I started on Anastrozole in November 2018- I was age 63. After about 3 or 4 months - the joints in my hands hurt so bad - I could not do my hobby (sewing). By June my pain level was at least a 7, also my toes & shoulders hurt as well. Other side effects included: insomnia, dry skin, dry hair, constipation, vaginal atrophy. The AI's suck all the moisture from your body - it blocks all estrogen being produced in the body (not all of it comes from the ovaries). I insisted the Oncologist change drugs. First she sent me to a Rheumatologist to make sure the hand pain was not arthritis. Which took more weeks - so finally in November (now 1 year on the drug) - I got switched to exemestane. After 10 to 12 weeks the hand pain reduced to a 1 on most days. If it had not - I would have quit the drug. I read that something like 40% of women on an AI - quit taking it in the first year because of side effects. The AI drug - reduces your reoccurrence level by 50%. So if your level is at 10%, then it goes down to 5%. They actually wanted me to take it for 10 years, but I declined. When I pressured the new doctor (my old one retired) as to how much it would reduce my reoccurrence level, she admitted it would be < 3%. So I decided I was done. I'm 69 now. I still struggle with some insomnia, but most of the other side effects were gone within 4 to 10 weeks. Keep in mind - different people have different side effects. I met a woman who had finished her 5 year & she told me she had 0 side effects the whole time. So you never know what side effects you will get with each drug. There are 4 (I think) AI drugs, for post menopausal women. For pre-menopausal, it's Tamoxifen. You have to trust your doctor.