The Dark Side of Aromatase Inhibitors, Part 2

The Dark Side of Aromatase Inhibitors – Part 1

I decided to divide this topic up into a couple of posts because as you may or may not know, I’m working on being less wordy and more concise in my writing. Part one will be my attempt to convey some general information about aromatase inhibitors and part 2 will be more focused on my personal experience – rant, so stay tuned.

February 2019 update:  You might want to read and download, Endocrine Therapy – Managing & Making Decisions About Your Aromatase Inhibitor Medication.

Many breast cancer tumors are estrogen positive (ER-positive), progesterone positive (PR-positive), or both (ER-positive and PR-positive). Mine was both.

By the way, this information about your tumor(s) is provided in your pathology report, and you simply must have a copy of this report in your possession so you can familiarize yourself with your own unique cancer’s biology, even though this might sound like the last thing you want to do after your diagnosis.

Be sure to ask for a copy if you don’t receive one.

If a woman is ER and/or PR positive, her oncologist might very likely prescribe an aromatase inhibitor after surgery, chemotherapy or radiation as part of her adjuvant therapy treatment plan. The intent is, of course, to prevent recurrence.

There are three kinds of aromatase inhibitors (referred to as ‘AIs’ from here on out) that have been FDA approved:  anastrozole (Arimidex®), letrozole (Femera®) and exemestane (Aromasin®).

Basically, these drugs block tumor growth by lowering the body’s natural supply of estrogen.

How do they do this?

These drugs don’t allow the food supply (estrogen) to get to the tumor because they block the aromatase enzyme, which is needed for the production of estrogen.

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Hence the name, aromatase inhibitors.

AIs are often prescribed for post-menopausal women because they don’t block estrogen produced by the ovaries, but do inhibit estrogen production in other body tissues. If you’re not post-menopausal, the benefit’s not there. For pre-menopausal women with estrogen positive cancers, Tamoxifen is still the recommended hormonal adjuvant therapy drug most often prescribed.

Before cancer, I didn’t even know that in addition to the ovaries other body tissues also produce estrogen, but they do.

As I understand it, there isn’t a lot of difference between the three AI drugs. One difference however, is that Aromasin® is an irreversible aromatase inhibitor (stops aromatase enzyme’s production process permanently) while the other two are not.

Studies seem to indicate the effectiveness of the drugs in preventing recurrence is pretty much the same.

AIs have become standard treatment for adjuvant hormonal therapy for many post-menopausal breast cancer patients; gotta shut that estrogen production line down – and that’s what AIs do.

I clearly remember the day when oncologist number one showed Dear Hubby and me all those mind-boggling, ten-year survival odds charts. The charts ‘said’, that if I agreed to add Arimidex® as part of my adjuvant treatment plan, I would supposedly gain another six percentage points for my staying-alive plan.

I was on board. I wanted those additional six percentage points on my side.

Who wouldn’t?

And now on to the dark side of AIs – in case you can’t guess, but I’m betting you probably can, this would be the nasty side effects.

Every person is different. Just because you’ve heard horror stories about unpleasant side effects, don’t assume you’ll experience the same.

Having said this, some of the side effects are fairly common and even somewhat predictable.

Generally speaking and maybe even mildly comforting to know (then again, maybe not), the side effects of all three AIs are similar.

The main and most often complained about side effects are:  joint pain, bone loss, bone fractures, lowered libido, hair loss/thinning, weight gain, hot flashes and sleep issues to name a few. (Yikes, do we really need more?)

The side effects are often not addressed adequately, if at all, by oncologists. This is too bad because side effects can, at the lesser end of the spectrum, be highly annoying and at the worst end, extremely debilitating.

I speak from experience on this as I have had some very unsettling side effects myself.

In fact, side effects (mine anyway) are the focus of The Dark Side of Aromatase Inhibitors – Part 2.

Get your rants ready too!

Note:  Please remember that while I always strive for accuracy in facts I share, my posts also generally include my thoughts and opinions and are not intended to be medical advice specific to you. Please discuss all concerns with your doctor.

Are you on an aromatase inhibitor or do you know someone who is?

Are you on Tamoxifen?

If so, how are things going and are the side effect issues (if you have any) being adequately addressed?

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Update:  You might want to read and download, Endocrine Therapy – Managing & Making Decisions About Your Aromatase Inhibitor Medication.

The dark side of aromatase inhibitors, part 1 #breastcancer #endocrinetherapy
The Dark Side of Aromatase Inhibitors


353 thoughts to “The Dark Side of Aromatase Inhibitors – Part 1”

  1. Do all these breast cancer drugs pretty much have the same side effects? i’m starting exemestane, will my hair thin out eventually?….What other major side effects are caused from this drug?

