This question is not easy to answer with certainty. Similac Total comfort is an excellent formula but is a low lactose formula. So your baby not being able to tolerate this formula is probably not due to lactose intolerance. He does well on a soya formula except that he becomes very constipated indeed. What does the fact that he can tolerate a soya formula tell us? Most probably that your baby is allergic to cow's milk formulas. Giving him a stool softener is definitely not the answer to his constipation. In all likelihood he cannot tolerate any cow's milk formula, so he should move to a highly modified formula used for milk allergic infants such as Similac Alimentum.
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