In testing, from 15% to 21% quit because of intolerable side effects, and a majority are either overstimulated (insomnia,anxiety), or get detached, listless, tired or feel sedated.

   Another 10% suffer signs of neurological impairment, including tremors, twitches, and tics.

   Some side effects get better with time as the brain adjusts to the chemical intrusion, others do not.

   More rarely (probably less than 1%) the side effects are much more serious include bizarre behavior and suicidal impulses.