"The skin peels when the top layers die and slough off," says Jessica Wu, M.D., a Los Angeles-based dermatologist and author of Feed Your Face. This can happen for many reasons, the number one being sunburn. "Ultraviolet rays from the sun actually kill off skin cells," says Joshua Zeichner, MD, director of cosmetic and clinical research at Mount Sinai Medical Center in New York City. "When this happens, the dead cells are sloughed off (in the form of peeling) so that new, baby skin cells can replace them." If you've ever popped a blister prematurely and seen the delicate skin underneath, you've seen this process in action.
But sunburn isn't the only cause of flaky skin. Dryness could also be to blame. "When the skin isn't well-hydrated, skin cells do not stick together as smoothly and they start to flake off," says Zeichner. Other culprits of peeling include topical skin medications (like retinoid creams and gels, which can treat everything from acne to wrinkles) and certain kinds of rashes. For example, people suffering from eczema (a chronic condition that results in dry, red skin) may also suffer from peeling and dryness. If you get a chemical or laser peel, you could also end up dealing with residual flaking.