Hey, you can be allergic to natural ingredients just as easily as you can be allergic to man-made ingredients! (Just think of all the food allergies people have -- peanuts, wheat, strawberries, etc.) I would say that if it stings, you probably shouldn't be using it because it's obviously irritating your skin in some way.... If you have sensitive skin sometimes you just have to try a few different products until you can find something that works for you!