Hello doctors, my son is 18 month old and recently i have started giving him cow milk but he is refusing, right now he is only used to formula milk so how should i start giving him cow milk , can i mix cow milk with formula 50-50, will it be fine????, won't mixing will cause any digestive issues? because directly he is not taking cow milk in bottle not even through glass , just after one or two teaspoon he refuses cow milk.