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What Causes Hair + Scalp Odors

Discover the science-backed ways to keep them at bay Read More

Odors on the scalp can be the result of various factors including environmental stressors, emotional changes, and lifestyle choices (think: pollution, heat and humidity, regular physical activity, and extending time between hair washes).

But what exactly happens in the scalp and hair to cause malodor in the first place? Keep reading to find out.

top causes of hair + scalp smells 

This probably won’t come as a surprise, but one major cause of odor is perspiration, aka sweating. When you sweat, the sebaceous glands inside each hair follicle produce more sebum than usual. But sebum and sweat aren’t creating the malodor—it’s the microbes on the scalp, says Rita El-khouri, VP of Innovation at K18. 

“What ends up happening is the scalp microbiome will start to eat the sebum that's being produced by the body. Then you'll get short-chain fatty acids that have a horrible smell as a combination of the output,” she shares.

The same can be said when you forgo regular hair washes, adds Rachael Williams, Senior Scientist at K18. Excess sebum and oil are “food for bacteria.” This bacteria breaks them down, increasing the smell in the process.

 “Other things like UV can also break down oil and sebum on the scalp, so that can increase the smells that are present,” says Williams.

how to treat + prevent smells 

The key to keeping hair + scalp smells at bay is maintaining a balanced scalp microbiome. The simplest solution is prioritizing your hair and scalp health by washing it based on your unique lifestyle.


According to Williams, it’s important to “romanticize your haircare routine,” so it becomes less of a chore and more of a fun mainstay in your self-care regimen. It can be as easy as taking an intentional approach to wash day, like giving yourself a slow and gentle scalp massage from front to back, to promote blood circulation in this often overlooked area.

“The scalp is a very static part of the body,” says Williams. “It moves less than other body parts and isn't subject to the skincare regimens and touch our faces receive.” She adds, “It's good to really work your fingers into the scalp during hair washing, focusing on increasing circulation in the scalp, benefiting both your skin and hair follicles.”

Another tip: take your time rinsing. The more thorough you are with rinsing away shampoo and conditioner, the better chance you have of removing potentially irritating residue.

And of course, choosing a shampoo that's non-stripping and pH-optimized—like K18’s PEPTIDE PREP™ detox shampoo and DAMAGE SHIELD pH protective shampoo—is also vital to ensure a safe and effective wash.

the ultimate game changer for hair + scalp smells

In addition to incorporating K18’s in-shower shampoos and conditioner, consider adding K18’s latest groundbreaking innovation—AirWash™ dry shampoo—to keep your scalp healthy and odor-free. 


Powered by smart-release odorBIND biotechnology™, this unique formula is scientifically proven to recognize, suspend, and eliminate odors for up to 3 days* and leave behind a light, easily layerable fragrance. Plus, translucent microbeads absorb excess oil without a white cast or starchy buildup.

“AirWash™ has oil-absorbing translucent microbeads that help remove the oils before all the detrimental stuff starts to happen,” says El-khouri. “We also have an odor-control protein in there to grab odors as they start.” 

Unlike many traditional dry shampoos, AirWash™ is a non-aerosol, scalp-friendly formula that delivers a high-performance clean without disturbing your delicate microbiome. It’s the future of clean, powered by biotech—available now. 

Take your scalp and haircare routine to the next level with AirWash™.


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your healthy scalp essentials

AirWash™ dry shampoo
Rated 4.5 out of 5
Based on 375 reviews
Revolutionary dry shampoo reduces oil + odor—weightlessly.
PEPTIDE PREP™ detox shampoo
Rated 4.8 out of 5
Based on 309 reviews
Color-safe, non-stripping clarifying shampoo with the K18PEPTIDE™
DAMAGE SHIELD pH protective shampoo
Rated 4.6 out of 5
Based on 299 reviews
Color-safe protective shampoo maintains hair health + strength
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