1. What is diarrhea in babies? Loose diarrhea in babies means that the stools of infants and young children become thin, even watery or muddy. There are many reasons for babies to have diarrhea, including infection, indigestion, allergies, etc. 2. What are the causes of diarrhea in 8-month-old babies? 1. Infection: Microorganisms such as bacteria, viruses and parasites can cause gastroenteritis and diarrhea. 2. Food allergies: If your