(Reuters) - U.S. Surgeon General Jerome Adams on Tuesday issued a rare advisory here, calling for aggressive steps against e-cigarette use among teens, which he said has become an "epidemic".

FILE PHOTO: A woman holds a Juul e-cigarette as she uses her phone in New York City, U.S., September 13, 2018. REUTERS/Brendan McDermid/File Photo

The detailed advisory listed various strategies that states, communities, health professionals and parents can apply to restrict the use of e-cigarettes.

E-cigarettes are handheld devices that induce the feeling of smoking by delivering nicotine, flavorings and other additives to the user through an inhaled aerosol.

The devices, which are often thought of as safer alternative to cigarettes, are not harmless, the advisory noted.

E-cigarettes have become increasingly popular among teens because they come in “easy to conceal” shapes such as USB-flash drives, the advisory noted.

“One of the most commonly sold USB flash drive shaped e-cigarettes is JUUL, which experienced a 600 percent surge in sales during 2016-2017, giving it the greatest market share of any e-cigarette in the U.S. by the end of 2017,” the advisory said.

E-cigarette maker JUUL Labs has been under intense scrutiny and was cited as one of the main culprits for the increased usage.

In September, the U.S. Food and Drug Administration said it was mulling a ban on flavored e-cigarettes from makers including JUUL, Vuse and MarkTen XL, citing the threat of creating a new generation of nicotine addicts.

More than 3.6 million U.S. youth, including one in five high school students and one in 20 middle school students, use e-cigarettes in 2018, the advisory said.

Alex Azar, secretary of the U.S. Department of Health and Human Services, pointed to recent data from the National Institute on Drug Abuse that showed the percentage of high school seniors who used e-cigarettes in the last 30 days nearly doubled to 20.9 percent from last year.

The public health community is often “late to the game” on critical issues involving young people, Adams told Reuters on Tuesday.