Tween and teen girls are posting skin care videos made popular on social media. Some feature girls demonstrating multistep skin care regimens that include anti-aging products.

These skin care videos on TikTok may do more harm than good, a team of researchers at Northwestern University found.

“We looked at TikTok because that was the Ground Zero of where these girls were finding and promoting skin care products and regimens,” Molly Hales, corresponding author on the study, told TheDoctor.

The content creators of the skin care videos popular among teens and tweens were between seven and 18 years old.

Hales and a colleague each created a new TikTok account and claimed to be 13 years old. The researchers reviewed 100 Get Ready With Me or GRWM videos with about one million views each. The skin care regimens included an average of six different products. The content creators of the videos they viewed were between seven and 18 years old.

“The TikToks I came across featured 10- or 11-year-old girls with beautiful, young skin applying sometimes a dozen or more products one after the other,” said Hales, a postdoctoral fellow and dermatologist at Northwestern University Feinberg School of Medicine.

Hales was surprised that the regimens were so extensive because, as a dermatologist, she would at most suggest people use about three products; and she is careful to explain when and how often they should be used.

In contrast, the 25 most-viewed videos featured a regimen with an average of 11 active ingredients. Because the same active ingredients were sometimes found in several different products, they were often applied many more times than was recommended.

The most common active ingredients were alpha-hydroxy acids, including lactic acid, citric acid and glycolic acid, and beta-hydroxy acid, or salicylic acid. When used in low concentrations, alpha-hydroxy acids have a gentle exfoliating effect, Hales explained. Alpha-hydroxy acids are potentially irritating, however, so a product containing an alpha-hydroxy acid should be applied no more than once a day.

Alpha-hydroxy acids increase sun sensitivity and the risk of sunburn and skin cancer. The U.S. Food and Drug Administration recommends that people using products with alpha-hydroxy acids use sun protection, including a sunscreen. Only 26 percent of the regimens Hales and her colleague viewed on TikTok included a sunscreen.

Vitamin-based ingredients like vitamin E, often listed as tocopherol on the ingredients list, were also common. They can be irritating to the skin too, according to Hales. Hyaluronic acid, which was originally developed to plump up the skin, was a common ingredient as well.

For girls who don't have a diagnosable skin condition such as eczema or acne, Hales recommends using a gentle cleanser, ideally one that is fragrance free, once or twice a day and a fragrance-free, mineral-based sunscreen daily in the morning.

The videos emphasized the ideal of having “glowy” skin, leading Hales to think about what it means for something to glow. Something that glows is bright, illuminated and a little shiny, but it tends to also be lighter, setting up an unwitting bias.

“These regimens may be promoting a standard of beauty that excludes girls with darker skin,” Hales said. She hopes to do a similar study with creators with darker skin to see what standards of beauty and what products are being promoted in their videosto explore this possibility.

For girls who don't have a diagnosable skin condition such as eczema or acne, Hales recommends using a gentle cleanser, ideally one that is fragrance free, once or twice a day and a fragrance-free, mineral-based sunscreen daily in the morning.

The skin care regimens on TikTok aren't cheap. Hales points out that a cleanser such as Cetaphil and a mineral-based sunscreen from the drugstore cost about $20, while the regimens promoted online cost an average of $168.

The study is published in Pediatrics.