WASHINGTON — The Drug Enforcement Administration has received a torrent of backlash from patients with chronic pain and former opiate users after announcing plans to ban kratom, a plant gaining popularity across the United States for its opiate-like effects.

Kratom, which originates in Southeast Asia, has become more widespread in the United States in the past decade, fueled by online testimonials from users and a lack of federal regulation. Advocates say the plant – typically crushed and mixed or brewed with water – poses few health risks while helping users relieve severe pain and overcome addictions to powerful prescription painkillers.

A DEA spokesman told The Washington Post that the agency has received a surprising number of comments about the ban and could ease the restrictions after further research.

The Food and Drug Administration began seizing some kratom shipments from overseas in 2014. This summer, the Centers for Disease Control and Prevention reported that annual calls to poison-control centers related to kratom use jumped from 26 in 2010 to 263 in 2015.

Alabama and Arkansas outlawed the substance earlier this year, joining four others – Indiana, Wisconsin, Vermont and Tennessee – according to the American Kratom Association.

The DEA recently announced a temporary federal ban on kratom beginning Sept. 30. The active chemicals in the plant will be placed on Schedule 1 of the Controlled Substances Act, the most restrictive regulatory category, designated for substances with no medical use and a high potential for abuse.

“The placement of these opioids into schedule 1 of the Controlled Substances Act is necessary to avoid an imminent hazard to the public safety,” the DEA wrote in the Federal Register. The agency’s notice cited reports of 15 deaths linked to, though not necessarily attributable to, kratom use between 2014 and 2016.

The ban would automatically end after two years unless the DEA acts, and spokesman Melvin Patterson said he could see the agency moving kratom from the highly restrictive Schedule 1 to the less-restrictive Schedules 3 to 5, reserved for minimally addictive drugs with accepted medicinal use.

“I don’t see it being Schedule 2 (or higher) because that would be a drug that’s highly addictive,” he said. “Kratom’s at a point where it needs to be recognized as medicine.”

Patterson cautioned that research would be necessary to know for sure how to best regulate the drug, and it’s safest to put kratom on Schedule 1 in the meantime. Still, he noted that public response to the ban has been overwhelming.

“That was eye-opening for me personally,” he said. “I want the kratom community to know that the DEA does hear them. Our goal is to make sure this is available to all of them.” he said.

John Hudak, a drug policy expert at the Brookings Institution, said it’s fairly common for the DEA to temporarily ban a drug and later ease the restrictions, often as a result of lobbying and research from pharmaceutical companies hoping to sell them. It’s less common for a scheduled drug to be removed from the list of controlled substances altogether, but it does happen.

Still, Hudak said, the strict scheduling of kratom would make it harder for researchers to access the drug, which could limit the research that the DEA says is necessary to determine whether it has medical benefits.

Kratom has been used in the Southeast Asia for recreational and medical purposes for centuries, according to a 2011 report from the Transnational Institute, a research and advocacy organization.

Traditionally, people in the region chewed it to produce a mild stimulant effect, similar to coffee.