Diarrhea after drinking yogurt is usually caused by lactose intolerance, cold stimulation, gastrointestinal sensitivity or expired yogurt: first, lactose intolerance, yogurt retains part of the lactose in milk during the fermentation process, and lactose cannot be absorbed directly by the body, and requires lactase for decomposition, some people lack lactase and are intolerant to lactose, so they will have diarrhea after drinking yogurt. Yogurt is usually kept at low temperature, so if you drink it directly, it will stimulate the gastric mucosa and cause diarrhea; third, sensitive stomach and intestines, yogurt contains many lactic acid bacteria that can promote gastrointestinal peristalsis and help digestion and absorption. This can lead to intestinal infection after consumption.