Beauty products have never been more advanced. But as people layer them up, experts have seen a rise in perioral dermatitis. What is the too-much-skincare rash, and what can you do about it?

Gigi Hadid does it. Selena Gomez and Amanda Seyfried do, too. Olivia Munn also used to apply toothpaste to her pimples but has since wised up to this acne treatment hack. The stars, they’re just like ...