Side effects seem to be different with two different brands of Li...

What someone told you about fillers is true. This can cause a person to be able to tolerate one maker's version of the same drug, but not another's. I had this experience with Metformin (anti-diabetic.) For 3 months I suffered terrible diarrhea after taking the drug for several years, I thought I was no longer tolerating it. Then I got a new fill of it, but this time maker was Sun Pharm. and I've not had the severe reaction. It DOES matter sometimes who the maker is and what fillers they use. I need to find out who other maker was and what fillers were used so I can avoid them in the future. The message to be taken from all these posts is: Listen to your body, and Don't think the doctor knows everything!
I am lucky enough to have insurance, but they want you to take the cheapest drug possible, like Lisinopril. I've taken Diovan without incident, but I betcha they won't want to pay for it. While Congress is going about healthcare reform (if they get time away from declaring National X or Y Day) they need to outlaw interference in prescription choices doctors and patients make.