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    Brazilian blow-outs and keratin treatments are all the rage these days. Do you know how they work? And if they're safe?

    By Shelley Levitt

    Reviewed by Karyn Grossman, MD

    WebMD Magazine - Feature

    What You Need to Know About Hair-Smoothing Treatments

    Tara Kennedy's mornings were made busier by her strawberry-blond hair. Thick with tight curls, it expanded to Little Orphan Annie dimensions on even slightly humid days. Taming it took the 32-year-old lawyer from Long Island more than an hour and a half and a dozen styling products. "By the time I left for work, I'd feel exhausted and exasperated," she says.

    That changed when she spent $350 and three hours in a beauty salon on a keratin hair-smoothing treatment. "Now, twice a week I wash my hair, blow-dry it for five minutes, and flat-iron it for 12," she says.  "It's straight, shiny, and soft whatever the weather. I love it!"

    The Hair Smoothing Process

    Whether they're called "keratin smoothing" or "Brazilian" treatments, salon frizz-fighters work by breaking apart certain bonds in your hair, then gluing them back together in a sleek new pattern, says John Vater, a longtime colorist who owns Spa Adriana, a salon in Huntington, N.Y.

    If you magnified a strand of hair a few hundred times, you'd see amino acids arranging themselves in what looks like a ladder if the hair is straight, or a spiral staircase if it's curly. Disulfide bonds, or linked sulfur atoms, form the "steps" of those amino acids. The more disulfide bonds your tresses have, and the more erratically they arrange themselves, the curlier your hair.

    The salon process works like this: After a deep-cleansing shampoo, a stylist applies a straightening solution to the hair. Next, he blow-dries the hair straight and meticulously flat-irons it at a high temperature. That creates a waterproof seal that helps hair strands maintain their new shape for three to six months. It also cuts down dramatically on at-home blow-drying time.

    Are Hair-Smoothing Treatments Safe?

    Some keratin hair products contain formaldehyde, which is linked to problems including headaches, teary eyes, and skin rashes.

    Formaldehyde exposure is a bigger risk to people who work with it, such as salon workers, rather than people like Kennedy, who straighten their hair every few months. But the FDA advises consumers to "limit exposure" to products that contain formaldehyde. 

    Brush Up on Beauty

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