Ask a woman “how often do you wash your hair?” and you’ll get a different answer every time.
There are no straight answers to this perennially thorny beauty issue.
Some people will swear by a daily lather, while others insist one or twice a week is sufficient. Certain renegade types have turned their backs on their entire concept, giving rise to the No ‘Poo movement.
The truth is, how frequently you shampoo depends on a wide myriad of factors, whether that’s hair texture, scalp condition or whereabouts you live.
In an attempt to cut through the bluster and separate fact from myth, we sound out some expert opinion on the matter.
From leading trichologists to medical researchers, dermatologists and world-renowned stylists, come hear what the pros have to say about all things hair washing...
All in the texture
Hair texture and density are crucial when it comes to deciding how often you should wash your hair.
In general, thicker hair takes longer to get oily because of the sheer amount of it.
“It’s quite common for people with thick hair to wash their hair only once or twice per week,” says Daiva Valioniene, a senior hair specialist nurse at the Belgravia Centre, London.
Curly hair also tends to require less frequent washing. “I compare thick, curly hair to denim,” says New York-based hair artist Abraham Sprinkle. “Denim seems to feel best a couple of days after wearing, and this holds true for curly hair.”
“The curlier your hair is, the longer you can go between washes,” explains dermatologist Dr. Doris Day. “The straighter it is, the faster the oil wicks down, so that can make it oilier faster. If you have superstraight hair, you may not be able to go more than two days without washing.”
However, most stylists agree that while fine hair may require washing around three times a week, daily shampooing would only be called for if you have very fine hair.
On the other hand, if you’re the owner of porous, coarse hair that dries almost immediately after you shower, washing less often is recommended.
“It should be shampooed no more than twice a week as it’s capable of soaking up large amounts of water which weighs down each strand, resulting in loss of elasticity and leading to breakage,” says Leonora Doclis, trichologist and a colleague of Valioniene’s at The Belgravia Centre.
A question of scalp
Perhaps more important than texture in determining how frequently you should head for a lather is the condition of your scalp, and how active it is in producing oil.
“If you have oily scalp, then daily washing is needed,” says Carolyn Goh, MD, assistant clinical professor at UCLA. “Sometimes, people think they have dry scalp because they have dandruff, but in those situations, more frequent washing is also helpful.”
Valioniene agrees. “People who have scalp conditions, from mild dandruff to Psoriasis or Seborrhoeic Dermatitis, would be advised to wash their hair more often due to faster than normal build-up of dandruff,” she says.
“Frequent shampooing, even daily, is recommended if you have a flaky scalp to get rid of dead skin cells as they may cause problems with the production of natural scalp oils,” says Doclis.
“If you have a healthy scalp with hair that gets oily, wait two days before washing.”
Hot weather and the gym effect
How frequently you need to wash your hair also depends on your lifestyle choices. If you run 10k every day, for example, you’ll likely clean your hair daily as part of that routine.
But even here, shampoo isn’t a necessity. Hair stylist Kerrie Urban says that if you want to avoid doing a full wash, consider a water-only rinse after workouts. This will remove salt and sweat just as effectively and you can save the shampoo for your “normal” washes instead.
Climate also dictates how often hair should be cleansed.
You’ll likely need to run it under a shower more in tropical destinations or during hot, humid summer days. These kind of conditions build up sweat on the scalp and accelerate the formation of lank roots.
In dry winter seasons, however, you’ll notice that your hair will usually last a few days longer without demanding a wash.
Delicate, post-treatment hair
If your hair has recently undergone treatment such as keratin, chemical straightening or relaxing, you should consider washing it a bit less frequently in the short-term, to reduce the stress it’s under.
“I put this in a delicate category, like lace or hand-washables – the least amount you have to alter its pH, the better, as it's more vulnerable when wet,” says Sprinkle. He recommends washing once a week in these circumstances, using a gentle rinse.
But if you’re going to use heat straightening tools or do a DIY blow-dry, make sure your hair is completely clean to begin with every time. “Hair will last longer, look better, and you’ll need to use those stressors less often overall,” says hair stylist Alli Webb, founder of Drybar.
The strip myth
Contrary to common belief, shampooing your hair every day won’t get rid of its natural oils.
“It is often thought that frequent shampooing ‘dries out the hair's natural oils,” the experts at Philip Kingsley say.
“However, quite the contrary! Shampooing, if done correctly and with the right products, actually remoisturizes. The natural oils produced by your scalp simply sit on top of your hair shaft and do not penetrate it.”
Trichologist Iain Sallis agrees.
“You can quite happily shampoo your hair daily and not worry about the effects of the detergent upon it,” he says.
“Your main problem would be from styling your hair every day, if you use heated appliances on your hair such as straightening irons every day, this could seriously damage your hair, not the shampooing bit.”
Shampooing daily won’t make your hair more greasy, either: oiliness is more likely to be influenced by factors such as hormones and stress.
“Washing your hair every day with a quality shampoo invigorates the scalp and leaves the hair healthy and shiny,” says trichologist Vanessa Bailey.
A happy medium
While dousing your hair every day won’t strip it of oils, it’s worth bearing in mind that it will dull colouring more quickly and may cause build-up of the water’s hard mineral deposits.
As wet hair is more sensitive, washing it a lot will leave it more prone to breakages, too.
It’s worth considering the role of dry shampoo here.
"Use dry shampoo instead of washing your hair every day. It will help reduce the oil build up in your hair and gives amazing texture," says stylist Mark Townsend, who tends to Reese Witherspoon's hair. "You can also leave dry shampoo in (instead of brushing it out) to give volume."
"As opposed to washing your hair every day, dry shampoo will help to refresh your hair at the roots and the tips," agrees hair visionary Luke Hersheson of the Hershesons empire.
When to call time
On the other end of the scale, experts are agreed that simply not washing your hair isn’t the way forward – no matter what its texture.
Instead of regenerating its own oils after a certain period, “it will just get dirtier and could result in an irritated, itchy scalp and greasy, lank hair,” says Bailey.
“Regardless of how your hair feels, don’t go longer than 14 days [without washing], ever,” warns Angela Lamb, assistant professor of dermatology at Mount Sinai in New York City.
Ultimately, shampooing is about cleaning your scalp rather than your hair per se.
So, in deciding how often to wash it, you should use your scalp condition as a guide.
“If you start to have buildup on your scalp – if your scalp starts to get itchy or there's irritation – then you're not washing enough,” says celebrity stylist Marc Mena.
Roots are a good visual indicator here.
“If it looks slightly oily at the roots, leave it for a day, but if it starts to look very lank at the roots, wash it,” says Doclis.