELL 🙏 .

@gailmarienewton
I was also put on Anastrozole after my lumpectomy and took it for quite awhile. I am 5 years out from my surgery and have since been put on a few others. My brain fog is ridiculous! I don't think it is JUST the anastrozole but do believe all the the AI's they put you on cause some sort of brain fog and I've been on a few. I don't think there's much you can do for the side affects of these drugs but learn to live with it. I am somewhat better now, but still have blank moments.

Thank you. I joke that I use to be the smartest person in the room… not anymore. I am trying to build up strength by walking and swimming, but still in a fog. It is difficult. Smiles always.

@elliern, that is a lot to deal with. Should you wish to connect with others as you learn about your treatment plan for colon cancer, see this related group:
- Colorectal Cancer Support Group https://connect.mayoclinic.org/group/colorectal-cancer/

And if interested:
- Multiple Sclerosis (MS) Support Group
https://connect.mayoclinic.org/group/multiple-sclerosis-ms/

I don’t hear of anyone actually stopping The anastrozole I took it for two months could not stand all the pain and weakness I stopped. I haven’t seen my doctor yet to tell her it’s too in September. I don’t plan to start another one. I hope I can Find a professional that will help me with some natural treatments. I’m not having that pain for five years.

@jacquelinejohnso
I was on Exemestane for 5 months with the brain fog, insomnia and very low mood ( not quite depression). I stopped it on my own as I couldn’t tolerate it anymore. I waited 2 weeks to tell my dr. She said it was fine to stop for 4 weeks. My follow up is September 10. I’m not sure I am willing to switch and try another one. I will update here what is advised.

I have been on Anastrozole for 3 years now and experienced brain fog. I have had to make lots of reminder notes for myself every day. It’s frustrating but I am hoping it will go away once I complete the 5-years course.