The Oulu-based researchers say they are the first scientists to prove that people with no history of mental health illness have hallucinated when they stopped taking varenicline.
Varenicline is designed to treat smoking addiction by reducing withdrawal symptoms and tobacco craving by acting on the same receptor in the brain as nicotine.
Health officials in the United States have previously raised concerns regarding varenicline-induced psychotic disturbances in persons with previous mood disorders.
The Finnish researchers’ findings are published in the current issue of the American Journal of Psychiatry.