So, could your go-to formula really be the culprit of chapped lips? According to dermatologist Joshua Zeichner, MD, it's likely. “Allergic reactions and irritations to toothpaste are unfortunately common,” he says. “If you have chronically chapped lips, mouth irritation or burning, or even a rash around the lips that will not go away, you must consider whether it’s your toothpaste that’s having that effect.” As for blaming SLS-based formulas, Dr. Zeichner says that while the cleansing agent can cause allergic reactions in some people, ingredients like cinnamon and mint are also frequent culprits. That’s right: Your toothpaste’s minty flavor alone could be the reason your lips are chapped no matter how much Maybelline Baby Lips you apply. (What is life?) Bottom line: If you’ve tried everything under the sun and can’t seem to get your flakes under control, it might be worth switching up your toothpaste to an SLS-free one, like Sensodyne, and seeing how it goes. Just keep in mind that everyone has different reactions to ingredients, and that isn’t a guaranteed fix. And, as always, heading to your dermatologist is a much safer bet than consulting Reddit. (Yes, even if it is from the well-sourced information found on SkincareAddiction .)