Beauty Advent calendars have become so popular with teens and tweens that even Alicia Tennenbaum’s 8-year-old is asking for one. Tennenbaum, a Brooklyn mother of three daughters, is currently on the hunt for versions that satisfy the varying demands of her children’s wish lists.

Growing up in New Jersey, Tennenbaum was used to Advent calendars with tiny toys or squares of chocolate hidden behind colorful cardboard doors, counting down to Christmas. In recent years, she’s watched one of her favorite holiday traditions snowball into an avalanche of luxury beauty doodads. Her middle child, age 12, is lobbying for a lotion- and lip-balm-packed calendar from influencer favorite Evolution of Smooth (EOS). The choo choo train-shaped calendar appears in TikToks by popular content creators and beauty editors but isn’t for sale to normies.

“I understand the appeal of getting a nice surprise every day,” Tennenbaum tells Yahoo. “But what used to be a nice tradition has spun completely out of control.” On top of the hefty cost, she added, there’s the stress: “These things sell out fast, so that’s another added pressure.”

Even if it’s too late for Tennenbaum to get ahold of the EOS calendar, there’s no shortage of other options.

From Ulta Beauty and Sephora’s special holiday mixes of house-favorite brands to a showstopper from cult British brand Charlotte Tilbury (a gilded “treasure chest” with seven miniatures and five regular-size items — and a $220 price tag), the market is awash with seasonal specials that are at the tippy-top of countless young beauty fanatics’ lists.

“Advent calendars have always been a way for my family to stretch out the holidays,” says Brad Dobbin, a father of three daughters and a software developer in St. John's, Newfoundland. This year, he let his daughters choose their own calendars. The younger two selected Charlotte Tilbury, and the oldest will be ripping apart Sephora’s set. (Dobbin bought his wife the $245 “24 mystery must-haves” Advent calendar from MAC.) “When they were younger and they’d get Lego calendars, I’d get into it too,” Dobbin says. “Now that they want beauty ones, I just sit back and watch wars break out over who gets to use the face mask or the mascara. It’s one way to keep the holiday spirit alive, I guess.”

The allure isn’t hard to grasp. Packed with items that are secreted away behind cardboard panels, a beauty Advent calendar hits the sweet spot in the age of unboxing videos and #GetReadyWithMe TikToks. Brands benefit in multiple ways too. In addition to the high profit margins, putting new products into consumers’ hands is a way to market the formulations they hope people will keep coming back for.

The so-called Sephora kids, as the segment of young serum-obsessed shoppers is known, aren’t just the next generation of beauty buyers. Their cosmetic bags are already brimming with the latest bronzers and oils. According to data from consumer research firm NielsenIQ, households with children aged 7 to 12 spent close to $2.5 billion on skin care last year, up from $1.8 billion in 2022. They’re not just copying older influencers. A recent study in the journal Pediatrics revealed that 31% of content creators making skin care videos are under the age of 13 — and the videos had an average of 11 potentially irritating active ingredients (the most common one: citric acid).

No wonder the aisles of drugstores and cosmetics emporiums have begun to resemble the shelves of candy stores, with fruit-colored packaging and playful product names that often gloss over the formulations’ heavy-grade ingredients that aren’t considered safe for young skin, such as retinol and acids. Amid the loudening cries from parents expressing safety concerns regarding children’s use of products aimed at older customers, California Democratic Assembly member Alex Lee introduced a bill that calls for age-verification flags to pop up at the register or online, in order to stanch the tide of young customers purchasing products with harsh ingredients.

In the meantime, savvy brands are having a field day with what is fast becoming an entrenched holiday tradition. Amazon put out its own Advent calendar with miniatures from tween favorites like Touchland and Laneige for $98. Anthropologie’s 24-day box, also priced at $98, was sold out the week before Thanksgiving.

With “mystery” being a key aspect of many of the big-ticket beauty offerings, it’s not always easy to verify that the contents are kid-safe. Laura, the creator behind the parenting-centered social media account @MomLifeWithLaura, turned her children’s cries for Advent calendars into a challenge. She purchased reusable calendars made of wood and hand-selects the goodies that she packs for her son and beauty-obsessed daughter. “For my daughter, it’s mainly beauty things like lip balms, and I avoid anything with retinol,” says Laura, who has 1.8 million followers on TikTok and doesn’t share her last name or location for privacy concerns.

In prior years, when she let the companies do the choosing and packing, Laura watched as her kids evaluated each day’s offering. For every item that made the grade, especially with her daughter, there was a castoff. “This time, I’m throwing in other items like the miniature Odwalla bottle I found that exactly matches the one my daughter takes everywhere,” she says. “This way, you can be more thoughtful about it.”