Depending on how frequently you shift your shade, it could be time to give your hair a summer vacation from the salon. The pigments used in specific tones can actually stain the hair follicle, making that journey from brunette to blonde and back again all the more difficult—not to mention, damaging on your strands.
"Once you take your hair dark, going back light will cause breakage, so you should wait six months before doing that," says hair colorist Beth Minardi, who works with stars like Cameron Diaz, and is the co-founder of New York City's famed Studio B Salon. "Dyeing light hair a darker color is easy, but to go back is much harder. Make sure to condition the hair all the time at home, and have regular trims to keep it healthy."
In the case of a redhead wanting to go platinum—a la Gillian Anderson—you'll have to consider the variations of color in your auburn before making the plunge. "The hair can take on pink or orange tones depending on the dye that was used," Minardi says. "To get back to blonde, your hair has to be pre-lightened, conditioned, and toned." Meaning, the more downtime between the two, the better.
Though taking a flaxen hue to a deep brunette is a much easier process, Minardi recommends gradually darkening your strands with lowlights over an extended period. "Even if you take it to your natural color, it can be shocking on the eyes and show up as black," she explains. "The best thing to do is to lowlight it with dark pieces throughout the hair, that way the eye adjusts more gradually. I can do it in one day or several days depending, and sometimes, just the lowlights alone end up being plenty."
And if you've dipped in ombre highlights, they're typically subtle and concentrated on the ends, so you won't need to take more than three to four month breaks between touch-ups. Regardless of your end color, you'll need to invest in a protein-rich conditioner like the Minardi Nourishing After Wash ($27; loxabeauty.com), as well as a color-depositing conditioner to prevent fading. "Use it every fourth time you wash your hair," Minardi advises. "You'll literally be toning your hair at home."