Going a long time without washing your hair can cause a buildup of a yeast-like fungus called Malassezia on your scalp. Over time, this leads to a layer of dead skin cells that shed from your head in the form of oily, yellow-ish dandruff flakes. Dandruff can also make your scalp red, scaly, and itchy.
Prolonged periods of not washing can cause cause buildup on the scalp, damaging hair and even impeding its ability to grow, Lamb said. Grime from dirt, oil and hair product can show up within four to six days for people with finer, straighter hair.
"The average individual can typically go 2 to 3 days without shampooing their hair. However, if your hair is visibly oily, you may not want to wait that long," she says. "Usually, you can go longer without washing your hair when your hair is styled up, but no one should ever go more than 14 days."
When one has extremely dry hair which is not washed often, it can lose its natural moisture with age. According to stylist Rosi Fernandez, director of Ananda Ferdi it is not advisable to go for more than a week without washing hair, as follicles become clogged and do not get oxygenated," she explains.
Not washing your hair regularly can make the scalp flaky and lead to dandruff. It will make you feel itchy and you can also get rashes on your scalp. “You can develop major dandruff problem if you don't wash your hair for 1 or 2 weeks,” she warned.
Not washing your hair enough can lead to dandruff, irritation, clogged pores, breakouts, and even hair loss over time, says Dr. Rubin, explaining that these issues are usually the result of buildup and residue from sebum, hair products, and dead skin cells.
As with many hair care trends, certain hair types may see better water-only hair washing results than others. According to McDaniel, water-only washing “works best on thick, coarse, curly/coily textures or those that tend to experience dry scalp or hair.”
Washing your hair only once a week brings the benefits of natural oils into sharp relief. After all, many hair serums and treatments are meant to replicate the oils produced by the scalp, but excessive shampooing strips the hair of these valuable substances.
"You can use dry shampoo to lengthen the time in between washes, to absorb sweat after workouts or to just refresh hair for a 'fresh-styled look' without the hassle of getting hair wet and blow drying it."
There's also your everyday body odor, sweat, and bacteria that fester in your hair. Left untreated, it can start to smell sour or mildewy, especially if you have thick hair which traps odors more easily. The longer you go without washing, the worse the stench gets.
A clean, healthy scalp promotes hair growth. The bottom line is that dirty hair does not grow faster than clean hair, so you might as well have a clean scalp and fresh hair. Your hair will look better, feel better, and be healthier as a result.
"With more natural oils lubricating the hair [from water-only washing], the hair shafts glide over each other, leading to less tangles." Skipping shampoo also allows for the hair's sebum to distribute throughout, and this may make hair appear more shiny and less frizzy.
Dr. Fusco says that this can lead to scalp inflammation, dandruff, excess shedding, and even folliculitis, which are tiny pimples on the scalp. "When we don't wash often enough, the hair follicle beneath the surface can be suffocated to a degree leading to less than optimum new hair growth," says Abney.
Not washing the hair regularly with shampoo has certain advantages like cost and time saving, reduced exposure to chemicals, and less risk of hair damage. However, it may increase the risk of scalp irritation and infections due to the buildup of sebum, dirt, and sweat.
Narrator: After six months to a year, all that gunk can clog up your hair follicles, which can prevent new hair from growing and, over time, ultimately lead to hair thinning or even hair loss. There's also a risk of your scalp getting infected from all the bacterial buildup.
When to wash. Rossi generally tells his patients they should wash their hair once or twice per week. But if you've had chemical treatments that can make your hair drier — such as bleach, perms or relaxers — you might want to wash it less than once weekly to avoid breaking or brittle hair or split ends, he said.
“There are too many variables to set one rule,” Jessica J. Krant, a cosmetic and medical dermatologist at the Laser & Skin Surgery Center of New York said in an interview. “I believe hair can be washed anywhere from daily to once every two weeks, depending on hair and skin type, hairstyle and lifestyle.”
Many doctors say a daily shower is fine for most people. (More than that could start to cause skin problems.) But for many people, two to three times a week is enough and may be even better to maintain good health.
If you use styling products like mousse, hair spray and dry shampoo regularly, the no-poo method might make it hard to fully cleanse your hair and scalp of product build-up. Over time this can impact hair and scalp health.
You can also use only water to wash your hair. This method works best for people with curly, thick, coily and coarse hair. Also, if you have tangle-prone hair, you can choose to clean your hair only with water and then go for a deep conditioner.
The folks who don't wash their hair for months on end claim that when they stop washing, their hair eventually produces less scalp oil, which is called sebum. The result: hair that's shiny, moist and healthy ' never greasy.
But there is zero scientific evidence to cement that washing it less makes it grow faster (sob). However, excessive shampooing (basically more than your hair type needs) can cause dehydration and lead to breakage, so overzealous shampoo-ers should err on the side of caution.
Wash to suit your needs and your hair type. Oily and fine or thin hair types should wash every one to two days. This schedule allows for removing buildup and the natural oils to stimulate hair health and growth. Wavy or curly hair and dry or damaged hair types should wash in the range of once every four to seven days.