16 Hair Myths You Need to Stop Believing

Whether you've got long locks or a trendy pixie, you probably have your own unique hair challenges—maybe it's a weird cowlick or unruly curls. In any case, separating hair fallacies from facts will help you concentrate on things that will actually help your hair grow healthier and look better. Here, myths about your hair, and how you can use the truth to your (beautiful) benefit.

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"Trimming your hair doesn't affect growth," says Joshua Zeichner, MD, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City. "That happens at the scalp." But there's a reason experts suggest trimming your hair every six to eight weeks: "Frayed ends make hair look thinner and cause breakage, so when you cut them off, your hair appears fuller," says Melissa Piliang, MD, dermatologist and hair specialist at the Cleveland Clinic.

This one only seems true because one gray usually means more grays. "This myth probably started because people plucked one gray hair, then noticed more afterwards," says Dr. Piliang. Sorry to be the bearers of bad news, but more silver strands would have surfaced no matter what—you can't blame the plucking itself.

Still, that's not a license to launch a full-on plucking war on your grays. "Your hair will become weaker if it's plucked too much over time, and it'll eventually stop growing back," warns Dr. Piliang. "That's not a big deal if you're plucking here and there, but it'll add up if you start going gray all over." Time to celebrate your silvers or book an appointment with a colorist

Don't blame the shower: If your hair is going to fall out, it will simply fall out somewhere else, albeit somewhere less noticeable (thanks, clogged drain). "This is the biggest myth I hear," says Dr. Piliang. "People often lose hair in the shower, so they associate shampooing with shedding." Problem is, if you cut back on washing in an effort to spare your hair, you can actually make the problem worse. "Oil buildup can cause inflammation, which stunts hair growth."

Address the real problem: "Stress is often the culprit behind shedding—divorce, surgery, a death in the family can make it more severe," says Dr. Piliang. Try these eight natural stress relievers, and add a few drops of essential oils, like lavender, tea tree oil, and rosemary, to your shampoo; they may stimulate hair growth, according to a Journal of Cosmetic Dermatology review.

If you've ever groaned at the idea of running a brush through your hair 100 times a day, you'll like this one: there's no value in brushing your hair more than you already do. In fact, excessive brushing may do more harm than good. "Over-brushing can damage your hair's cuticle," says Dr. Piliang. (That's your hair's outer, protective layer.) Brush your hair when it's knotty, but leave it alone otherwise.

Bleaching is indeed one of the worst things you can do to your hair, but not all types of color treatments should have a bad rep. "Removing color from the hair makes each strand thinner and more prone to breakage," says Dr. Piliang. But adding color actually plumps up your strands, making your locks look thicker. "I tell my patients it's okay to color their hair, as long as they're going darker."

Watch: DIY Beauty: How to Refresh Your Hair Color

"The main concern with dyeing your hair during pregnancy is the risk associated with inhaling ammonia, not the risk of it being absorbed into your scalp," says Carrie Ann Terrell, MD, an OB-GYN and professor at the University of Minnesota. "But the levels of ammonia are so low that it's not a problem, especially if you go to a salon, which will have industrial strength ventilation." Still, some women prefer the natural route. Henna is a plant-derived, ammonia-free dye, making it a favorite among pregnant women.

Most people think healthy-looking hair is all about external factors like the weather or the products you use. But what you eat affects your hair more than you think. "It takes your body a lot of energy to grow hair," says Dr. Piliang. "It needs nutrients." That means if you're on a restrictive diet, your body won't be able to dedicate energy to your hair, since it'll be too busy worrying about your essential organs. Make sure you're getting enough carbs, protein, and healthy fats, and pay extra attention to zinc, iron, and vitamin D. "They're crucial vitamins for hair growth, and a lot of women are deficient," says Dr. Piliang. Talk to your doctor about a supplement if your levels are low—especially if you don't eat red meat (which is loaded with iron).

Related: 6 Nutrients for Healthy Hair

"It's fine to switch shampoos, if you like different effects (one is anti-dandruff, one is volumizing, and so on), but it's perfectly fine to use the same shampoo every time you wash," says Dr. Piliang. As for that my hair looks so great with this new shampoo feeling? You're probably just liking the novelty: Shampoos do have different effects, says Dr. Piliang, but it's not necessary to switch unless you want something new.

