Hyperemesis due to cannabis use is on the rise, particularly in areas with marijuana legalization. While classically it is seen in chronic, daily users, affected patients sometimes have been using cannabis for less than a year, and may be using it as infrequently as once a week. Patients present with bouts of severe nausea, vomiting, and abdominal pain. A classic symptom is relief with hot showers (due to activation of the TRPV1 receptors). Symptom relief in the ED involves fluid rehydration and ondansetron (although this often no longer works for the patient after multiple bouts). There are also many reports of successful resolution of acute symptoms with benzodiazepines, haloperidol, and topical capsaicin. Curative treatment involves convincing the patient to stop cannabis use. Therein lies the tip, which I just learned from a colleague – a good way to help the patient understand is to tell them they suffer from an “allergy” to marijuana– while some people may be able to use marijuana chronically, they cannot, as it will cause these symptoms. Cessation of cannabis use can result in symptom relief as soon as 12-24 hours but sometimes not for as long as 3 weeks. So let them know how long that “allergic reaction” can continue!