Similac Sensitive Isomil Soy infant formula is great for babies with milk allergies. The soy-based formula helps calm the digestive system. Similac Sensitive Isomil Soy infant formula reduces gas and fussiness caused by feeding. Like all Similac products, the Sensitive Isomil Soy formula has the EarlyShield Advantage which provides babies with the nutrients they need to develop strong and healthy bodies. Formula comes in a ready-to-feed liquid or a powder.