Board Thread:Questions and Answers/@comment-26435358-20151222081947/@comment-24851346-20151228213923

You're forgetting how Demonic Energy takes care of all the nasties of sex for them. The ones in the Demon Realm are stated to be blessed by Undines, which should be enough to take care of all that stuff. Not to mention Monsters have a better constitution than most humans, and I doubt that their succubus energy would allow them to catch anything that gets in the way of sex, and they also transfer some of that power to their husbands during sex, so its likely a non-issue for men as well.