Hi In this age group, most common cause of diarrhea is viral, and mostly rota virus. Rotavirus vaccine prevents severe forms of such diarrhea. How ever there are some more viruses too that can cause diarrhea. Teething is not known to cause loose stools in this frequency of 6 times a day. What ever be the cause, you should be worried of dehydration part as you already are aware of. To prevent dehydration, - continue breast feeds - give him lot of fluids like porridge made of rice/ sago etc, vegetable soups, dal water, plain water and ORS. - give him rice based food, mashed potato and lot of curd. Curd is very good during diarrhea as it has probiotic bacteria naturally. Do not be under false impression that it causes cold. - Avoid fruit juices/ formula milk/ cow`s milk. Be sure he passes urine atleast 4 times in a 12 hour period. If he has vomiting also, you may need to give him medications like Domperidone syrups. If at any time he becomes tired/ passes very less urine/ food intake is less/ activity is less, do not hesitate to take him to the doctor. Hope my answer helps you. Wish a speedy recovery for your kid.