When we first heard about dry shampoo, we thought our lives had changed forever.
We’re not exactly sure why washing our hair is so unappealing, but for the most part, it’s an obnoxious ritual. Dry shampoo seems like an excellent alternative; if you’re running late and you don’t have time to run through the shower, why not give your hair a quick spritz and be on your way?
Unfortunately, dry shampoo is problematic—from both scientific and functional standpoints.
These products work by soaking up grease and oil, but they’re not nearly as effective as soap and water. If you decide to forgo “wet washing” indefinitely, you’re going to run into a few issues right away.
To understand why, let’s consider the typical ingredients of popular dry shampoos. Most contain cornstarch, which binds to sebum, the oils created by your scalp.
To keep the cornstarch from caking together, many formulas also include magnesium stearate, along with a sizable dose of kaolin, a soft clay that reduces reflectivity. That makes your hair and scalp appear less shiny (and therefore less gross).
Most spray-on dry shampoos also include alcohol and petroleum, which propel the ingredients out of the bottle. The alcohol helps the mixture evaporate quickly.
Together these ingredients prevent oil from building up on your hair and keep your locks from looking greasy. But they don’t magically leave your head—they stick around, leaving a light residue on your scalp.
The good news is that the residue is fairly safe.
“Most shampoos today developed by major cosmetic houses are very safe, whether they’re wet or dry. They’re compounded so you can use them without problems,” said Wilma Bergfeld, MD, in an interview with Cleveland Clinic. “The question is whether it’s important to clean the scalp, and that answer is yes.”
The bad news? Dry shampoo certainly isn’t a substitute for wet shampoo.
“Your hair and scalp needs to be washed and rinsed intermittently to keep it clean,” Dr. Bergfeld said. “The scalp collects chemicals and pollutants both from the air and from cosmetic care products, and if you only use a dry shampoo, the cleansing is only minimal but it does freshen the hair by removing oils.”
Given enough time, your dry shampoo habit could make your hair more brittle, leading to damage and hair loss. It also doesn’t do much for your scalp, since it’s designed to improve your appearance, not to act as a complete cleanser.
Dry shampoo “deposits substances to coat the follicle that can build up,” L.A. dermatologist Sonia Batra told The Atlantic. “The resulting inflammation can weaken the follicles and increase shedding. These products can also cause hair follicles to stick together, so that a hair that would normally shed during brushing may take two or three strands along with it.”
If you’re going to use dry shampoo, make sure to use it correctly.
Dermatologists recommend spraying only the oily part of your hair, not the scalp. Don’t use dry shampoo for more than two days in a row, and if possible, opt for the non-spray shampoos, since they don’t contain alcohol or petroleum.
Finally, the most important—and disappointing—piece of advice: Don’t expect to see the same results you’d get from a typical cleaning.