Do you wonder how often you should shampoo? “It all depends on your scalp,” says Dr. Heidi A. Waldorf, director of laser and cosmetic dermatology at New York’s Mount Sinai Medical Center. “If it’s oily, or if you have dandruff or other issues, washing daily may be helpful. You also may want to shampoo more in summer. Otherwise, you can probably get away with as little as once a week.” To keep hair looking great between washes, celebs like Blake Lively use Oscar Blandi’s Pronto dry shampoo. My hair is oily so I usually have to shampoo my hair once a day. What about you?