What’s the ideal frequency for washing your hair?

Your sebaceous glands have been with you since birth. They developed during your fourth month in the womb and are most densely located on your scalp and face, though they cover your entire body except for the palms of your hands and the soles of your feet.

These glands are typically linked to hair follicles (except in hairless areas like your eyelids and lips, where they function independently). Now that you understand their origin, you might wonder about their purpose. Sebaceous glands produce sebum, the natural oils that keep your skin and hair hydrated and protected. Specialized secretory cells in the skin’s dermal layer absorb fats and break down within the gland, transforming into sebum. This sebum is then released into the hair follicle’s shaft and eventually reaches the skin’s surface, the stratum corneum. Essentially, your body releases these fats and cellular remnants onto your skin and hair.

It’s no surprise we rely on shampoo.

While it might sound unpleasant, sebum plays a crucial role. As we’ve learned, it helps waterproof and hydrate your skin and hair. Without it, your skin can dry out and shed too early, leaving vulnerable cells exposed. But isn’t letting sebum build up the same as being oily and unclean? In modern Western society, the answer is yes.

Our bathing and hair care habits revolve around a peculiar cycle: stripping away natural oils with soap and shampoo, then restoring them with moisturizers and conditioners. This daily routine persists for a couple of reasons. First, oily, unwashed hair is generally frowned upon in Western culture—and skipping showers for more than a couple of days just feels uncomfortable. Second, excess sebum can contribute to skin issues like acne vulgaris, where it clogs hair follicles, creating a breeding ground for bacteria. These bacteria break down fats into fatty acids, triggering allergic reactions that manifest as acne.

For more insights on hair washing, check out Hair Washing: Fast Facts.

With both pros and cons to washing and not washing your hair, finding the right balance is key. So, how frequently should you shampoo your hair?

To Shampoo or Not to Shampoo?

If you aim to stay socially acceptable and odor-free, you’re on the right track. But how does this affect your hair-washing routine? How frequently should you cleanse your hair?

The answer largely depends on personal choice. Even among experts like dermatologists and trichologists, opinions vary on the necessity of shampooing and its ideal frequency. Some argue against frequent use, claiming it triggers excess sebum production to counteract its removal [source: Aubrey]. Others insist shampooing is essential to prevent sebum buildup in pores and hair follicles, which can cause skin issues like acne [source: Grossman].

Daily shampooing at home is a modern practice. In the 1950s, women typically visited hairdressers weekly for washing and styling. This routine worked well, and the trend has recently revived, with many salons noting clients switching to weekly rather than daily shampooing [source: Grossman].

At the start of the 20th century, women often waited a month between salon appointments. However, a 1908 New York Times advice column marked a shift, suggesting bi-weekly shampooing was perfectly fine [source: Aubrey].

Some have extended the time between shampoos even further. An accidental experiment began in 2007 when an Australian radio guest mentioned he hadn’t shampooed in ten years. Listeners responded, leading to a six-week challenge with 500 participants. After six weeks without shampoo, 86 percent reported their hair was unchanged or improved compared to regular shampoo use [source: Lacko].

Alternative methods are also used to maintain clean hair. Dry powder products, which absorb excess oils, can be blotted with cheesecloth and combed out [source: Grossman]. Baking soda, combined with a raw egg and a lemon juice rinse, offers a natural hair-cleaning solution [source: Siegle].