While the new Russian drug makes for good headlines, it’s far from the greatest drug threat facing the U.S.

Two Illinois women were among the first documented U.S. users of krokodil, a Russian “flesh-eating” drug that’s a cheaper, synthetic form of codeine.

The two women say that they believed they were injecting heroin, but had unknowingly received krokodil, which is reportedly 10 times stronger. The drug gets its name from its ability to turn users’ skin scaly, like a crocodile’s.

Yet while krokodil sounds terrifying, it is far from the worst drug offender in America.

Christopher Crosby, CEO of The Watershed Addiction Treatment Programs, says that of the 12,000 monthly calls the treatment provider receives on its hotline, only about a dozen have been about krokodil. In the last month, none of their 350 new admissions have been for krokodil.

“It is very minuscule right now, but who knows, it could sweep the nation,” he told Healthline. “We’re seeing the tried and true real drugs.”

According to data from the U.S. Department of Justice, the Substance Abuse and Mental Health Services Administration (SAMHSA), the National Institute on Drug Abuse (NIDA), the U.S. Food and Drug Administration (FDA), and the U.S. Centers for Disease Control and Prevention (CDC), the following are the biggest drug threats in the U.S.

MDMA, or ecstasy, is a popular club drug. Its purer, crystallized form, “molly,” has been mentioned by pop stars like Miley Cyrus and hip hop artists like Trinidad James, who coined the refrain, “Popped a Molly, I’m sweatin’.”

“Sweating” refers to the body temperature increase—which has been fatal in some cases—and other symptoms that go along with the drug’s euphoric high.

It’s increasingly available in the U.S. due to smuggling from Canada. The drug is most popular in New York and New Jersey, along with the Great Lakes, Southwest, and Pacific regions.

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About seven million Americans abuse prescription drugs. According to NIDA, the majority of these drugs are either painkillers, tranquilizers, or stimulants. After marijuana and synthetic marijuana, prescription drugs are the most common substances used by high school seniors, with one in 20 reporting using Vicodin or Oxycontin.

The death rate from prescription painkiller overdose—specifically opioid painkillers, such as hydrocodone and oxycodone—rose 415 percent among women and 265 percent among men from 1999 to 2010, according to a CDC study released earlier this year.

Opioid painkillers accounted for more than 15,500 fatal overdoses in 2009; the FDA refers to them as the heroin of the 21st century.

Unlike with heroin, however, painkiller overdose deaths occur most often in higher-income neighborhoods, according to a new study in the American Journal of Public Health. The study conducted by researchers at Columbia University’s Mailman School of Public Health found that analgesic painkiller deaths, including from oxycodone and codeine, occur more often in economically disadvantaged neighborhoods, with a high rate of divorce and single-parent homes.

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As ongoing crackdowns on “pill mills” make opioid prescription drugs harder to obtain, heroin use is exploding.

“Without access to these strong painkillers, they’re going to look for something else,” Crosby said.

From 2007 to 2012, the number of U.S. heroin users increased from 373,000 to 669,000. Many say this is a low estimate because many heroin users are homeless, incarcerated, or otherwise outside the reach of pollsters.

While cocaine availability is down in the U.S. due to drug enforcement and cartel infighting, the shortage, coupled with an increase in poppy farming in Afghanistan, has lead to a surge in heroin trafficking, the U.S. Department of Justice reports.

Synthetic drugs enter the U.S. legally from foreign manufacturers who sell them primarily over the internet, or at smoke shops and gas stations.

The “bath salts” drug that received widespread media attention earlier this year was MDPV, a psychoactive drug with stimulant qualities. Users are prone to hallucinations, stripping off their clothes because of overheating, and “zombie”-like behavior.

Synthetic marijuana is often sold as incense, called Spice and K2. Unlike actual marijuana, the synthetic version can cause vomiting and increased agitation.

If you still think it might be a good idea to try synthetic marijuana, take advice from Dr. John W. Huffman, a Clemson University organic chemistry professor whose 1995 research paper on synthetic cannabinoids led to the recipe for synthetic marijuana like K2: “People who use it are idiots.”

Marijuana has been and remains the most popular illegal substance in the U.S. While many states are legalizing marijuana for personal or medical use, it is not legal anywhere for minors, mainly due to its purported effects on the developing brain.

SAMHSA administrator Pamela Hyde said marijuana use in 12- to 17-year-olds can cause “significant I.Q. declines.”

“There’s no question that marijuana is harmful to the developing brains of adolescents,” she said during a press conference last month.

However, marijuana is still the only controlled substance in the U.S. that has yet to kill anyone from overdose.

No addictive drugs are more common in the U.S. than nicotine, caffeine, and alcohol, and they create more health problems due to their widespread use.

Available in many forms and flavors, these drugs are some of the most easily avoidable risk factors for major diseases and premature death, including accidental deaths.

Eighty-three percent of adult Americans drink coffee, at an average of three cups a day. In 2012, 60 million Americans binge drank, meaning they had more than five drinks in one sitting, and 70 million Americans were smokers.

“Alcohol is still the largest drug of addiction,” Crosby said. “You don’t have pure alcoholics anymore. It’s rare that you have an addict that uses only alcohol. Thirty years ago you did, but not anymore.”