A new trend in beauty is based on the idea that less is more - at least when it comes to shampooing your hair.
Some people - including celebrity Kim Kardashian - have stopped shampooing their hair regularly, or even altogether, based on the belief that the detergents in shampoo strip hair of its healthy natural oils. This form of hair care has even been dubbed "no-poo."
Kardashian recently revealed that she washes her hair only every five days.
But is this truly healthy for your hair and scalp?
That largely depends on the type of head you have, according to skin and hair experts.
"It's not a one-size-fits-all situation," said Dr. Angela Lamb, director of Westside Mount Sinai Dermatology in New York City. "It all depends on your hair type. There are some hair types that would tolerate it better than others."
"No-poo" proponents clean their hair and scalp with products that contain no detergent, Lamb said. Alternatives run the gamut from a home-brewed concoction containing baking soda and apple cider vinegar to a variety of new manufactured products offered through salons that contain natural oils and non-detergent cleansers.
"There are a couple of salons in New York that are pushing it," Lamb said. "Once I start hearing about it in my office, I know it has some type of following."
Hair is made of protein, and at the root of every hair is an oil gland, Lamb said. The oil produced by this gland coats the hair and protects it from becoming brittle.
The thought behind the "no-poo" movement is that "by leaving the natural oils on the hair, the hair doesn't need any styling products," said Dr. Lisa Donofrio, an associate clinical professor of dermatology at Yale University School of Medicine. "If you don't apply any styling products, then there is no need to wash your hair. No products, no need to wash them out."
Hair products like gel, mousse or hair spray are one reason why people need to wash their hair regularly, Lamb said. "You don't want to leave products in for a month," she said. "Those are things you want to wash out, or the hair can become brittle and break."
However, there are other reasons why people need to use a detergent shampoo on a regular basis, some health care experts contend.
For example, the scalp beneath the hair needs to be regularly cleaned of oil, dried sweat, dirt and dead skin cells, said Dr. Robert Dorin, a board-certified hair transplantation surgeon in New York City.
Those using "no-poo" products "aren't really cleaning their scalp," he said. "They're not taking off the environmental impurities."
People who don't use detergent shampoo to clean the scalp run the risk of developing fungal and bacterial infections, Dorin said.
They also might suffer from irritation of the scalp, flaking and pimple-like lesions, Donofrio said.
Lamb added that regular shampooing also helps control and treat scalp problems, such as psoriasis, eczema and dandruff.
Still, there's no hard-and-fast rule for how often to wash your hair with a detergent shampoo, the dermatologists agreed.
Lamb said that everyone is different, and the only way to know how often you should wash your hair is to experiment.
"You're not putting your hair at risk by trying this," she said. "Try it and see. Frankly, I have some patients who love it, and say their hair is the healthiest it's ever been. And I have other patients who say their hair has too much build-up; their scalp is too oily; their scalp is itching."
Donofrio agreed. "Bottom line: if you feel the need to join the no-shampoo movement, your hair will tell you if it works for you."