8 of the Worst Things You Can Do to Your Hair

It may seem like common sense, but a regular hairbrush and wet strands should never intermingle. "People often don't know that when our hair is wet it is elastic, making it able to stretch and weaken much more easily," says celebrity stylist Justine Marjan. Of course, there are detangling brushes specifically made for wet hair, but your basic boar bristle brush should be reserved for dry styling. "It's important to be gentle with wet strands, as they are much more fragile and can easily break or snag if we are too aggressive," Marjan adds.

Turns out the tip about sleeping on a satin pillow case isn't just some mane marketing ploy. "Sleeping on cotton pillowcases causes frizz and split ends," says celebrity stylist Cynthia Alvarez. It also soaks moisture out of hair. "Yes, it's soft and durable, but rubbing your hair against it is a bad idea. Use a satin or silk pillowcase instead," Alvarez suggests.

There is an ideal temperature that hair can be heated to before it literally burns. "It's a myth that the higher the temperature, the better when heat styling your hair," says Marjan. She recommends GHD hot tools, which are automatically programmed to the ideal heat styling temperature of 365 degrees and won't cause damage. The same goes for your blow dryer. "Unless your hair is thick and coarse, you can get away with using your dryer on the lowest heat setting that's not cold blast," says Holly Mills, hairstylist for Streeters. And while it may sound silly to say, never, ever use a hot tool on damp hair — because yes, people do this.

Marjan, Alvarez, and Mills all agree that trims are absolutely necessary to keep hair healthy, but the frequency actually depends on your specific head of hair. We've all heard that if your goal is growth, you should cut away split ends every four to six weeks, but Marjan says this isn't totally accurate. "Getting your hair trimmed often will not make it grow faster. This will just depend on your hair health, your growth cycle, and how you take care of it at home. The ideal time between trims will vary from person to person," she notes.

The same heat rules apply to water temperature as they do to heat styling. In the same way that hair can scorch when using hot tools that are turned up too high, hair can also fry if your water is too hot. If it doesn't actually burn your strands, Alvarez says that it can dry strands out, making hair brittle and more prone to breakage. "It also removes more oil from your scalp, which can lead to an overproduction of oil that can damage your hair at the root and cause excess shedding," Alvarez adds.

"Ponytails are a quick and easy fix for a bad hair day or a lazy one, but tying it up too tightly can pull at your scalp and damage your roots," says Alvarez. You also want to take a break in between pony styles. Constant tugging along the hairline can lead to traction alopecia. If the goal is simply to keep your hair out of your face, Alvarez recommends using pins or clips instead.

Similarly to the pillow case problem, your method of sopping up water after shampooing can lead to breakage. "We have to be delicate with our hair after washing. Roughing up the cuticle layer of the hair with a harsh cotton towel can cause too much friction, exposing the top layer of the hair, resulting in a dull appearance or frizz," says Marjan. Try a t-shirt or the Aquis hair towel as a drying substitute.

It's true that dry shampoo can extend the life of your blowout, freshen up second-day hair, and save you hours of styling time each week, but using it too much or too often can lead to scalp conditions and hair loss. Leftover particles can stay on the scalp, creating buildup and potentially blocking hair follicles. It's also going to soak up oil both on the strands and at the root, so if your hair is already on the dry side, focus your spritz on just the roots. "If you also have any scalp issues like irritation or a bad case of dandruff, then I would advise skipping the dry shampoo altogether. It can congest your skin and irritate it more," says Mills.