Massachusetts Attorney General Maura Healey filed suit against Juul Labs Inc. on Wednesday, accusing the popular e-cigarette maker of creating an epidemic through an extensive marketing campaign aimed at hooking minors on its products.

Juul has long denied marketing vaping products to youths, saying it was instead focused on providing adults with an alternative to cigarettes. But the state’s suit said the company bought ad space on children’s websites including Nickelodeon, Nick Jr., and Cartoon Network. Internal documents also showed the company rejected an advertising proposal targeting adults and instead decided to plaster billboards, print, and online ads with images of young fashionable models who the company described as “New York trendsetters who embody the Juul brand and speak to millennial consumers.’’

“This is the first real window into Juul’s marketing plan and what it intended to do to target our kids,’’ Healey said at a news conference, pointing behind to images of young people holding the company’s devices. “This isn’t about getting adults to stop smoking cigarettes — it’s about getting young people to start vaping.’’

The lawsuit seeks damages but doesn’t specify how much. Healey said she is seeking money for treatment and other necessary remedies, but she also wants to end exploitative practices by the company and others like it.

Juul said it had not yet seen the lawsuit but was working to reduce youth e-cigarette use and become approved by the US Food and Drug Administration. The company said it had halted its television, print, and digital advertising, implemented a $1 billion plan to restructure, and decided not to lobby the federal government on flavored vaping policies.

“Our customer base is the world’s 1 billion adult smokers and we do not intend to attract underage users,’’ a Juul spokesman said.

The lawsuit is the latest effort by Healey to target the multibillion-dollar industry over concerns about marketing to young people. One in three Massachusetts high school students reported using e-cigarettes in the past month, she said.

Arizona, California, Illinois, Minnesota, Mississippi, New York, and North Carolina are among the other states that have sued Juul, as well as the District of Columbia.

Northeastern University student Emma Tigerman, 19, told reporters Wednesday that she joined crowds of students vaping nicotine between classes at her high school.

“I found myself beginning to crave the relief of a hit and if I waited too long in between I would grow shaky and irritable,’’ Tigerman said. “I began using it religiously and carrying it around with me always — including during physical education.’’

Healey said many teens are so addicted to Juuls that they sleep with their vaping device under their pillows. She said the company for years targeted young people with its flavors — cool cucumber, mango, crème brûlée — and allowed to persist lax age verification processes that kids could easily circumvent online and at retail stores.

Juul or firms it hired worked to recruit young social media influencers and celebrities with large online followings, the lawsuit said, including the singer Miley Cyrus and actors Kristen Stewart, Robert Pattinson, and Jennifer Lawrence.

“We have a generation of young people who never would’ve smoked who saw these cool high-tech devices … and thought this was the cool, new, safe product,’’ said Matthew Myers, president of the national Campaign for Tobacco-Free Kids. “Your blood will boil when you realize the conscious decisions these companies made that can’t be justified by anybody with any ethical standard.’’

According to Healey’s 66-page complaint filed in Superior Court, Juul purchased advertisements on educational websites geared toward middle school and high school students, such as coolmath.com and socialstudiesforkids.com. Juul also advertised on sites for high school students looking at universities, including collegeconfidential.com.

The company tried to recruit more than 500 social media influencers to promote its products, many who largely had young audiences. They would offer to pay the influencers for resulting sales, the suit says.

The company would recirculate this content on its own accounts. About half of its Twitter account followers were estimated to be between ages 13 and 17 and most were estimated to be under 21, the lawsuit said, citing an article in the Journal of the American Medical Association. Juul contends it complies with state and local laws, but the lawsuit says that it sold e-cigarettes to children and teenagers across the state.

Juul employed a lax online age-verification process, which allowed online users to make multiple attempts to enter “alternate’’ addresses and Juul would allow people to “pass’’ even if the address didn’t match government database records exactly, the lawsuit said. That allowed young people to put in their parents’ names, approximate year of birth, and address, and then have the products mailed to another address.

Juul sold more than 10,000 shipments of e-cigarettes to Massachusetts consumers without verifying the recipients’ ages, the lawsuit says.

The company’s customer service staffers even allegedly advised customers how to evade the age requirements. In a 2018 e-mail, “Don’’ from the “Juul Care Team’’ suggested a consumer whose order was canceled due to failing the age verification could use a friend or relative’s address in Quincy instead of Milton, where the legal age to buy tobacco was 21 at the time. (The legal age is now 21 statewide.)

As part of efforts to curb the recent surge in youth nicotine vaping, Massachusetts enacted the nation’s first law last year banning the retail and online sale of all flavored tobacco and nicotine vaping products, including menthol cigarettes.

Healey said her predecessor, Martha Coakley, who now works for Juul in government relations, was not part of the investigation and she hadn’t spoken to her. “It’s disappointing,’’ Healey said Wednesday, when asked to comment on Coakley’s new job. “This is a company that is just not up to good.’’

Coakley did not return a call seeking comment.

Dr. Jonathan Winickoff, a pediatrician at Massachusetts General Hospital, said at the news conference that he has seen patients suffering from anxiety, depression, mood disorders, asthma, and restrictive lung disease due to nicotine vaping. Studies show the products can also impact brain development, contain cancer-causing chemicals, and be highly addictive, he added.

“These are serious and potentially irreversible conditions,’’ Winickoff said.

For her part, Healey said the lawsuit is "more than just about money, though we do need money for treatment. It’s also about ending practices.’’

Naomi Martin can be reached at naomi.martin@globe.com.