Here’s What the Gray Fuzz Is on Your Hairbrush—It’s Grosser Than You Think

Listen, I’m not a monster—I clean my house (mostly), I floss religiously and I even once cleaned out a backed-up shower drain with my bare hand (don’t ask, it haunts me still). But there’s one area I had never given a second thought to: my hairbrush. That is, until I got this article assignment about the gray fuzz that builds up on hairbrushes. At first I was like, nah, that’s not me. But then I looked at my brush and realized I’m not just gross, I’m also wildly unobservant. My brush is coated in a fuzzy, gray blob that looked like it had crawled out of a dryer vent and was planning to unionize with the bathroom mold.

Naturally, I did what any rational adult would do. I picked it out with a bobby pin and pretended it never happened. But like a bad ex, the fuzz kept coming back. Turns out, that gray stuff? It’s not just lint. And once you learn what it really is, you’ll never look at your brush the same way again.

So I called in the big guns: Emmy-nominated celebrity hairstylist Dean Banowetz (aka Hollywood Hair Guy) and Anna Chacon, MD, a board-certified dermatologist, to give me all the germy details—and help me brush up (ha!) on my cleaning skills. So buckle up, my follicle-having friends. Read on for a slightly horrifying (and super helpful!) deep dive into your brush’s dirty little secret.

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What, exactly, is that gray stuff that appears on hairbrushes?

“The fuzz is a mix of hair, scalp oils, dead skin cells and dust from the air,” Banowetz says. But he says the key ingredient of this disgusting cocktail, the one that holds it all together (literally), is product buildup—think gunk left over from hair gel, putty, pomade, mousse, dry shampoo, hairspray, leave-ins and other hair styling products.

How does it work, exactly? “When we brush our hair, it’s typical for hair to shed, and it can get tangled in the brush. That, mixed with dead skin cells, which are also naturally shedded, create some buildup, and if you have applied haircare products to your hair, those products can also transfer to the brush,” Dr. Chacon explains. “Top that with dust or other environmental factors, and you get the fuzz.”

My hairbrush is starting to make a lot more sense. As a curly girl, I use a metric ton of product on my hair. No one asked, but my simplest wash-day routine involves a clarifying shampoo, a regular shampoo, a conditioner, a mask, a leave-in conditioner, foam and gel, then I scrunch out the crunch with a little hair oil and finish with a mist of hairspray. Now that I’ve typed that all out I think I may have fallen victim to way too many instagram ads.

But regardless of what your personal haircare cocktail is, the gray stuff is your brush’s passive aggressive way of saying “Clean me, please.”

Why is it such a problem?

That fuzzball isn’t just gross—it’s a full-blown hygiene nightmare. “It holds onto bacteria and yeast, which can transfer back to your scalp,” warns Banowetz. That can lead to irritation, breakouts and even infections. Plus, all that buildup can dull your shine, re-grease freshly washed strands and tug or break hair when you brush.

“Any sort of buildup that you are reintroducing to your hair and scalp needs to be addressed to protect your hair and scalp health,” Dr. Chacon says. Sometimes the fix is as simple as adjusting your cleansing routine—washing more often to break up product residue. But if you’re noticing flakes, itching, redness or irritation, it could be a sign of dry scalp or dermatitis. And if you have an oily scalp, the excess oil buildup can make the condition worse. Conditions like eczema, dandruff, and skin sensitivities can also be aggravated.

And your brush may be a big part of the problem. “Bacteria thrives in dirty environments, which can include your brush if the buildup is not properly addressed,” Dr. Chacon explains. A dirty brush can also snag and tangle hair more easily, leading to even more breakage.

So yeah, it’s not just a cosmetic issue, you might actually be sabotaging your hair. This was particularly upsetting to me, as someone who spends an embarrassing amount of time, money and mental energy trying to care for my fine, tangly, breakage-prone strands. The idea that I might be damaging them with my own hairbrush (the Curl Bounce Brush, which yes, I also bought off an Instagram ad—I may have a problem) actually makes me feel sick.

When does this gray stuff start to pop up?

Turns out it doesn’t take long. “Gray stuff can build up in as little as a week to 10 days with daily use,” Banowetz says. Dr. Chacon says it shows up faster if:

• You use styling products

• You don’t wash your hair often

• You live somewhere dry and dusty

• You have poor scalp health

• You have kids (or other people) who borrow your brush and don’t tell you

Um, check; check, check; I don’t think so?; double-check (children!).

How often should you clean hairbrushes?

This depends on your hair habits. Daily brushers who use product should clean their brush once a week. Less frequent brushers or minimal product users should clean their brush every two to three weeks

Also, not all brushes are created equal. “A paddle brush and round brush trap more buildup because the bristles are closer together,” Banowetz says. And if you’re using a boar bristle brush? That natural fiber is a magnet for oils.

But you don’t have to wait. “Cleaning your brush should be part of your regular haircare routine,” Dr. Chacon says. “Anytime you see any buildup, it’s time to address it and give it a cleaning.”

How to clean a brush

Good news: Cleaning your hairbrush is easier than assembling IKEA furniture and far less likely to result in tears.

1. Remove the hair. Use your fingers, a toothpick, a bobby pin or one of those tiny rake-like brush cleaners. A toothbrush works great too—finally, a use for that free one from your last dental visit.

2. Soak it. Fill a bowl with warm water and add a squirt of shampoo or a spoonful of baking soda. Let the brush soak for about 10 minutes. Banowetz recommends Ship-Shape brush cleaner as a solid cleaner too. Pro tip: If your brush has a wooden handle, don’t dunk the whole thing—just the bristles. Use a tall glass so the handle stays dry and doesn’t warp or crack.

3. Scrub and rinse. Use your handy toothbrush again to scrub between bristles. Then rinse thoroughly.

4. Air dry. Lay the brush flat, bristle-side down, on a towel. Let gravity and evaporation do their thing.

How to deep-clean a brush

You don’t need to deep-clean every week, but once a month or so? It’s a good hair habit. Especially if your brush is starting to smell like last summer’s beach bag.

Here’s how to deep-clean your hairbrush:

1. Do all of the above regular-cleaning steps. (No skipping!)

2. Add vinegar or clarifying shampoo. These ingredients can help break down tougher buildup and sanitize your brush more thoroughly.

3. Use tweezers or a fine-tooth comb. For removing trapped gunk that’s wedged in the base of the brush. It’s oddly satisfying.

4. Let it dry completely before using. A damp brush is a happy place for mold, and we’re trying to avoid fungal roommates.

Can you clean your hairbrush in the dishwasher?

Sure, you can—you can put pretty much anything in the dishwasher if you try hard enough—but should you? Only use the dishwasher for fully plastic brushes. Wood, boar bristle or metal brushes can get damaged by high heat or water pressure. Still, Banowetz doesn’t recommend it for any brush, saying it “can shorten the life of your brush or even melt parts of it.” And nobody wants a melted brush spaghetti’d around the dishwasher rack.

But however you decide to clean your hairbrush, the important part is that you’re doing it. That fuzzy gray blob isn’t a mystery anymore, and now that you know what it is (and how to banish it), you’ll never go back to brushing your hair with the bacteria equivalent of a dirty sock again.

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Sources:

• Dean Banowetz, Emmy-nominated celebrity hairstylist and founder of Hollywood Hair Guy Academy; email interview, June 23, 2025
• Anna Chacon, MD, board-certified dermatologist; phone interview, June 25, 2025

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