Here’s something I wasn’t aware of till a few months ago. If you’re on a generic, do try to stick to the same supplier.
I have been taking lithium for bipolar disorder for several years, with no serious side effects. This summer, I started getting nauseated after taking it. My doctor ordered blood tests, but also suggested we might have to switch to a different medication. I didn’t want to, because lithium and Depakote both worked to stabilize my mood, but lithium also made me more calm and clear-headed. (I think it has an effect on ADHD, which wasn’t diagnosed at the time. But that’s another story.)
I researched everything I could find about lithium toxicity, and found that among all the other variables I was controlling for (exercise, water intake, avoiding alcohol and caffeine), it also turns out that generic lithium can have vary in the amount of active ingredient, composition, etc. One source recommended that patients stick with the same manufacturer for lithium. Sure enough, I had been switched to several different manufacturers around that same time, due to supply chain issues. (After moving from Wal-Mart to Walgreens, I had fewer problems with getting my prescription filled consistently.)
Obviously, I can’t say definitively that switching generic drug manufacturers caused enough variation in lithium blood levels to cause side effects to show up, but the timing suggests that *might* have been the case. It’s something to keep in mind.
I’m better now, blood levels fine. 
P.S. I like this site a lot. From a human-computer interaction viewpoint, it’s very friendly. Thanks!
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