Kratom is a drug of paradoxes.

The botanical substance is both a stimulant and a sedative. It is touted as a safer alternative to heroin but it, too, is addictive and potentially life-ruining. It is common and illegal in Thailand, where it grows naturally, but little-known and largely legal in the United States. It has a long and confusing list of possible side effects. And for now, it is relatively easy to obtain—but perhaps not for much longer.

The federal government is cracking down on kratom. Last month, the FDA asked U.S. Marshals to seize nearly 90,000 bottles of dietary supplements containing kratom, which is derived from tropical trees that grow throughout Southeast Asia. In 2014, the Marshals took over 25,000 pounds of raw kratom from a company in Van Nuys, California, at the FDA’s request.

The FDA has also issued an “import alert” for kratom and the Drug Enforcement Administration (DEA) lists it as a “Drug and Chemical of Concern” (PDF).

The increased federal scrutiny comes on the wake of its emergence in the past few years as a hot new “Internet drug.” The kratom faithful say that it is psychoactive but safe, and that it acts like an opioid with a much lower risk of overdose-related death.The widespread use of kratom in Thailand has fed into its image in U.S. drug culture as a Southeast Asian herbal supplement that is being treated with undue suspicion by the federal government. For example, Vice recently argued that “banning it might do more harm than good,” pointing to its long history of use in Thailand and Malaysia. As the DEA notes (PDF), kratom was traditionally used as a stimulant by Thai and Malaysian laborers and farmers.

Kratom has been relatively easy to obtain stateside despite the FDA import alert because it is not regulated under the Federal Controlled Substances Act. It can be bought online and consumed as a tea, taken orally as a pill, or chewed as a leaf, and it has only been formally criminalized in four states. But the recent action from the FDA and the DEA has Kratom users fearing criminalization.

What, exactly, does kratom do? The FDA told The Daily Beast that the drug has been “indicated to have both narcotic and stimulant-like effects.” According to the DEA, low doses of kratom can cause “increased alertness, physical energy, and talkativeness” (PDF) and high doses have a sedative effect. Kratom addicts have reported “psychotic symptoms, including hallucinations, delusion, and confusion.”

Some kratom users take it for its opioid-like effects to manage chronic pain or to replace an opioid addiction. The American Kratom Association promotes it as a “natural analgesic which has been used for hundreds of years to safely alleviate pain.” But, as The New York Times reported, addicts seeking an opiate replacement risk relapse. One heroin addict the Times interviewed, Dariya Pankova, started drinking a kratom beverage to treat her withdrawal symptoms without knowing that it, too, could be addictive. After getting hooked on kratom, she started craving heroin again and went back to abusing the more dangerous drug.

“It’s preying on the weak and the broken,” she said of kratom’s growing popularity.

Meanwhile, the drug has built up a core following of recreational users. The Reddit community r/kratom now boasts over 7,000 members who, as Vocativ reported, can’t quite seem to agree on even its most basic effects: Does it make you feel good or bad? Does it make sex better or worse? Does it give you diarrhea or constipation? Is it a “miracle plant” or an addictive substance that can make you lose your job and feel suicidal?

“My [girlfriend] insists kratom gives her the runs,” said one r/kratom member.

But another said, “I’m not getting a damn thing out of kratom except a backed-up poop chute.”

Because kratom can make some users feel more sociable, some take it to alleviate social anxiety. For instance, one Reddit user wrote that “talking to and meeting new people is a lot easier while high on kratom.” But the first person to respond to him had words of warning: “At first, yes. It was great. Then I started using it daily like everyone said not to and, after about 6 months, it started actually giving me anxiety.”

The FDA and DEA are wary of kratom’s effects, especially in the event of long-term use. The FDA told The Daily Beast that it can come with a variety of side effects including “respiratory depression, vomiting, nervousness, weight loss, and constipation.” Withdrawal symptoms include “hostility, aggression, excessive tearing, aching of muscles and bones, and jerky limb movements.”

The DEA has received reports of several cases of psychosis caused by kratom use (PDF). The law enforcement agency notes that its effects include “nausea, itching, sweating, dry mouth, constipation, increased urination, and loss of appetite.” Long-term users can experience anorexia and insomnia.

There are rare reports of death, although they typically occur in conjunction with the use of other, more dangerous drugs.

But groups like the Amsterdam-based Transnational Institute (TNI) are opposed to the criminalization of kratom. TNI Program Director Martin Jelsma told The Daily Beast that “it would make sense to allow a regulated market for mild plant-based stimulants, including natural coca products” and kratom.

“Although the plant itself has well-documented analgesic properties—and has been widely used in Thailand for decades, not least as an aid in opiate withdrawal—its characterization as an illicit drug looks set to engender all the unfortunate consequences, in social and medical terms, that it could never have managed to produce on its own,” the TNI wrote in a policy position on kratom. “The record of the official response to kratom consists, sadly, of an exemplary case of harm aggravation.”

But given the recent raids and the heightened DEA scrutiny, kratom’s days may be numbered. And if it does become a controlled substance, the Internet’s neverending search for the mythical “safe” high will surely continue.