Depends on the med, IMHE. When I was first sent home from the hospital, they had me on depakote. Well, it turns out that it was a toxic dose, so I basically overdosed. Didn't know it-I was too out of it. Dh and others around me started freaking out when I was walking around hallucinating and saying wierd stuff. Neuro had me go for a stat blood draw to measure my depakote level (yup, too high), and dh didn't give me any more meds until the following day. Also, had to keep waking me up all night to make sure I could wake up!

OTOH, one night I think I doubled my lyrica. Started having trouble breathing, so I panicked (or vise-versa). The neuro on call called me back and said that, if anything, an overdose would make me sleepier, not worked up. I was having a panic attack because of the fear of overdosing! He had me take the rest of my usual AEDs (keppra) and, sure enough, I calmed down after talking to the neuro and fell asleep just fine that night, no problem.

One night, from exhaustion (drove 10 hours during a move), I took my morning dose (300%) of cortef at bedtime. Didn't realize it at all, but it was one of those things that came back to me when I was falling asleep.....after I'd already had a seizure! I think that time, the OD of the wrong med stimulated the seizure! Baaaaad thing to do.

I have my med routine pretty down pat, but I take four different medications morning and four different at night, with slightly different doses each time. After four years, three mix ups isn't that bad, but the risks are scary!