Level 1: Causes of Infant Diarrhea Infant diarrhea may be caused by many reasons, including infection, allergies, improper feeding, etc. The most common causes are infections, including viruses, bacteria, and parasites. These pathogens can be spread through contaminated food or water and contact with infected people. In addition, if the baby is allergic to certain foods or milk powder, it can also cause diarrhea. In addition, if feeding is improper, such as overfeeding and changing milk powder too frequently,