I just started Citalopram (Celexa), Lisinopril (for HBP), Zetia, and Simvastatin. Since I started four days ago I have a condstant upset stomach, hearburn, indegestion, and diarrhea. I have been on Celexa for several months and they just switched me to the generic. Can the generic be bad for you if the brand name didn't bother you? I'm not sure which drug is the culprit, though. How can I determine which one it is? I went to a drug website and they said there are no ill side effects of Zetia. So I can rule that one out..?:confused: