Varenicline induced auditory hallucinations in a young female with bipolar disorder: a case report

BACKGROUND: Creating appropriate and sustainable treatment plans for patients with concurrent disorders presents a challenge to psychiatrists and addiction medicine specialists alike. Although varenicline has been found to be the most effective medication for smoking cessation and abstinence when compared to results from placebo medications, nicotine patches and bupropion, caution is needed when starting patients on this medication. With the high prevalence of concurrent mental health and substance use disorders in vulnerably-housed populations in Canada, it becomes increasingly important to advocate for increased guidance and research into treating concurrent disorders. CASE PRESENTATION: In this case, a young female patient provisionally diagnosed with bipolar I disorder was hospitalized for a manic episode in the context of substance use and medication noncompliance. She also endorsed a long history of tobacco, alcohol, cocaine, cannabis and ketamine use. Perceptual abnormalities, including auditory hallucinations, were not recorded at admission. In addition to being stabilized for bipolar diagnosis, the patient was started on nicotine replacement therapy on Day 7 of admission followed by initiation of varenicline for smoking cessation on Day 14 of admission. Soon after the varenicline treatment was started, the patient developed auditory hallucinations, paranoia and referential beliefs. However, her insight was intact, and she had minimal thought form disorganization. In this case, these symptoms were thought to be secondary to varenicline after the consideration of potential alternative contributors. CONCLUSION: The occurrence of side effects as a result of varenicline use in patients with diagnosed mental health conditions is rare and underlying psychiatric illness is not labeled as an absolute contraindication in the prescription of varenicline. However, it is important to advocate for increased guidance and research on the treatment of substance use disorders in patients with bipolar I disorder. Patients may also benefit from increased collaboration between psychiatric and addiction services as that may allow for earlier recognition and intervention of symptoms to minimize distress. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12888-022-04348-6.