There’s A Grim Downside To Washing Your Hair Too Infrequently

A viral hair-cleaning hack may be doing more harm than good.

Hair training is a trick for achieving longer-lasting clean hair that has grown popular on TikTok, with #hairtrainingtips reaching 260.3 million posts and #traininghair reaching 280.2 million posts and counting. Many fans of the technique swear they can go weeks or even months without shampooing — a promise that’s especially tempting for those with oily hair. But does it actually deliver, and is this trend causing more harm than good?

Hair training is the practice of gradually extending the time between hair washes to train the scalp to produce less oil, which aims to make your hair look and feel cleaner for longer periods between washes. A major perk, as supporters of the trend claim, is to be able to condition your hair to fit your perfect wash schedule.

According to the pros, the answer is no. “While the concept sounds appealing, the science just doesn’t support it,” said hair transplant surgeon and dermatologist Dr. Hannah Kopelman. “If you’re not washing [your hair] regularly, what you’re really doing is allowing sebum, sweat and impurities to build up on your scalp.” That can lead to more hair falling out or other scalp issues, she noted.

Excessive oil and debris on the scalp can also lead to seborrheic dermatitis, a common skin condition that causes dandruff, inflammation and scaly patches, points out board-certified cosmetic dermatologist Dr. Michele Green. “Scratching it can lead to hair loss due to damaging the hair follicles,” she said.

Sebaceous glands, distributed across the scalp, are responsible for producing sebum, a natural oil that moisturizes and protects the scalp and hair from drying out.

“Sebum is actually a good thing — up to a point,” Kopelman explained. “When there’s an excess of sebum, it can lead to clogged pores, dandruff and even contribute to hair thinning.” Though your genetic makeup plays a significant role in determining how oily or dry your scalp naturally is, there’s a whole mix of other factors at play. Hormonal changes, stress levels, diet and even your environment can cause oil to accumulate faster on the scalp for some than others. “If you live in a humid climate or are going through a stressful period, you might notice your scalp getting oilier faster,” Kopelman explained.

Since sebum production is a natural process largely driven by genetics and hormones, how often you wash your hair doesn’t actually change the amount of sebum produced. “In reality, hair training doesn’t change the function of your sebaceous glands,” Kopelman said.

“When it comes to how often you should wash your hair, there’s no one-size-fits-all answer,” Green said. “It’s all about understanding your unique hair type and scalp condition.”

Generally, those with curly, coarse or dry hair can stretch the time between washes longer than those with thin, fine or oily hair. However, there are telltale signs that it’s time for a wash, like hair that looks greasy and feels heavy or limp, or if you notice dandruff or an odor caused by bacteria or fungus growing on the scalp.

Certified trichologist Shab Caspara also notes that other signs include roots looking piecey instead of soft and flowy. “If your scalp becomes sore after a few days of not washing or even the slightest bit itchy, it’s imperative to wash your hair,” Caspara said.

If you’re looking to extend by a day or two between washes, there are a few tried-and-true methods that Kopelman recommends to get you there.

Scalp gua sha, which uses a flat tool to gently scrape the scalp, promotes lymphatic drainage and helps dislodge sebum and impurities. Dry brushing with a natural bristle brush also works wonders, gently exfoliating the scalp to lift away excess sebum and debris that can clog pores while boosting blood circulation for healthier hair growth. Doing this before you wash your hair helps to loosen up any debris and sebum, making your shampoo much more effective, Kopelman said. “For most people, using these methods one to two times a week is sufficient. It’s important not to overdo it, as too much exfoliation can irritate the scalp,” she added.

Aside from steering clear of heavy styling products that can weigh down your hair and contribute to quicker sebum buildup post-wash, blow-drying using a lower heat setting and focusing on the roots is also a trick to help keep hair feeling less greasy between washes. “If you let your hair air-dry, the moisture left on your scalp can sometimes signal your sebaceous glands to produce more oil, almost as if your scalp is trying to make up for the natural oils that were washed away,” Kopelman said. “This can lead to that greasy feeling sooner than you’d like.” Though neither of these methods actually decreases sebum production, they help the roots feel less greasy by moving sebum away from the scalp to the strands.

Overall, hair and scalp experts advise against relying on dry shampoo as the primary method for managing oily scalps.

“Dry shampoo doesn’t clean the scalp or hair. Rather, it absorbs oil and adds to the products on the hair that need to be washed off,” Green said. While they’re safe to use once in a while to fix greasy hair in a pinch, dry shampoos shouldn’t be used several days in a row, as they can clog hair follicles by adding starchy buildup to the scalp. Instead of aerosol dry shampoos that typically contain irritants like alcohol and isobutane, Green recommends trying powder dry shampoos that are fragrance-free, and contain gentle ingredients such as cornstarch or arrowroot to absorb excess oil from the hair.

While the idea of hair training might sound appealing, it’s clear that experts aren’t on board. Whether you shampoo daily or twice a week, the key is to build a routine that suits your needs to keep your hair looking and feeling fresher for longer without compromising your scalp health.

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