A viral TikTok showed the 'disgusting' results of a dirty hairbrush which can be a 'breeding ground' for bacteria and build-up, according to experts

• A viral TikTok video by everything_tidy showed the 'disgusting' results of a dirty hairbrush.
• The video suggested one reason hair gets oily or greasy is due to an unclean hairbrush.

A woman's viral TikTok video showed just how much dirt could fester on unwashed hairbrushes, sparking a wave of discussions about hair and scalp health.

After being inspired by a TikTok video made by unitfour4, where they suggested that oily hair is caused by dirty brushes, a user named everything_tidy decided to test the theory.

"I've put all my brushes in the sink and we're going to leave them for a bit. I've used hot water and shampoo because she didn't state what she used – I figured because it's hair," she said in the video, which has more than 4.3 million views.

After an hour, the woman returned to the sink to find the water a "disgusting" murky brown color.

"Ladies, don't forget to wash your hairbrushes," she said. "I didn't even know that was a thing."

Experts told Insider that dirt build-up on hairbrushes can affect scalp and hair health

According to Bridgette Hill, a certified trichologist and hair science expert known as "The Scalp Therapist," dirty hairbrushes are a "breeding ground for dust, bacteria, mites, and product build-up."

"Contemplate on how frequently you 'cleanse' the hair and reintroduce the same dirty hairbrush to your scalp and hair fiber," Hill told Insider. "It is as if you are recontaminating the environment that was just cleansed."

Hill, who founded Root Cause Scalp Analysis, added that using an unwashed hairbrush can negatively impact sebum, the scalp and hair's natural moisturizer produced by sebaceous glands.

"Brushing assists with distributing sebum," she said. "Uncleansed and unsanitized brushes spread bacteria, recontaminate the scalp and hair with old product build-up, spread yeast and bacteria to the base of the hair fiber, leading to congestion and inflammation which exacerbates any unwanted scalp symptoms and conditions."

Unwashed hairbrushes can also lead to "chronic inflammation, irritation, and possible infection," Hill continued.

People should wash their hairbrushes at least once a month using these 6 steps, experts say

Michele Pritchard, owner, and founder of Michele Pritchard Hair shared a video in November 2020 showing her 216,900 TikTok followers how to properly clean a brush.

"Use your shampoo to clean them," Pritchard told Insider. "I recommend applying a small amount on a soft toothbrush and scrub using water."

She said the first step for a proper clean is to remove the loose hair from the brush while it's dry before filling a bowl or sink with water. Pritchard said in her TikTok video that she prefers to use a pintail comb. Then, dip a small toothbrush into the water and apply a "pea-size" amount of shampoo to the toothbrush.

Next, "scrub the hairbrush with a toothbrush," but don't soak your hairbrushes in water, Pritchard said. "You could ruin the handle and head of your brush if you soak them as the water may not dry out all the way!" she continued.

After scrubbing, rinse the toothbrush and then use it to ensure all the shampoo has been removed from the brush.

Finally, Pritchard said to lay the clean hairbrush on a towel to dry.

"Invert them, so the handle of the brush is at an incline," Pritchard said. "This will help [the] brush dry out more evenly and water does not sit on the handle."