But dermatologists say products designed for these purposes are much better options and warn that toothpaste may exacerbate skin conditions.

Because toothpaste is not formulated for the skin, it can lead to dryness, irritation and inflammation, potentially delaying the pimple healing process or worsening acne, they say.

To prevent pimples or treat them, the American Academy of Dermatology recommends over-the-counter products containing adapalene, azelaic acid, benzoyl peroxide or salicylic acid.

Toothpaste is not an effective treatment for burns or to whiten fingernails, either. While toothpaste may have a cooling effect, one study showed that it can worsen burns. As for your fingernails, it can cause irritation.