Loperamide Misuse Mimicking Symptoms of Severe Malnutrition

Loperamide, an oral over-the-counter μ-opioid receptor agonist used to treat diarrhea, acts primarily in the gut and, when used as recommended, has little to no systemic effect. At high doses, it may cause a "high" like other opioids. Recent literature describes an increasing incidence of loperamide misuse and overdose in the setting of the US opioid epidemic. In this case, we describe a 16-year-old with anorexia nervosa who developed dizziness, syncope, and constipation at the time of weight loss. These symptoms were originally attributed to malnutrition; however, after weight restoration, her symptoms worsened. She did not respond to initial management of suspected postural orthostatic tachycardia syndrome (POTS). She then developed acute urinary retention requiring hospitalization. Her symptoms were ultimately found to be caused by chronic surreptitious high-dose loperamide use. Her symptoms rapidly improved after cessation. This case illustrates the non-specific symptoms associated with loperamide misuse and the potential overlap with other common adolescent conditions. Adolescent medicine clinicians must be aware of the signs and symptoms of loperamide misuse as well as familiar with recommendations for both the management of acute complications and the treatment of the substance misuse.