    1. Teresa, Everyone reacts differently. Having said that, many women do experience similar side effects. You should receive a list of all potential side effects when you receive your medication. Remember, you might do fine. Don’t assume the worst will happen. My advice is to start a journal so you can document changes/side effects if and when they happen. My best to you.

    2. I have recently switched from Letrozole to exemestane about 4 months ago. My SE are significantly less now. I was experiencing bone/ joint pain, hair loss, memory problems, dry itchy skin just to name a few. Now I still have slight memory issues, but much improved. I still get stiff if I sit for any length of time, but I had that on both. I was on Letrozole for 2 years before switching.

  2. I’ve been on Aromasin almost 6 months. In the last 3 weeks my hands started tingling. Now and overnight, my thumbs have almost “locked up” and are popping like in trigger finger. The bones in one foot are also very sore. My hips were achy but have gotten better. I reported this to my oncologist and he “suggested” it may be arthritis and maybe not related to the drug. I told him it came on so suddenly! He took me off the drug for 30 days to see if that makes the joint pain go away. Since my last appointment, I’m having muscle cramps with a muscle spasm in my back–very uncomfortable. I stay on a heating pad! Do you think these symptoms are from the drug? I’m 65 and haven’t had any of these problems before now. I feel like the onco poopooed me off.

    1. I had the same experience. On Letrozole for 4 months with only minor hot flashes (I’m pre-menopausal on ovarian suppression Zoladex in order to take Letrozole.) and hip stiffness/aching that I attributed to over doing it with exercise. At month 4, my hands were stiff at night; when clenched it was very painful to pry them open. Then, at month 5, I had painful trigger finger in my ring fingers and pinkies.

      My surgeon was adamant that AIs do not cause trigger finger. She put me on a 30 day break from Letrozole during which my hips stopped aching. My hand stiffness lessened a tiny bit, but the trigger fingers persist. I demanded to be assigned to an oncologist within the clinic as I knew after surgery my surgeon would be out of the picture and no one would follow me for the AI issues. This offended my surgeon! (As an aside, my surgeon tries to play the role of oncologist, radiation oncologist and radiologist. It’s incredible: I have the latter two different docs but my surgeon argues with them!) I did finally get assigned to a medical oncologist, and he also maintains that Letrozole does not cause trigger finger. He says that the AIs create symptoms that mimic arthritis, but there really is no physical change in the joints. Then where does the stiffness come from, if it is not physical?!? For what it is worth, a Lymphedema physical therapist in my clinic said that the AIs do make joints triggery.

      My feeling is that if you know your body and you have sudden onset of Joint and muscle pain symptoms after taking AIs (even 6 months in), it is entirely plausible that they are due to the AI. The challenge is weighing the huge anti-cancer benefits against the arthritic symptoms. Some enlightened oncologists have studied how to mange the side effects and found acupuncture and exercise (moving the joints to keep them lubricated and flexible) work the best. I just wish that the other oncologists would stop poopooing our concerns and just say, “yes, this happens, but you can try the these things to manage the symptoms”. Just getting validation for our concerns makes such a difference.

      1. My oncologist said that a eyes definitely caused trigger finger, and I have already had two of them, with the most recent one being less than a year. My hands are so sore at night that I can sometimes not sleep. I bought something called arthritis gloves, which helps but my side effects on many many more. I have joint pain, muscle pain, and bone pain, throughout my body. Everything hurts all the time but in different places every day. It keeps me guessing constantly. The fatigue is awful and The hot flashes persist.

      2. I was on ai’s for 5 years. I finally had to have surgery to correct a trigger finger on my dominant hand. The surgeon performing the surgery noted he has an endless line of patients needing the surgical procedure, all of whom took ai’s post chemo and radiation. It’s appalling that oncologists still tell their patients that there is no connection.

      3. The same thing happened to me, I had to take my rings off ,my hands were so painful, went off anastrozole now ,ny oncologist suggested to for a few weeks to see if that was causing the pain in my hands ,thats what im doing now, im hoping for positive results from being off the medication, don’t know what my options will be next ,was already on tamoxifen after radiation, hoping for some answers, good luck to everyone going through this nightmare

  3. Ali’s. Aren’t they wonderful little pills? I took my cancer very seriously. Went through chemo for increase of 4% survival rate. Told I could add 30% to my survival rate just by taking a little pill once a day. Piece of cake I thought. I tied every single AI on the market then Tamoxafan. When on AIs I was hit with every miserable side effect including vaginal atrophy and dryness. So I was put on Tamoxafan. All good for 6 weeks then developed wild mood swings. I was alienating everyone around me including my long suffering husband. I envied the women who could tolerate these drugs. But everyone’s physiology is just so different. We are not one size fits all. If a Dr tells you it can’t be a side effect well how does he know?? We are ALL different. I got to the point of weighing up quality of life maybe ending up in a psych ward, or divorce court, and becoming a little old lady before my time. So after giving every drug my best shot and weighing up quality of life over these drugs I made the decision to go drug free and concentrate on enjoying life, happiness, energy, diet and exercise. I am 8 years cancer free now. I may get mastastic cancer and I may regret my decision but at the end of the day my Oncologist could not tell me that if it did return it was due to being off the drugs. All the drugs can do is limit chance of recurrence. It is not a guarantee.

