It's was kidneys. I was on Lithium. My dose was extreme though. My doctor didn't know wtf she was doing apparently and just kept increasing it. I had severe toxicity with 4.6 levels. I went in and saw her several times shaking like I had parkinsons and walking around looking like a drunk person hardly able to talk and her response was to increase it... anyway, it's highly unlikely for that to happen or get to that point. I just ended up calling an ambulance one night because I knew something was very wrong and she wasn't doing anything about it. I don't really have much memory of being in the hospital. Just a few brief flashes, having a seizure.

Not trying to scare anyone, just what happens when you have an extremely incompetent doctor, not necessarily a flaw with the medication