And over-washing can come in two forms: First, you’re washing too frequently and, second, with a shampoo that’s too harsh. Washing too frequently often is the result of the aforementioned oily roots—but it can also be because you work out every day, live in a warm environment where you sweat more, or just personal preference. If you need more insight into how much you should be shampooing, take a look at our full guide to washing your hair. Using a too-harsh shampoo usually comes down to the fact that you are using sulfates. Sulfates are potent surfactants that provide that sensorially appealing lather and squeaky clean feeling—but make no mistake about it: There’s a good chance they are throwing off the natural balance of your scalp and potentially your scalp’s microbiome. Both of these can trigger your scalp to produce more oil. Don’t worry, though; there are plenty of sulfate-free shampoos that are formulated for oily hair, so you don’t have to sacrifice efficacy, either: Try our favorites. As for triggering more oil, it does so in several ways. First, the products themselves could be silicone- or oil-based, which would naturally cause the hair and scalp to look more oily. This is especially true if you apply too much or you layer these products without adequately removing the prior day’s. These products—especially if they are silicone-based—can also create a hard-to-remove coating around the strand. “Their main function is to create a physical barrier coating on the skin and hair that is resistant to water and air,” says board-certified dermatologist Zenovia Gabriel, M.D., FAAD. In addition to water and air, they can block your own sebum. This means your scalp’s oils sit atop the film and aren’t able to penetrate the hair, causing your hair to feel extra greasy. “The oil follicles on the scalp are controlled in similar ways to the oil follicles on our face and other areas like the neck, chest, and upper back,” says board-certified dermatologist Hadley King, M.D. “So, factors like stress that may increase oil production on our face may also increase oil production on our scalp.” See, when you let your scalp live with its natural oils for a while, it will stop signaling to your pores that they need to put in extra work. Sure, this may make for an awkward and greasy transitory phase, but most experts agree this takes about a month, according to anecdotal evidence. So, how often should you wash, you ask? Well, that just may take some guesswork on your part. So the most important thing is to be diligent about checking in on your scalp. “Literally go in there, part your hair at various points throughout your head, and look at your scalp: Is it red? Are there flakes? Do you see oily buildup? Make this a habit,” says Reslan. “The bottom line is you just have to pay attention to it. People don’t do this enough.” A good rule is that if your hair is red and painful, that’s a sign that it’s time to rinse. So, yes, silk’s most famous benefits usually have to do with frizz and styling, but the last part of Branch’s sage advice is key: These help your hair retain natural oils. More porous materials, like cotton, absorb oil from your face and hair as you sleep. Not only is this less hygienic, but it means you wake up with drier hair! Here are a few of our favorite silk and satin options.