    1. This sounds exactly like my experience. I decided that I would take my chances and although my Surgeon was not happy with my decision to stop taking the AI Meds. She said that at the end of the day Quality over Quantity of life was a factor. At my age ( 80 ) it was a no brainer!!. I still have ongoing issues from the 12 months that I did take them, but they are minor and I can cope with them. Good luck with your problems.

    2. Sue
      This is encouraging for me. I am on my third month of Letrozole after trying anestrozole for 3 months. I’m sorry but I think that 16 side affects is a bit excessive. Every day when I put that pill into my mouth i feel like i am poisoning myself. I’m seriously considering going off the medication. The doctor told me last time that there are only three so only one more to try….but I don’t know if I can….it’s all so disheartening. My cancer was so small, they caught it quickly and I had the maximum amount of radiation allowed in my breast. I feel like if that doesn’t kill it nothing will. sigh…

      1. Hi Phyllis, in a last ditch attempt to keep me on something my oncologist put me on Tamoxafen – which is usually for younger women. For me it didn’t have the terrible side effects of AI’s and I thought thank goodness, I can finally take something. Then 6 weeks in I started having wild mood changes and was very aggressive . I persisted for as long as I could then weighed up my quality of life. The way I was going I was going to end up divorced if I stayed on this drug. I would never suggest anyone go off AIs. This is such a personal decision. After surgery chemo and rads I thought it was a piece of cake to take one pill a day for 5 years. I was wrong. Some women go through it with few side effects and cope very well. I just wasn’t one of them. It will be 8 years this year cancer free. But Breast Cancer is unpredictable. I know I am taking a huge risk. If you can tolerate them, stay on them.

    3. You’re a brave woman! I agree totally with you. I am one of those women who cannot tolerate these AI’s. What a horrible side effects. Lethargy, depression, stiff fingers when you wake up, aching knees, every part of your body hurting. This is no way to live life. I have to continue using this until I decide about surgery for this tumor in my breast. I feel like this drug has just swallowed up all my life force. Praying to get back to normal.

      1. Sandra, sorry to hear you are having a tough time with AI’s. It’s none of my business and you don’t need to respond but I was wondering why you have to decide about surgery?

  4. I am being treated for mets. For the last 1 1/2 yrs. it has stayed in my bones. Tumor markers are not normal but rise and fall in a range my Dr. is satisfied with. I am on Aromasin and Xgeva shots every 3 months. I am in agony. Every bone in my body hurts and the fatigue is overwhelming. My hands hurt, walking is tough because of my feet and hips. Reading this was almost a blessing to know I am not crazy for feeling like this. I find myself wishing I could take a break but am scared to do it. I am a young 70 who feels like a very old 90. God bless you all. This is a tough journey to endure.

  5. Carolyn you are not crazy. The side effects of these drugs can be debilitating, more so for some than others. That’s because our physiology is so different from one person to another. You are fighting hard to beat these Mets, and have endured these drugs for 18 months. Don’t give up on them. May I suggest you find a good integrative GP to compliment the care you are receiving from your oncologist to give you the best chance of beating this. My Inte GP gives Vit C infusions to cancer patients. I suggest you read this. Good luck and know you have a support system here.
    I hope this link opens if not Google for yourself Vit C infusions for breast cancer patients. I am not recommending a treatment, just giving you the information. Good luck…

  6. Hi. In 2016 I was diagnosed and treated for IDC left breast. It was a High estrogen driven, tiny tumor, caught early & removed. I tried anastrozole and couldn’t deal with the horrible hot flushes. It wasn’t something that came & went they just stayed. I couldn’t sleep, I was gaining weight as though I was a non stop eater and I was going to orthopedic doctors because no-one would admit the connection to my joint pains. So I stopped taking the anastrozole and all the side effects subsided. In 2019 I had another tiny tumor. This time in my right breast. Again it was IDC, very high ER & PR positive. According to my oncologist this new tumor was totally unrelated to the first one in 2016; it was a “new” cancer. While waiting my lumpectomy and brachytherapy etc. to be scheduled I was put back on Als. This time Letrozole. Again the horrible hot flushes but this time I would get so hot I would pass out. Again I told my oncologist & surgeon and like other people I was made to feel like I was exaggerating. Because I’m terrified of cancer and the thoughts of cancer coming back consume me daily, I agreed to try Aromasin. I’m reading here this is a “permanent” estrogen blocker. What does that mean and what are my risks now that I’ve been taking it for a little over a month? Not one of my doctors told me there was any difference in these medications, just that if one gives me horrible side effects we’ll try another. Please help, now I’m terrified all over again, not to mention very angry at how my doctors are sugar-coating all these medications.

