I am allergic to antibiotics too (it's not fun is it?) and my daughter is allergic to red dye......some of us are just sensitive to chemicals and other things. I am 60 years old now and started my 'breast cancer journey' at 56 (officially) so I was post menopause. I was unable to take the aromatase drugs as they all had bad side effects for me and so now my doctors check my estrogen levels every six months by blood test. I have estrogen positive breast cancer BUT as of a couple months ago, once again, virtually no estrogen, no progesterone. I encourage women to get a baseline estrogen and progesterone blood test to see how much estrogen, etc. you have. In my case I feel a bit better because I know I have little estrogen to bring the cancer back and because I can't take the pills, at least that gives me a little comfort for now.