Using Hair Serum
Why you can skip it: Hair serums often contain silicone, says David Steinberg, a cosmetics chemist and a consultant for the cosmetics industry in Plainsboro, New Jersey. Silicone is a slippery ingredient that lubricates hair and adds shine. Once you step outside into the heat, you start sweating and your scalp begins to produce more sebum. "The serum mixes with these and just makes your hair look flat and oily," says Elie Camoro, a stylist at the Frédéric Fekkai Fifth Avenue Salon, in New York City.