Lithium. I was on the max dose (1800mg) and it shut down my kidneys because my levels were really toxic. I forget what they're supposed to be but mine were around 4.3 or something like that.

I was vomiting several times a day, incontinence (Lost control of my bowels sorry for the TMI) shaking so much I looked like I had parkinsons and kept falling/having balance issues.

I ended up in the ICU for a week on dialysis, don't remember much of it. Had seizures while I was there too.

Never. Again.