I'm writing a story wherein a tox screen is performed on a body that washes ashore. The cause of death (not that the characters in the story know that yet) is an overdose--most likely unintentional--of...something that is not a drug. I'm thinking she was taking something like ridiculous amounts of vitamin C or some herb meant for 'natural abortion'.
What I need to know is if high levels of Vitamin C would show up on a toxicology report, and, if so, if there is some other herb that wouldn't. For the sake of a character's reaction, I need the cause of death to be initially mistaken. Also, if anyone knows what the fatal amount of whatever method would be for a 14-year-old at 115-120lbs, or how to find this information, could you point me in that direction?
I've searched various phrases, like "vitamin c overdose", "vitamin c in tox screens", as well as looked into other herbs such as tansy, blue cohosh, and pennyroyal (I thought maybe the girl could have been confused/ill-informed and consumed the oil directly, but that wouldn't really work for the story).
I know it actually sounds like I'm some kid whose condom broke, haha, but I truly am trying to write a story.