A group of scientists who have studied kratom are warning the Trump administration that banning the drug would worsen the opioid epidemic, following a declaration from the Food and Drug Administration that kratom has “opioid properties” and is associated with 44 deaths.The drug, a Southeast Asian tree leaf, is legal under federal law, but FDA officials have recommended it be categorized as a Schedule 1 drug, which would effectively mean that scientists would be unable to study its effects. People who take the drug, which can be sipped in a tea or taken as a pill, say that is has helped them beat off cravings for opioids and has alleviated chronic pain and depression.The scientists pleaded against a kratom ban in a letter sent to Robert Patterson, acting administrator of the Drug Enforcement Administration, and Kellyanne Conway, counselor to the president who is overseeing the administration’s efforts on the opioid crisis.

They raised doubts about the deaths determined to be associated with kratom and drew attention to surveys that have indicated that kratom was being used as “a lifeline away from strong, often dangerous opioids for many of the several million Americans who use kratom.” For these users, they wrote, a ban would result in “relapse to opioid use with the potential consequence of overdose death.” Instead, they wrote, the government should be encouraging research on the product to assess its safety and effectiveness.

“Placing kratom into Schedule I of the [Controlled Substances Act] will … have a profound and pervasive chilling effect on this needed additional research,” they wrote.

The latest available federal data show that 42,249 people died from an opioid overdose in 2016, whether from heroin, fentanyl, or prescription painkillers. Of the deaths, 3,373 were caused by methadone, a medication often prescribed to treat people with addictions to opioids.

FDA Commissioner Scott Gottlieb has said that his agency was concerned about reports that people had been using kratom to wean themselves off opioids, saying “there is no reliable evidence to support the use of kratom as a treatment for opioid use disorder and significant safety issues exist.” He has warned in the past that kratom can cause seizures and liver damage.

The DEA has not said whether it intends to take action given the latest analyses and recommendations by the FDA and does not have a specific deadline. The agency said in October 2016, during the Obama administration, that it would hold off on banning kratom as a Schedule I substance such as heroin, marijuana or LSD, as it waited for additional public comment as well as FDA recommendations.