Does teething cause diarrhea as mil mentioned it's due to teething. School unable to accept him

Possibly. My firstborn had bad diarrhea and diaper rash when she was teething. Every few months she’ll have bad diaper rash and some diarrhea. Just ensure you apply your most trusted diaper rash cream (for me it’s Desitin purple, it works like magic, for others is Sudocrem, etc) after every diaper change. If you’re BF, ensure your diet is clean and not spicy. Although it is not scientifically proven that teething causes diarrhea I think. But just so happened to my LO and some of my relatives babies too. Many believe that the increased saliva produced during teething can cause stool to become slightly loose. Keep in mind, diarrhea can be a sign of a more serious infection so contact your infant's pediatrician if the stool becomes watery, because your infant could be at risk for dehydration.