Mirtazapine and Weight Gain in Avoidant and Restrictive Food Intake Disorder.

Avoidant and restrictive food intake disorder (ARFID) is a newly classified disorder in the DSM-5 that describes a pattern of restrictive eating across the lifespan that results in significant weight loss, nutritional deficiency, dependence on enteral feeding or nutritional supplements, or marked interference in psychosocial functioning.1 Currently, there are no evidence-based treatment approaches or medications for this disorder.2 We have administered a range of psychoactive medications to those with ARFID in our treatment program in an attempt to find an effective medication. One medication of interest has been mirtazapine because it promotes appetite and weight gain, decreases nausea and vomiting, and improves gastric emptying. Although mirtazapine is an off-label approach in a pediatric population and carries a black box warning for an increased risk of suicide, it is an effective treatment for depression and anxiety symptoms in adults and is generally well tolerated.3,4 There are no studies to date reporting on the use of mirtazapine in patients with ARFID.