I'm not prone to hallucinations but when I had a bad fever that would never break, I had semi hallucinations, like when I closed my eyes I saw sudden images of violence or other things in exact detail. And I could not fall asleep, when I started to I woke up all startled.

Also had real visual hallucinations when I had a bad reaction to Lamictal. Then I felt like total crap, almost flu like, bad body pains, sore throat, and I saw weird things that I knew weren't there but I still saw them. They didn't understand at first it was an allergy that could have killed me, they thought I had a benign virus.

I don't attribute this to mental illness at all since I never hallucinated when physically healthy.