We're used to equating flakes with dryness, so it's an easy mistake to make, but it's an oily scalp that usually goes hand in hand with dandruff. "Dandruff is caused by a type of yeast that tends to overgrow in an oily environment," says Dr. Piliang. "Dandruff is your body's reaction to the yeast." That's a problem if you cut down on washing in an attempt to diminish dandruff: use an anti-dandruff shampoo, but don't scale back your suds sessions.

• Shampoos don't necessarily need to lather to get the job done. "We're just used to associating a lather with cleanliness," says Dr. Piliang. But sulfates, the foaming agent added to many shampoos, can fade your color if you dye your hair. What's more, there's some debate about possible harmful effects. The American Cancer Society has deemed sulfates safe, but some lab tests suggest sulfates might pose a cancer risk, explains Mitchell Kline, MD, assistant clinical professor at the Weill Cornell Medical College.
• If you prefer to play it safe (but still like that sudsy sensation), try a sulfate-free shampoo that has glycerin. "Glycerin creates the soapy lather a lot of people like, with no known risks," says Dr. Kline.

Yes, you should spare your hair the blast of hot air, but sometimes you just need it to be dry in 15 minutes. But what if we told you that air-drying isn't all it's cracked up to be? An Annals of Dermatology study comparing blow-dried hair to naturally-dried hair found that blow-drying causes more damage to the hair's surface (as expected), but air-drying can create damage deeper within strands. Researchers say that the interior of the hair swells when exposed to water for extended periods of time, possibly creating more damage than heat styling. (Yes, our minds were blown, too.) Your best bet, according to this study, is to use the lowest heat setting on your dryer (or hold it at least six inches away from your hair), making sure to move the dryer continuously, so you don't concentrate heat on any one spot for too long.

Only if you apply oil to your scalp: "Oils applied to the ends of the hair will add shine and luster," says Dr. Piliang. Even better: Unlike products that sit on the hair's surface creating the illusion of healthy hair, some oils have the ability to penetrate the hair's cuticle and actually make it healthier. Coconut oil was shown to protect against bleach, heat, and UV damage in a Journal of Cosmetic Science study; and argan oil was shown to protect against hair lightening-induced protein loss in a Journal of Cosmetics, Dermatological Sciences and Applications study. Mix 20 drops of pure argan oil with 3.5 fl oz. conditioner (about the size of a bottle you'd carry-on a plane) for the benefits without the grease, says Robson Miranda da Gama, professor of cosmetology at Santo Amaro University in Brazil, and author of the argan oil study. He suggests this mixture for all hair types.

First you heard that you should wash your hair every day, then you started hearing that you should suds up every other day. Throw all the hair-washing rules out the window, and actually pay attention to the look and feel of your hair. Everyone's hair is different. If your hair is oily at the roots, wash it. If not, skip washing until you start feeling greasy. People with dry hair may want to let their scalp become slightly oily to ensure they're not over-washing it, says Dr. Zeichner.

Related: Cutting Back on Shampoo? 15 Things You Should Know

Here's a little biology 101: If you're a man, your mother gave you an "X" chromosome and your father gave you a "Y." (Women receive two Xs.) "Many people think male pattern baldness is an X-linked trait, passed down from the mother's side," says Luis Garza, MD, assistant professor of dermatology at Johns Hopkins School of Medicine, who studies balding. But you can't blame mom for this one: "We suspect multiple genes, from both mom and dad, contribute to baldness," Dr. Garza says.

Related: 21 Reasons Why You're Losing Your Hair

"The idea is that hats cut off circulation to the scalp, causing hair loss," says Dr. Zeichner. "But it's just an old wives' tale." Male pattern baldness is caused by genetics, and is turned on by things like high testosterone and stress, explains Dr. Garza. "People probably just noticed hair in their hats and made the false connection," he adds. That doesn't mean you'll need to hide under your hat if you see the first signs of balding: Dr. Garza says a minoxidil (brand name: Rogaine) regimen works preventively, not just after-the-fact. (It can be used by both men and women.) There are also other treatments for male pattern baldness.

If you're like most people, you exit the shower, immediately reach for a towel, and start rubbing your hair vigorously. Don't. "Towel drying is rough on your hair, and can promote breakage," says Dr. Zeichner. Instead, gently squeeze your hair with a towel, and then comb it with a wide-toothed comb to remove excess water.