Abstract : Chronic diarrhoea is described as diarrhoea lasting more than 4 weeks. The underlying causes are multiple and the diagnostic orientation depends on several anamnestic and clinical elements. The basic work-up includes biology and stool analysis. We present the case of a 14-year-old adolescent with chronic diarrhoea and weight loss for several months. Extensive complementary analyses were performed, all being totally negative. A careful repeated clinical history revealed that the patient had a significant nicotine intake, confirmed by a urine cotinine test. Withdrawal led to a resolution of the symptomatology. Nicotine consumption in the form of nicotine replacement products among young people is increasing rapidly. Nicotine has multiple health effects, including neurological, gastrointestinal and immune adverse effects.