Editor's note: Pseudonyms are used for the names of the young people in this story.
(CNN) -- "Have you heard of molly?" the girl next to me asked. She was swaying from side to side, bobbing her head to the bass vibrating throughout the sold-out venue.
The room around us was buzzing with anticipation. Music was blasting. People were dancing and laughing and taking pictures. There was less than an hour until showtime, and I was about to see one of my favorite artists, so I was feeling pretty good. The girl next to me, Jessica, was obviously feeling better.
I turned to my fellow concertgoers, watching as they met Jessica's eyes, nodding their heads knowingly. Of course they had heard of molly.
Turns out, molly is a pretty popular lady these days.
According to the Drug Enforcement Administration, molly is the powder or crystal form of MDMA -- or 3, 4-Methylenedioxymethamphetamine, a chemical drug most commonly known for its use in the pressed pill Ecstasy.
Unlike Ecstasy, which has a reputation for being laced with everything from caffeine to methamphetamine, molly -- a name shortened from "molecule" -- is thought of as "pure" MDMA.
The DEA labels it an illegal Schedule 1 controlled substance, considered to have a high potential for abuse and no accepted use in medical treatment.
Molly is abundant at music festivals -- if you know where to look. The third and final day of New York's Electric Zoo music festival was canceled Sunday after two concert-goers died and at least four others were hospitalized due to what is believed to be MDMA-related causes, police said; it is unclear whether the drug was used in Ecstasy pills or in its "pure" form of molly.
Last year, at Miami's Ultra Music Festival, fliers littered the landscape mentioning her name like missing child posters: "Have you seen molly?" And when Madonna took to the stage to introduce an artist, the pop star asked the audience: "How many people in this crowd have seen molly?" A slew of cheers answered, though Madonna later said she'd been referring to a song, not to an illegal drug.
Hip-hop artists claim they know her -- she's casually mentioned by 2 Chainz in the Nicki Minaj track "Beez In the Trap," by Childish Gambino in his song "Unnecessary," by Kanye West in "Mercy," by Danny Brown in "Die Like a Rockstar." Even Miley Cyrus is familiar, although the line "We like to party, dancing with molly" was bleeped out in her most recent performance of "We Can't Stop" on the MTV Video Music Awards.
It seems the drug is on the minds of many. But questions about who -- or what -- molly really is remain.
Contradictions about makeup
An experience with molly starts with a bitter taste, users say, which is soon forgotten as the high kicks in.
"It felt like everything was amplified. It felt euphoric -- almost like a crazy adrenaline rush for a long time," said Evan, a young professional working in Michigan.
"You feel a lot more loose and comfortable in your environment," said recent Georgia high school graduate Jessica, who'd never used molly until the concert last summer -- a friend's recommendation convinced her to give molly a try.
And then, usually after a few hours -- depending on the dose that is taken -- of dancing and moving and talking, the trip comes to an end.
"(After it was over), it wasn't like a depression, but it was like, 'Aw man, I wish I felt that way again,' " Jessica said.
MDMA acts as a stimulant and a psychedelic, according to the DEA. After being inhaled, eaten or parachuted -- folded into a tissue and swallowed -- molly ushers in euphoria. It floods users' brains with neurotransmitters serotonin, norepinephrine and dopamine, making them feel elated, empathic and full of energy.
MDMA first found popularity in the form of Ecstasy as the drug of choice among ravers at underground nightclubs in the early 1990s. But when questions arose over the purity of Ecstasy --- the drug was often mixed with other ingredients ---- people turned their attention to a purer form, Nathan Messer, chairman of the board for the nonprofit organization DanceSafe, which promotes health and safety within the nightclub community, told CNN in 2012.
"You knew you were getting the real thing and nothing but the real thing," he said. "Because people knew that (molly) was trustworthy, it became the go-to thing."
Molly is a street name that has been in use for about a decade, Messer said. Although it originally referred simply to MDMA, the title "molly" is now given to a variety of legal substances with similar chemical structures.
Messer said MDPV, methylone, mephedrone and butylone -- different substances or drugs -- are often sold as molly, while users such as Evan have heard countless rumors of molly's makeup, including that it's created from fertilizer.
Number of users unclear
Molly users tend be between the ages of 16 and 24, Pax Prentiss, co-founder and CEO of Southern California's Passages rehabilitation centers, told CNN last year.
Exact numbers detailing molly's use are unclear -- studies conducted by U.S. health organizations such as the Substance Abuse and Mental Health Services Administration usually only quantify use of MDMA or Ecstasy, not molly specifically. But molly appears to be gaining popularity.
As the owner of a film company that shoots music videos and festivals, Evan often sees molly in use at shows.
And even for someone who doesn't consider himself to be an avid drug user, he said he found it easy to get his hands on some molly.
"All I had to do was text a friend," Evan said.
Because MDMA has long been associated with raves, the mainstream popularity of electronic dance music also contributed to molly's rising reputation, DanceSafe's Messer said.
