If you are severely lactose intolerant or have an allergy or sensitivity to dairy products, the this can quite easily manifest on the skin. For some people it manifests in digestive issues or stomach pain or cramps in the colon, or for others it can result in severe headaches and nausea, but for many, this issue will manifest as breakouts on the skin. But to simply say that milk or dairy products are a cause of acne is not necessarily accurate it really does depend from person to person.