A 1.5 year old child’s sour poop may be caused by indigestion, which can be treated through dietary modification and medication. A common cause of sour and smelly poop in 1.5 year olds is indigestion caused by improper feeding, where food residue stays in the intestines for too long and ferments abnormally, producing a sour odor. In severe cases of indigestion, there will be intestinal flatulence, abdominal pain or diarrhea. The symptoms can be improved through diet and medication. 1. Dietary regulation: improve the diet structure, appropriate water, easy to digest light soft food, small meals, should not be too full. 2. Medication: Probiotics such as Bacillus subtilis granules and Bifidobacterium triple live bacteria are commonly used to improve indigestion. A 1.5 year old child with sour poop is recommended to consult a doctor in time to avoid causing adverse consequences. The above medicines should be used according to the doctor’s prescription.