In 2011, about 25 kilograms of molly worth at least $525,000 were recovered after a DEA investigation of a large-scale drug trafficking operation based in Syracuse, New York, a college town. The bust led to charges against 20 people.
Penn State University Police Chief Tyrone Parham told CNN he and his officers first heard anecdotes about molly in 2011.
Parham said it's hard to get a real idea of how many students have used molly. Officers can catch users of marijuana -- the most common drug on Penn State's campus, according to Parham -- in the act because of the drug's conspicuous odor. But it's difficult to know if a student has misused molly because officers are often called after the drug has already been ingested -- if they are even called at all.
"I think it's one of those things, not just here but across the country, (that's hard) to get an understanding of how prevalent it is," he said.
A name with innocent appeal
Some consider the name picked for this white powder a clever marketing strategy: "Molly" carries both the innocent appeal of the girl next door and the implication that the drug is always pure MDMA. But because the chemical makeup of molly is often altered, taking the drug is dangerous, DEA spokesman Rusty Payne told CNN in 2012.
"(Suppliers) are making it look like something that is safe and easy to take, but in many cases, you're playing Russian roulette," Payne said.
And although MDMA tastes, smells and affects you differently than other drugs would, without having experience with each molly variation, there's no easy way to tell if the substance you take is pure, Messer said. But even as its pure form molly, MDMA can be dangerous.
The DEA sees MDMA supplied from Asia, Canada, even the Netherlands.
"You have no idea the lab environment these chemicals or substances were produced in," Payne said. "If they knew where things were produced, they might think twice."
Some drug users have said they prefer molly over other illicit drugs because of the limited negative side effects they've experienced.
"Honestly, if I were to pick a drug out of anything else to do, I would pick molly," Evan said. "Molly has a lot to do with loud music and seeing lights -- getting excited about seeing something that's already cool and making it cooler."
Because prolonged use eventually begins to diminish users' highs, the risk of physical addiction is low, said Prentiss, the Passages rehab CEO. MDMA addictions make up less than 5% of the company's clientele, he said.
And hospital visits spurred by MDMA use appear to be few and far between. Less than 4% of emergency room visits in 2009 were because of MDMA, according to the Drug Abuse Warning Network, which is part of the Substance Abuse and Mental Health Services Administration.
In fact, with its mood-enhancing properties, MDMA is even being studied as a possible treatment for post-traumatic stress disorder.
But the Drug Abuse Warning Network's study also found that from 2004 to 2009, there was a 123% increase in the number of emergency room visits involving MDMA taken alone or in combination with pharmaceuticals, alcohol or both.
Theodore Bania, a medical toxicologist and emergency medicine physician at St. Luke's-Roosevelt Hospital in New York, said although many of the people who take molly don't end up in the emergency room, some users experience side effects that land them in the hospital.
MDMA, even in its pure form, can produce elevated heart rates and distortion of thought processes, causing users not to realize their rising body temperature or fading stamina as they continue to party. Combining MDMA with alcohol or other drugs can also be the cause of its more serious side effects.
Bania frequently sees patients who have complications from MDMA, ranging from dehydration and exhaustion to more severe side effects such as hyperthermia, seizures, electrolyte abnormalities, cardiac episodes and comas.
MDMA also depletes the body of some of its neurotransmitters, which can lead to a decreased mood about a day or two after using the drug. Prentiss said he has even seen the drug lead to long-term depression.
Users who haven't had exposure to molly's serious negative side effects sometimes think of it as a "safer" drug. But Hart, the Columbia associate professor, said claims that any drug is safe are ridiculous.
"A lot has to do with the doses people take," Hart said. "As you increase the dose over an extended period of time, you can expect to see some negative effects. That's a general rule the public really needs to understand."
Hart said he believes accurate education, not law enforcement, is key to minimizing the risks of illicit drugs such as molly. Because so many young people have already tried molly, he said experts need to make sure they are being realistic about the dangers of its use.
"What we've done and what we consistently do is we include people that exaggerate the harms," Hart said. "Kids are not listening because they've already had the experience. ... They (think they) should reject everything we're saying because we're not being accurate, and they know it."
'A softening against drugs'
Molly's rise in popularity can, in part, be attributed to the current culture, Tammy Anderson, a professor of sociology and criminal justice at the University of Delaware, told CNN in 2012. Anderson has studied the use of drugs, including MDMA, in nightclubs. "We're at a place here historically that people don't think marijuana is a drug anymore."
Although marijuana, like molly, remains on the DEA's list of Schedule 1 controlled substances, it's a drug that many citizens think of not only as minor but as one that should be legal. And 17 states have legalized it for medical use.
There is now greater permissiveness and lax attitudes toward drugs such as marijuana, so people move on to other substances, such as molly, and give themselves permission to use them, Anderson said.
"We are moving into a post-war on drugs era. We're seeing a softening of drug laws and a softening against drugs, especially among young people."
For now, the DEA is more focused on fighting the abuse of prescription medications such as Oxycontin and Valium. But as admirers plaster posters at concerts asking, "Have you seen molly?" officials can only hope she stays missing.