The study, published in the American Academy of Pediatrics journal on June 9, found that some TikTok videos promoting certain skin care routines put teenagers at risk of lifelong skin allergy.
Northwestern Medicine dermatologist and study author Author Molly Hales said girls ages 7 to 18 are using an average of six different products on their faces.
"We found significant dermatological risks associated with these regimes, including a very high risk of irritation," she said. "This high-risk of irritation came from using multiple active ingredients at the same time as well as applying the same active ingredient unknowingly over and over again."
In one video included in the study, for example, the content creator applied 10 products on her face in six minutes.
Hales said many of the ingredients found in these products carry a high risk of skin allergy and leave out the most important products, such as sunscreen.
"Once you develop a skin allergy to a particular ingredient can actually endure for the rest of your life and limit the kinds of products you can apply," she said.
She said many of the regimens also emphasized "lighter, brighter skin," which could lead to consequences beyond skin damage.
"These videos reflect and may amplify unattainable standards of beauty and age bias," Hales said.
The study also found that each teen daily skin care regimen costs an average of $168, and researchers estimate that many of these products only last about a month, depending on the size of the them.
"I think there also were real associations between use of these regimens and consumerism," said Northwestern adjunct professor and study author Tara Lagu. "There's a desire to have more products and more expensive products in a way that for 7 to 14 year olds feels really problematic."
And while parents may monitor their kids' social media use, Hales and Lagu said because of the way TikTok's algorithm works, it's nearly impossible for them to track exactly what children or adolescents are viewing.