Sweat happens to everyone. While stringy bangs are often worth the endorphins from a hard workout or the bliss of taking a scenic hike through the desert, it’s important to understand what it’s doing for our bodies—and to our hair.

what’s the purpose of sweat?

The primary function of those salty droplets is to regulate body temperature (making it possible for you to stay upright during that claw clip-melting hot yoga class). 

Beyond its ability to cool us down, sweat contains antimicrobial peptides, which help to defend against harmful microbes and balance the scalp microbiome. 

In short: sweat is incredibly important to our bodies, but it can have a negative impact on your scalp and hair health if left unchecked.

how does sweat affect scalp + hair health?

“Sweat plays a complex role in scalp health,” says Karis Stanley, K18 Director of Product Development, Innovation + Compliance. “It delivers beneficial Natural Moisturizing Factors (NMFs), such as lactate and urea, which support hydration and barrier function.” 

The scalp knows how to handle sweat and actually needs it to support our microbiome (the system that regulates sebum production and protects our delicate little hair follicles).

However, hair can trap sweat, preventing normal evaporation and creating a warm, moist environment that sometimes encourages an imbalance in the scalp microbiome. “Markedly, in the growth of Malassezia (a yeast-like fungus), a known contributor in seborrheic dermatitis and dandruff,” says Stanley. This fungus is often the cause of irritation and itching. 

Sweat on its own often doesn’t smell bad, but when it is left on the scalp, you might start to notice an issue. “The breakdown of sweat both by external aggressors and the microbiome can also produce Volatile Organic Compounds (VOCs) resulting in scalp odor.” 

The lesson? When you let sweat + dirt sit on your head for long periods of time, your hair and scalp health can suffer. 

is that why you shouldn’t leave sweat in your hair after working out?

As sweat evaporates, it leaves behind salts and metabolic waste that can irritate the scalp and dry out your hair. Making time for an “Everything Shower” isn’t always easy—but we used biotech to create a solution. 

Instead of leaving sweat sitting on your scalp (and risking the state of your microbiome), AirWash™ dry shampoo instantly absorbs sweat + oil and eliminates odors.

are sweaty hair and dirty hair the same thing?

Not really! “Sweaty hair comes from the scalp’s physiological response to heat, exercise, or stress, and produces the “wet” look at the roots,” says Stanley. “Dirty hair can be caused by actual dirt, pollution, smoke, and other elements that can attach to the hair strand, leaving it feeling weighed down, limp, dull, and unmanageable.” 

Sweat combined with factors like pollution and UV rays, and  mixed with sebum, can contribute to oxidative stress on the hair. 

Thankfully, AirWash™ tackles sweat, oil, and odor all at the same time.