Teen's severe vitamin B1 deficiency linked to chronic cannabis-induced vomiting

A 15-year-old who had been smoking cannabis for three months repeatedly visited emergency and primary-care facilities with persistent nausea, vomiting and a 25-30-pound weight loss. Initial treatment focused on anti-nausea medication and fluid replacement, but his neurological status worsened, showing confusion, slowed speech, brief unresponsiveness, rapid eye movements and difficulty walking. Imaging failed to reveal a cause, yet clinicians recognized the classic triad of Wernicke encephalopathy—nystagmus, ataxia and mental changes—often tied to severe thiamine deficiency.

Suspecting that chronic vomiting from cannabinoid hyperemesis syndrome had depleted his vitamin B1, they gave him intravenous thiamine every eight hours for two days plus oral supplements for four days. Within a day his eye movements and cognition improved, allowing discharge. He agreed to cease cannabis use, later regained his lost weight and returned to normal brain function.