  7. I tried Arimidex first and couldn’t stand the hot flashes, joint pain and relentless insomnia so I switched to Aromasin. Within the first 6 months on it I broke 3 toes and every one of my top teeth and 4 of my bottom teeth cracked off. I now have full upper dentures and they are horrible. My husband has had to give me the Heimlich maneuver many times because it is so difficult to eat and swallow correctly with these things.

    1. Hi Lynn….. were you given a bone density scan before starting the Aromasin? I’m just curious if you had osteopenia or osteoporosis? This medications are horrific. Sorry to hear you’ve had so many bad side effects, but thank you for sharing.

  8. I am not reading about bone meds given with the AI’s, are anyone getting shots or meds to strengthen bones? I am getting Xgeva shots every 3 months, started at every month but side effects of this drug can be just as bad as the AI’s.

  9. February 19, 2020
    I have taken Tamoxifen for 547 days. Currently, I am on a break for 30 days and am checking out if I can take
    this med every other day since there seems to be a lot left in your body being a steroid for a period of time. My only downside of taking this drug is hair thinning. I used to have really thick hair. So some of this may be my age of 72. I am now taking laser therapy with a bonnet. Before starting Tamoxifen my doctor wanted me on A!’s. I read all the whore stories and looked at all the lab trails. I drew a line where the Tamoxifen is less effective after 2 years while the A!’s supposedly have better longer life expectancy. I decided when I reach 2 yrs on this drug, I will look to see what else in on the market and their results and make a decision at that time. My surgeon, the best in Charlotte, was glad I chose Tamoxifen because the A!’s could cause bone fractures at my age. Luckily my cancer was small and I decided not to have chemo but went for the month of radiation. Two good check ups so far so ladies just keep reading those trials and see what might be new on the market. Pulling estrogen out of your body is not healthy. It’s there for a reason!!!

  10. Hi Ladies – I thought I’d put in my two cents here. As you’ve all noted, everyone is different when it comes to side effects. I started on 20mg Tamoxifen in 2015, and stayed on for two years despite severe leg and foot cramps. My oncologist said he never heard of this, (and he must be in his 70s.) I can’t understand how he wasn’t aware of this side effect, when all I had to do is google it and saw tons of women who suffered the same thing. After two years I switched to Letrozole and had almost every side effect out there. Which is weird because I’ve never been very sensitive to drugs / pain killers. Anyway, before long I felt like I was 90 (I was in my mid-50s), my hands were stiff and joints were sore – could hardly open and close them in the mornings, I had a mild depression and horrible nightmares (which I read some other women had) No hair loss or weight gain though. Had problems with my feet/ heels. After a while switched to Exemestane. It wasn’t quite as bad but did have a lot of problems with my feet, and I’m a walker, so that really disrupted my lifestyle. It felt like plantar fasciitis and other heel pain. Hands were still stiff with swollen joints. And cholesterol shot way up which is apparently another side effect. So after a year and a half on AIs I’m back on Tamoxifen for my final year. (done in June!) But just 10mg (1/2 dose) because of the leg and foot cramps. I try to do more with diet, exercise, getting natural aromatase inhibitors in my food (incl flaxseed) and intermittant fasting (some positive evidence there) So, yeah, AIs suck. Hang in there, everyone!

  11. Dear Friends,
    I’ve been on Letrozole for 16 days. I was diagnosed and treated for breast cancer in 2002, age 44. I had a double mastectomy, chemo, radiation and then my period returned so I elected to have a double oophorectomy. I was disease Free for 17 years. For weeks ago a lung biopsy revealed primary breast cancer. It’s a 2×3 cm tumor. I took Arimidex 17 years ago and almost couldn’t walk after a few weeks. So, I stayed away from AIs.
    I was hopeful that I may be able to tolerate AIs this time to starve my lung tumor. After 16 days of it in my system, I developed pain in my sternum that radiated across my chest. I woke up in the middle of the night with the most severe upper back pain of my entire life. My oncologist told me to hold my Letrozole for a week. I’m still nauseated and in pain but I have hope that I’ll recover.
    I read it takes about 2 to 6 weeks for estrogen production to be halted with the AIs. I was wondering if I actually was experiencing angina from the complete depletion of my estrogen. After all, the heart is a muscle and maybe I need hormones to keep it healthy. I’m not a melodramatic person or a hypochondriac. My acute pain was real and very frightening. I’m an ICU nurse of 36 years.
    Thank you, everyone, for sharing your experiences. As my dearest oncologist Dr. Brennan said to me in 2002,”You’re a statistic of one and you matter.”

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