Hi @MaryJoan, I have been on Tamoxifen for 9 years so far. At my 5-year post-cancer oncology appointment I was advised that further studies have proven that staying on Tamoxifen for up to 10 years has benefits. I look to come off the drug in July next year. Main side effects that I have noticed is the 'mental fog,' I am very forgetful! But use a number of techniques to combat this and initially, I was reasonably moody until I got used to it - but in saying that once I went on Tamoxifen I came out of early menopause and started getting a normal period so moods may have been the result of that and not necessarily the Tamoxifen. I manage to successfully work full time and run 2 businesses as well as play sports etc so I would say Tamoxifen has been manageable in my personal experience and as mentioned previously, if its not working for you, you can just come off it :) Hope this helps somewhat.