The brightly colored packaging is a slick mix of ombré pink and lime green. The nicotine inside comes wreathed in a “strawberry kiwi” flavor.

Increasingly, plastic disposable vapes like this one are making their way into the hands of children, with one in five young people in Britain between the ages of 11 and 17 trying vaping last year, according to Action on Smoking and Health, an independent public health charity.

Soon, they will be banned in Britain, Prime Minister Rishi Sunak announced on Monday, as he unveiled a package of measures to ban single-use vapes, restrict flavors, and regulate packaging and displays.

Britain is following several other nations, and a number of American states, that have already taken steps to curb underage vaping, as the colorful and trendy packaging and fruit or candy flavoring has proved appealing to teenagers and children.

Mr. Sunak said that the ban, which is part of legislation that still has to be approved by Parliament, was intended to halt “one of the most worrying trends at the moment,” before it becomes “endemic.”

“The long-term impacts of vaping are unknown and the nicotine within them can be highly addictive, so while vaping can be a useful tool to help smokers quit, marketing vapes to children is not acceptable,” he said in a statement.

Andrea Leadsom, Britain’s health minister, said the measures were intended to make sure that vapes were aimed at adults who were quitting smoking, rather than children.

“Nicotine is highly addictive — and so it is completely unacceptable that children are getting their hands on these products, many of which are undeniably designed to appeal to young people,” she said in a statement.

Recent surveys suggest a sharp uptick in the number of young people vaping in Britain. In 2023, 20.5 percent of children 11 to 17 had tried it, up from 15.8 percent in 2022 and 13.9 percent in 2020, according to data from Action on Smoking and Health, an independent public health charity.

The charity said that the vast majority were using a disposable, single-use vapes, and the most popular brand was Elf Bar, with fruit or soda flavors most used by that age group.

Disposable vapes, which contain lithium batteries, also damage the environment, with an estimated five million thrown away each week in Britain in 2023, up from 1.3 million a year earlier, according to government statistics.

Last week, Dr. Tedros Adhanom Ghebreyesus, the director general of the World Health Organization, said he was concerned about growing vape use by young people, and he urged member states “to take swift action to counter this emerging threat.”

Speaking at a meeting of public health officials in Geneva on Wednesday, Dr. Tedros said that while the tobacco industry presented vaping as harmless, “it is full of harm and it’s actually hurting children.”

“You hook them with this, they think it’s smart, fashionable, cool,” he said of efforts by vape producers to market to young people, “And then they will be customers of the tobacco industry for life, that’s what’s happening.”

He likened it to “history repeating itself but with a different form, the same nicotine with a different package,” drawing parallels between the early days of marketing cigarettes to young people.

While it is not illegal for people under 18 to smoke or vape in Britain, it is illegal for those products to be sold to them. By banning disposable vapes, and restricting the flavors and packaging of refillable vapes, the government hopes to make it far less likely that young people will experiment with e-cigarettes.

The measures announced on Monday are part of a broader government strategy to curb overall tobacco use. Last year Mr. Sunak announced plans to make it illegal to sell cigarettes to anyone born on or after Jan. 1, 2009, so that those turning 15 this year or younger will never be able to buy them legally.

Other countries are seeking to curb the appeal of vaping to young people. Australia introduced sweeping legislation late last year that bans all vaping without a prescription. French lawmakers have backed a proposal to ban single-use vapes. And New Zealand has introduced regulations on marketing vapes to children.