The Food and Drug Administration issued a strong warning on Tuesday against the use of an herbal opioid treatment called kratom, saying regulators have linked it to the deaths of 36 people who were exposed to the substance.

Kratom is an herbal supplement made from a plant native to Southeast Asia. It is primarily used to treat chronic pain, anxiety, and depression, as well as to relieve opioid addiction, the Washington Post reported.

In the U.S. it is sold in different forms, ranging from bags of raw kratom powder to energy drinks and tablets. It is available in different stores, including groceries and gas stations.

Opioids, which include prescription painkillers, contributed to the deaths of 33,000 users in the U.S. in 2015, according to data from the Centers for Disease Control and Prevention. President Donald Trump declared the opioid crisis a public health emergency in October in response to the epidemic. To provide a solution to the crisis, Indianapolis and 75 other cities and states have pursued a joint federal lawsuit against opioid manufacturers and distributors.

Due to the public opposition against opioid, people dependent on it for relief turn to kratom, a treatment that is heavily touted by its proponents as a safe and effective substitute for opioids.

However, as consumers’ dependence on the supplement increases and its availability becomes more widespread, FDA Commissioner Scott Gottlieb warned that kratom actually “has addictive qualities” and is believed to be “fueling new addictions.”

Kratom is being sold in different forms, including powder and tablets. [Image by Joe Raedle/Getty Images]

The FDA said in a statement that it is aware of 36 kratom-related deaths and is already taking measures to control the distribution and use of the substance. Although it is not classified as an opioid, its active ingredients produce opioid-like effects, such as euphoria. Since it is widely used as an opioid substitute, authorities are concerned that it might actually worsen the opioid crisis instead of curbing it.

Overseas, kratom is banned in 16 countries, including Thailand and Malaysia, where it originates, as well as Germany, Australia, and Sweden. In the United States, it is banned in Alabama, Wisconsin, Arkansas, Indiana, and Tennessee.

Supporters of kratom, however, claim that it is a safe alternative for opioids in treating certain conditions, such as chronic pain and anxiety, because it is a plant-based product. However, Gottlieb said there is no “reliable evidence” to support the effectiveness of kratom as a treatment for opioid dependency and that there are no other FDA-approved uses for the substance.

Kratom is touted by supporters as a safe treatment for chronic pain. [Image by meen_na/Thinkstock]

Interestingly, a study conducted by researchers at Columbia University found that kratom contains an alkaloid named mitragynine. This alkaloid activates opioid receptors without triggering respiratory depression, HuffPost reports. This respiratory depression is an effect common to narcotic painkillers, which typically leads to a fatal overdose. Thus, the researchers concluded that it is still possible for drugmakers to develop safe kratom-based pain medications.

Because of the multiple claims about the positive effects of kratom, authorities are also not closing their doors on the probability of using kratom as a means to reduce opioid use.

“We also believe that if it does have therapeutic benefits, and it can be helping people, we want to see the science that can help prove that,” Gottlieb told CNBC’s Squawk Box.

For now, the FDA is conducting a formal scientific and medical evaluation of kratom in order to assess how the substance should be classified.

[Featured Image by Joe Raedle/Getty Images]