Peppermint oil is extremely cooling. If you want a real sense of this, add just a few drops to your bath water and you’ll feel cooled like you’ve never been before. In fact, you may actually find peppermint quite uncomfortable in the bath, no matter, how hot they day has been or how sunburned you are. While peppermint seems perfect for invigorating the mouth in the form of a toothpaste ingredient, mouth rinse, or as a chewing gum flavor, it does not lend itself well to an all-over body soak in the tub.