4-year-old children always have diarrhea may be related to infection factors, but also may be related to food allergies, abdominal cold and other factors, the specific analysis is as follows: 1. Infectious factors: 4-year-old children may have diarrhea if their bodies are infected by bacteria, viruses, parasites and other factors, accompanied by abdominal pain, loss of appetite and other adverse reactions. 2. Food allergy: Children who have recently ingested new foods may have diarrhea all the time, which may be caused by food allergy, and need to take the child for allergen examination. 3. Cold abdomen: Children who do not keep their abdomen warm while sleeping may also have diarrhea. 4-year-old children always diarrhea may also have other reasons, it is recommended to take the child to the hospital in time for relevant examinations, clear causes and then actively treat the symptoms.