Hi Dawnp, i use estrogen only hrt due to hysterectomy, I've had nausea on all doses which did go away after a few weeks of first starting hrt or increasing doses, but on high doses it was constant every day and quite intense, but I was never on a dose as high as yours, I just cannot tolerate high estrogen, so yes it's quite likely to be caused by the high dose, it's a common side effect, not sure if it's because it's unopposed, maybe someone who knows more will leave some information for you, I do now use progesterone,(but otc not prescription as my needs are different having had a hysterectomy) but lowering the estrogen long before I started progesterone took the nausea away for me, have you tryed lowering your dose?, I hope you get relief nausea is absolutely awful, I have a fear of vomiting so I couldn't put up with nausea personally I would rather suffer some of my menopausal symptoms on a lower dose than have nausea although some women suffer it from low estrogen, it's very frustrating trying to get the balance right Ive never got it right after 4 years of trying, hoping the nausea goes away soon for you x