Flavored gummies are the new nicotine product in the crosshairs of the Food and Drug Administration, which is continuing its years-long crackdown on nicotine use by teens and young adults.

The agency announced today that it issued a warning letter to Krave Nic, which sells gummies containing 1 milligram of nicotine each in three flavors — Blueraz, Cherry Bomb, and Pineapple. The company needs FDA authorization to manufacture or sell this type of product, the agency said in its statement.

“Nicotine gummies are a public health crisis just waiting to happen among our nation’s youth, particularly as we head into a new school year,” said FDA Commissioner Robert Califf in a statement.

This type of nicotine product is a relatively new entry into the market. Nicotine gums designed to help people quit smoking have been around for decades, but gummies, flavored pouches, and other recreational products that aren’t designed to help people quit are a more recent addition. They’re already the second most popular type of nicotine product used by high schoolers, according to a study of kids in southern California published this month that the FDA cited in its statement.

It’s a similar profile to early vapes made by companies like Juul — they taste good, and they’re easy to hide from parents or teachers. “And then the brands are using really modern packaging designs, and they are engaging in digital and social media marketing campaigns,” Alyssa Harlow, a postdoctoral scholar at the University of Southern California Keck School of Medicine who did the research study, told NBC News.

Teen vaping has declined over the past few years. Juul, which stopped selling flavored products after backlash from the federal government, dropped off in popularity among kids — and the FDA is trying to pull it from the market. In the past year, the agency has rejected applications to sell thousands of vaping products and has only allowed tobacco flavors.

But teens and adolescents are still using disposable flavored vapes. And the arrival of gummies offers another avenue for flavored nicotine products. The warning letter and announcement from the FDA show that the agency plans to jump on other nicotine delivery systems that might have a similar appeal to kids and teens.