The Scientist: Paradi Mirmirani, M.D., is a practicing dermatologist in Vallejo, Calif. who specializes in hair disorders.The Answer: First, let’s explore where the flakes come from. Doctors aren’t sure why some people get dandruff—itchy, dry, scaly scalp—and others don’t. It’s something of a headscratcher (pardon the pun) but is most likely a combination of genetics and colonies of mites that live on your skin.

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These mites, called Demodex, aren’t something you need to worry about in and of themselves. Most, if not all, people have them on their skin, especially in areas that have large oil glands, like around your hair follicles. It’s thought that some people are more sensitive to Demodex, or host a larger population of mites, resulting in inflammation that causes seborrheic dermatitis. That’s science-speak for redness, itching and scaly skin that flakes off your head and onto your black sweater.Dandruff shampoos work by knocking the Demodex population down a peg. More severe cases may require denorex or scalpicin, a topical cortisone solution, to dampen the inflammatory response. Stronger, prescription cortisones are also an option. One of these treatments is usually sufficient to keep the little buggers in check. But, unfortunately, to answer the original query, there’s no way to cure dandruff for good.MORE ON DANDRUFF FROM YOUBEAUTY.COMVideo: Dandruff and Oily SkinStress and Your ScalpThe DIY Dandruff Solution