Hi, I'm writing a story involving mental health and medications and I want to be as accurate as possible. I wanted to have a teen with childhood onset schizophrenia or some sort of mental illness that causes hallucinations. She's prescribed medication but doesn't take them on the belief that she is not sick, and that her mother is the one who is supposed to be taking them. In the end, her mother dies as a result of being forced to take these medications in unhealthy doses that her daughter is sneaking in her drinks and foods.

What illness(es) could the teen have and what medication(s) could cause fatality? If fatality is not likely, is there another illness the mother could have that would be worsened by taking a medication prescribed for delusions and hallucinations?