But there's a growing number of hippies naturalists out there promoting the no 'poo movement, or the belief that you don't need to wash hair at all.
Like, ever. Is this foul? Yes, but it won't kill you.
To the no 'poo-er's credit, shampoo can contain some questionable ingredients (like formaldehyde, a potential carcinogen, and sulfates, those foaming agents that can dry out hair and skin).
It's a fairly modern invention, too, considering the first commercially available shampoos hit shelves around the turn of the twentieth century. (This is when people started dabbling with things like deodorant and toothpaste, too, thanks to the introduction of modern advertising.)
But dermatologists warn that opting out of shampoo altogether could make your scalp a breeding ground for bacteria and lead to dandruff.
Look for a happy medium and shampoo a few times a week, but don't give it up entirely, says hairstylist Ken Paves, who's tended to the strands of celebrities like Tom Brady and David Beckham. And if the thought of your mane going a week unwashed gives you hives, consider some of Paves tips for adjusting to a life less clean.
Avoid Greasy Hair Culprits
Skip heavy, hydrating hair products (look for the word silicone) because they'll make hair feel oily and flat. Same goes for constantly running your fingers through it, or letting the wind whip locks around. (Both of these spread the oil that's sitting at roots throughout your head, so keep your hands off and throw on a hat during super blustery days.)
Push Through the Feeling
"Hair definitely adapts to not washing it," says Paves. When you remove oil from your hair, your sebaceous glands compensate by producing more oil. So the less often you shampoo, the less oil your hair will produce. The first few weeks of cutting back might feel a bit gnarly, but your hair should acclimate about a month in.
Rinse With Water
"Rain has eroded mountains. Water alone will get rid of some sweat and styling products," says Paves. "Rinse your hair really good with warm water, massaging your scalp to lift any oils and product, then rinse." You can follow with conditioner if that clean smell triggers happy thoughts.
Discover Dry Shampoo
For a quick pick-me-up between washes, try rubbing a dry shampoo into your roots. (If you haven't tried the stuff or seen it in your girlfriend's bathroom, dry shampoo is usually a mix of absorbing agents and fragrance that sucks up grease from your hair and scalp). "It's a great way to freshen hair, absorb oil and create volume," says Paves. Baby powder or cocoa powder (for dark hair) do the job well, too.
More From GQ:
Dave Chappelle Is Back (This Time We're 100% Sure It's Maybe Totally for Real)
Totally Transform Your Sleep in Just 7 Days