(CNN) Beginning September 30, kratom will be considered a Schedule I drug , a substance that has "no currently accepted medical use and a high potential for abuse," the Drug Enforcement Administration announced today.

Other Schedule I drugs include heroin, LSD, marijuana and ecstasy.

In this week's Federal Register , the DEA proposes designating the drug as Schedule I for up to three years. After that time, the status could be extended permanently. Up until this point, it has been considered a supplement, loosely regulated by the Food and Drug Administration.

What is kratom?

Native to Southeast Asia, the kratom tree's leaves have been used for centuries as an herbal drug by laborers and farmers. Today, kratom leaves are ground into pills and powders, and sold as a dietary supplement. It can be found in head shops and online. It's even made into drinks in some bars

When taken at low dosages, kratom can act like a stimulant, heightening alertness. At higher doses, kratom is a sedative, producing opioid-like effects that dull pain.

It has this effect because mitragynine and 7-hydroxymitragynine -- the active ingredients in kratom -- bind to the opioid receptors in our body, said Dr. Ed Boyer , a professor of emergency medicine at the University of Massachusetts Medical School, who has done a handful of studies on the substance. It's several times more potent than morphine, Boyer said, and "dulls pain very well. ... You can have very, very good analgesia."

But unlike opioid drugs such as hydrocodone or heroin, kratom doesn't appear to slow breathing, Boyer said.

Federal agencies act on kratom

In 2014, the FDA issued an import alert that allowed US Customs agents to detain kratom without a physical examination. "We have identified kratom as a botanical substance that could pose a risk to public health and have the potential for abuse," said Melinda Plaisier, the FDA's associate commissioner for regulatory affairs.

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According to the DEA, between February 2014 and July 2016, nearly 247,000 pounds of kratom were seized.