Washing your hair every day isn’t necessarily healthy for your strands or scalp. Over-washing can strip your hair, leaving it dry, dull and brittle. But if you’re skipping washes every few days to give your hair a break, you might feel greasy or need the occasional pick-me-up. Enter: Dry shampoo.

Dry shampoo has seemingly revolutionized the hair care industry by offering a bridge between healthy hair that’s washed infrequently and day-three or -four hair that is just a little too dirty for comfort. Although the product is intended to help you maintain a healthy wash routine while refreshing dirty locks, dry shampoo might not be as safe to use as you might think. Frequent dry shampoo use might be causing other kinds of hair and scalp damage than the type you’re trying to avoid.

Dry shampoo and its uses

Dry shampoo is intended to absorb excess oil in your hair—a trick that’s particularly useful if you’ve skipped a few washes in a row and your hair is looking a little limp and greasy. However, despite its name, dry shampoo isn’t really shampoo. It’s merely a temporary substitute!

When you apply dry shampoo, the product works to trap oils on your strands and the surface of your scalp. This can help your hair look and feel less greasy. However, it does not actually remove the oils from your hair or scalp entirely. Some of the product and trapped oils sit on the scalp until you wash them out.

Dry shampoo comes in a few different forms, the most popular of which are loose powders and aerosol sprays. They’re typically made with an alcohol or starch base, which helps the product trap grime on your hair. They may also include synthetic fragrances and other ingredients to promote pleasant smells or trap oil more effectively.

The risks of dry shampoo

Although dry shampoo can offer some benefits—such as fresher-looking hair, less-frequent washes and less water usage—it isn’t the best product for everyday use. It can actually pose a few risks, particularly to your scalp.

Scalp irritation is the major concern surrounding frequent dry shampoo use. This is because of how the product is designed to work.

The scalp sheds dead skin cells like the rest of the body does, and oils and product residue build up over time. Although some oil is necessary to coat your strands and make them shiny and soft, it can quickly turn into a problem if left to mingle on your scalp with product buildup and skin cells for too long.

When you use dry shampoo, you’re essentially creating a thin layer of dirt and grime on your hair and scalp. While this is usually okay for a day or so, the longer this layer of buildup persists, the more damage it can do to your scalp. One of the biggest concerns is dandruff, because yeasts on your scalp can feed off the oils trapped there and cause flakiness.

This layer of buildup can also lead to clogged hair follicles, the result of which might be itchiness, inflammation or pain. You could even develop acne on your scalp if the buildup traps bacteria inside your pores. Over time, repeatedly clogging your follicles may cause damage to the follicle, potentially leading to hair thinning or loss.

Finally, some dry shampoos have intense staying power, meaning they can be tough to scrub out of your hair, even when you do wash it. Using a clarifying shampoo once in a while can help in this case, but you don’t want to use these intense products every time you wash, or you’ll dry out your hair.

Essentially, dry shampoos can coat your hair and scalp—making your hair dirtier, not cleaner—and prevent your scalp from breathing and staying healthy.

Dry shampoo isn’t all that bad

It’s important to note that the occasional use of dry shampoo is unlikely to make your hair fall out. Dry shampoo mainly becomes cause for concern if you’re applying lots of it every day and not washing it out properly.

As a general rule, dry shampoo should only be left on the hair for up to two days. After two days, you should wash your hair thoroughly to remove the buildup of oil and hair products and let your scalp breathe.

Proper application is also extremely important. Many people apply dry shampoo too close to their roots, which makes the product build up even more on the scalp instead of throughout the hair. By following the instructions and spraying dry shampoo far enough away, you can minimize the buildup that occurs.

Additionally, be cautious when buying dry shampoos. Some products use natural ingredients that are less irritating to the scalp, while others use harsher chemicals that worsen scalp problems faster and are harder to remove.

And, finally, remember that if your scalp is already feeling inflamed or itchy, pass on the dry shampoo and just wash it—even if you were trying to stave off washing for another day. The itchiness you’re feeling is a sign that your scalp is experiencing too much buildup and irritation, which can only be remedied through a good, cleansing scrub.