Hallucinations in the Context of Varenicline Withdrawal

"Mr. A" was a 43-year-old, well-educated, healthy man with no current or previous medical or psychiatric history, including no past alcohol dependence or drug abuse. Notably, his family history was positive for schizophrenia, with one brother suffering from the illness. The patient reported smoking 10 cigarettes daily for more than 20 years. Varenicline was administered at a dose of 0.5 mg once daily for an initial period of 3 days, followed by 0.5 mg twice daily for the next 4 days. The drug was then administered at a dose of 1.0 mg twice daily.

The patient reported headaches shortly after starting varenicline. However, he was able to stop smoking after 2 weeks of treatment and therefore reduced the dose of the drug during the third week of treatment, taking only 0.5 mg once daily for 4 days. He then discontinued treatment. After taking the last tablet of varenicline on the following day, the patient began experiencing symptoms of derealization. His symptoms then progressed to visual hallucinations of unknown, distressing people who he "shooed" away. At that point, Mr. A suspected that he was having a "realistic dream." He also perceived that he had a conversation with a deceased rock star while being conscious that the person in question was actually dead. He became distressed and presented to his general practitioner, and he was started on quetiapine (50 mg at bedtime) for 10 days. The symptoms of hallucinosis rapidly disappeared. When interviewed by a psychiatrist 1 month later, the patient showed no symptoms of any psychiatric disorder, and he was not taking any medication. He had also managed to remain smoke-free.

http://ajp.psychiatryonline.org/cgi/content/short/166/5/619-a?rss=1