Real talk: your hairbrush is probably overdue for a cleaning. Between dead skin cells, oils, and leftover product, it’s a breeding ground for grime that can mess with your scalp. But how often should you be cleaning it? Spoiler alert: more often than you think. Here’s everything you need to know to keep your brush—and your hair—fresh and clean, including when it’s time to trade your trusty brush in for a newer model.

How often to clean your hairbrush

As a general rule, you should clean your hairbrush every one to two weeks, but it really depends on a few things, says Lindsey Marie Zubritsky, MD, FAAD, a board-certified dermatologist based in Pittsburg, PA.

Clean your hairbrush more often if:

• You use heavy styling products
• You have long hair
• You deal with dandruff or an oily scalp

How to clean your hairbrush

The method for cleaning a hairbrush depends on the type, but no matter the brush, always start by pulling out the hair with tweezers, scissors, or just your hands, Dr. Zubritsky says.

If you have a brush with synthetic plastic bristles (which are easiest to clean, BTW), follow these steps, per Dr. Zubritsky:

• Put some shampoo, dish soap, or body wash in a large bowl of water and soak your brush for 15 minutes
• Rinse thoroughly afterwards, shake or squeeze the brush to remove excess water, and then allow to air dry
• For extra cleaning, you can spray the brush with isopropyl alcohol for disinfecting.

If you have a brush with natural bristles and/or wooden handles, you need to handle them with a little more care. After removing all the hair from the bristles, follow these steps, per Dr. Zubritsky:

• Add a gentle, mild shampoo or soap to a large bowl of water.
• Only dip the bristles in the water (keeping the wooden handles dry).
• Lather up the bristles (either with your hands or a toothbrush). You really want to give these natural bristles a thorough scrub since they have more nooks and crannies.
• Soak for15 minutes (again, keeping wooden handles dry).
• Rinse thoroughly afterwards, shake or squeeze the brush to remove excess water, and then allow to air dry.

What happens if I don’t clean my hairbrush?

If you’ve ever let a bunch of hair accumulate in your brush, you probably noticed it doesn’t work as well. But that’s not the only problem. A dirty hairbrush can also have consequences for your scalp.

1. It can clog hair follicles

Hairbrushes often collect dead skin cells, oils, and product buildup, Dr. Zubritsky says. This combination can clog pores and harm your scalp, leading to issues like scalp acne or folliculitis (i.e., when your hair follicles are infected or inflamed), she says.

2. It can lead to dandruff

“Your hairbrush is a breeding ground for bacteria and fungus, including Malassezia (a yeast known to trigger dandruff),” Dr. Zubritsky says. Even if you’re using anti-dandruff shampoo, yeast can still build up on your brush, and every time you use it, you’re basically putting that gunk right back on your scalp, she says.

3. It can irritate or damage your scalp

“Nothing good comes from using a dirty hairbrush, especially if you have a sensitive scalp,” Dr. Zubritsky says. “Dirt, debris, bacteria, old product, and dead skin cells can be transferred back to you scalp through your brush, leading to irritation and sensitivity issues.”

When to replace your hairbrush

We know–it can be hard to let go of your go-to hairbrush. But the health of your scalp depends on it. In general, it’s a good idea to replace your brush every six months. Here are some signs that your brush needs an upgrade, per Dr. Zubrtisky:

• The bristles or handles are damaged, bent, cracked, or missing
• Your brush isn’t working as well (when your brush isn’t working right, it creates more friction and traction on your scalp and hair, which can lead to damage)
• Your brush has a persistent odor (despite regular cleaning)
• Your hair appears more oily or greasy