According to dermatologists and hairstylists alike, when shampooing your hair, you are actually cleaning your scalp and not strictly your locks. It follows, then, that when considering whether to double or even triple shampoo your hair (after all, the label often says “rinse and repeat”), what you are truly contemplating is whether you should engage in a deep scalp cleanse. How necessary is that practice when it comes to scalp health?
Overall, experts seem to agree that a single wash will clean the majority of folks’ scalps properly — therefore resulting in thicker, lusher and less flaky hair — but there are times when multiple shampoos might be beneficial.
What shampoo does to your scalp
“The scalp is a very salacious and oily part of our skin and there is a very special microenvironment there, so we need to wash the skin of the scalp to remove dirt, debris and oil,” explained board-certified dermatologist Dr. Mia Jing Gao. “Because it’s an oily area, you also get a lot of yeast growth, so it’s important to keep it clean to prevent things like spots on your scalp and eczema.”
Shu-Lan Cheung, a hair salon owner based in the United Kingdom, likens shampoo to detergent.
“It removes dirt and odour from both the scalp and the hair strands themselves,” she said. “Depending on the formula, it can add or take away things. For example, it can help limit oil or boost and lock hydration.”
She also noted that, given that a proper wash stimulates the scalp, the practice promotes hair growth, as was made evident in a 2016 study in which regular, standardised scalp massages resulted in increased hair thickness by “inducing stretching forces to dermal papilla cells in the subcutaneous tissue.”
When shampooing your hair twice, then, you’re effectively trying to clean out the scalp more thoroughly. It turns out, though, that most experts advise you don’t do that in the majority of cases.
The pros and cons of double shampooing your hair
“Generally, if you’re using a good-quality shampoo, you will only need to shampoo your hair once,” Cheung said, specifically mentioning that the guidelines don’t change based on gender or length of hair. “If you’re washing your hair less frequently or using multiple styling products, you may need to think about double washing because the first wash loosens the dirt and the second removes it.”
Should some people, perhaps, consider applying the product a third time? “Triple shampooing is, in most cases, unnecessary,” Cheung said. “Except when hair is exceptionally waxy or greasy from exercise.”
According to board-certified dermatologist Dr. Leah Ansell, even two washes are unnecessary for most people, because the practice may end up stripping your hair of some beneficial oils.
“The key is keeping good oils on your scalp, so overwashing might dry them out too much and lead to more problems,” she explained. “It is much better to wash once with a high-quality shampoo than multiple times with a subpar one.”
Overwashing may lead to a slew of other issues, including colour stripping, dryness, split ends and flakiness.
“Hair texture is a large factor, too,” Cheung said. “For instance, curly hair may become frizzy if it’s washed too frequently.”
As a general guideline, you should assume that if your head feels itchy, flaky or even sore, you might be scrubbing your scalp a bit too often.
“It’s like washing any part of your skin,” Gao said. “When you overwash your hand, for example, you get eczema because every time you do it, even if you’re just wetting your skin, you’re disrupting the barrier so you get dryness, irritation and redness.”
All that being said, there are two instances when using shampoo twice during one “washing session” may prove to be fruitful: if exercising often or if using a medicated shampoo.
“If you exercise a lot, you get buildup on your scalp so you might want to double cleanse,” noted Gao, mentioning that folks who use medicated or antifungal shampoos might choose to rinse off the product a second time using a “regular” shampoo because “the former might not thoroughly remove the oiliness.”
Overall, it’s important to thoroughly wash the scalp with shampoo to promote hair growth, but it’s just as paramount not to over-cleanse the area — a practice that can cause other related problems.
It all leads to two questions: What’s the proper way to wash hair and how often should we be doing it?
A step-by-step guide to shampooing your hair
Hairstylists and skin experts agree there is a specific way to properly wash your hair, starting with thoroughly wetting the area.
After selecting the correct shampoo for your hair type, apply some to your roots and start massaging thoroughly but gently. Proceed by sliding the product down the hair shaft in one direction, quite literally removing the shampoo from your locks while positioning your head under the water.
As for how many times a week you should engage in the practice, it depends, although you should aim for two to three washes a week.
“The short answer is that everyone’s hair is unique,” Cheung said. “The production of hair oil in specific is influenced by our hormone levels and may affect how we approach hair washing routines.”
For example, noted the expert, those with high levels of androgens may have to deal with more hair oil, and therefore may need more frequent washing, than those boasting lower levels of it.
“We also all have different tolerances or ways to style oily or greasy hair,” she said. “Understanding your hair’s specific needs can help you choose the best products and develop a customised routine that works in the long run.”
Gao agreed that the number of weekly washes varies based on a number of factors but said, “On average, three times a week should work.”