The US surgeon general has urged an aggressive clamp down on e-cigarettes, recommending punitive taxes and bans on them being used at indoor public venues.
It followed an explosion in "vaping" – inhaling e-cigarettes – among teenagers, with figures showing one in five high school pupils were using them.
Jerome Adams, America’s top doctor, said action was needed to prevent millions of teenagers becoming hooked on the high-nicotine devices.
In a rare public advisory he said parents, teachers and doctors must work together to address an epidemic of underage vaping, which was putting the health and brain development of young people at risk.
E-cigarettes and other vaping devices have been sold in the US since 2007 and are now a $6.6 billion business.
Most devices heat a flavored nicotine solution into an inhalable vapour, and have been marketed to adult smokers as a less-harmful alternative to cigarettes.
However, some research suggests that teenagers who vape are more likely to then try regular cigarettes.
US law bans the sale of e-cigarettes to people under 18.
But a government survey found an estimated 3.6 million US teenagers currently use e-cigarettes.
In the past year use increased by 78 per cent among high school pupils, with one fifth of them now using the devices. For 17 and 18-year-olds the figure rose to 37 per cent.
Mr Adams singled out Juul, a Silicon Valley company, which has come to dominate the e-cigarette market with devices featuring flavours like mango and cucumber.
The surgeon general said each Juul cartridge contains as much nicotine as a pack of cigarettes.
He said: "We do know that these newer products, such as Juul, can promote dependence in just a few uses.
"We must take aggressive steps to protect our children from these highly potent products that risk exposing a new generation of young people to nicotine."
He added: "E-cigarette aerosol is not harmless. Nicotine exposure during adolescence can harm the developing brain which continues to develop until about age 25."
Mr Adams said e-cigarettes could also potentially expose bystanders to other harmful substances, including heavy metals,
Last month Juul shut down its social media accounts and halted in-store sales of its flavoured cartridges to deter use by under-18s.
In a statement the company said: "We are committed to preventing youth access to Juul products."
The surgeon general’s warning came as Andrew Cuomo, the governor of New York, said he would aim to legalise cannabis for recreational use there next year.
It would mean America’s most populous city being added to the list of places that allow use of the drug. So far, 10 US states and the District of Columbia have legalised cannabis for recreational use.