Serotonin syndrome induced by the combined use of metaxalone, phentermine, and duloxetine: A case report

Serotonin syndrome is a potentially life-threatening condition caused by increased serotonergic activity. Although this condition is commonly associated with certain antidepressants, this report describes a case of serotonin syndrome induced by the combined use of metaxalone and phentermine with duloxetine and bupropion. Our patient developed serotonin syndrome following the administration of metaxalone for severe back spasms. Symptoms resolved following the discontinuation of these medications, provision of supportive care, and administration of lorazepam and cyproheptadine. This case report adds to the existing literature, as studies on metaxalone-induced serotonin syndrome are currently limited. This case report also highlights the importance of monitoring polypharmacy, especially when prescribing less common medications such as metaxalone as well as weight-loss medications such as phentermine.