Psychadelic SwirlAccording to researchers from the FDA, drugs given for ADHD (attention deficit hyperactivity disorder) can cause hallucinations, even when properly prescribed and taken.  The research, published in Pediatrics (Vol. 123 No. 2 February 2009, pp. 611-616) looked at data from 49 different clinical studies and found that the drugs can cause the symptoms of psychosis and mania—including hallucinations.  The number of children experiencing side effects was small—11 out of 743 participants in the various studies (about 1.5%), but the effects can be severe or disturbing. In some cases the children experienced hallucinations where bugs, worms or snakes were crawling on them.  Participants receiving placebos in the various studies experienced no such symptoms.