FDA warns about herbal drug kratom, used for pain relief: What to know about side effects

Millions of Americans have turned to kratom, an over-the-counter herbal drug extracted from the leaves of a tree native to Southeast Asia, for relief of pain, anxiety and even withdrawal symptoms from opioids.

But the Food and Drug Administration has said kratom may be harmful. The agency has sought to restrict imports of the substance and recently seized a large shipment to an Oklahoma manufacturer.

Still, millions of users regularly buy kratom as pills, capsules or other forms at convenience stores and smoke shops.

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Here's what to know about kratom, its side effects, how it's sold and its legality.

What is kratom?

Kratom is extracted from the leaves of Mitragyna speciosa, a tree native to Thailand, Malaysia, Indonesia and Papua New Guinea. The products are marketed as herbal supplements that users claim relieve pain, boost energy, treat anxiety and ease withdrawal symptoms from opioids.

The FDA said kratom contains psychoactive ingredients and binds to the same opioid brain receptors as morphine. The agency says the unregulated substance appears to put users at risk of addiction and abuse.

A trade group, the American Kratom Association, disputes the claim and says the FDA has "unfairly demonized" kratom for more than a decade.

What are kratom's side effects?

The FDA hasn't approved kratom for therapeutic use and has warned consumers of "concerning reports about the safety of kratom."

Though the Centers for Disease Control and Prevention and the National Institute on Drug Abuse (NIDA) have called for more research on long-term effects of kratom, the federal agencies said the substance is linked to known harms and can create opioid- and stimulant-like effects.

According to NIDA, unregulated products marketed as kratom might be contaminated with heavy metals and harmful bacteria.

People have experienced side effects such as agitation, confusion, sedation, hallucinations, seizures and liver toxicity, according to a 2021 World Health Organization's expert committee on drug dependence report. People have also had heart problems, depressed breathing, stomach pain, nausea and vomiting.

A 2019 study examining cases reported by poison control centers linked 11 deaths in the U.S. to kratom from 2011 to 2017. Two of those deaths "occurred after exposure to kratom only," the study found.

The CDC reported autopsies of 152 people who died of overdose between July 2016 and December 2017 tested positive for kratom, but the vast majority of those deaths involved people taking multiple substances, including fentanyl, heroin and cocaine.

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Dependence is a risk because kratom has opiate-like effects, said Dr. Alan Kaye, professor of anesthesiology and pharmacology at Louisiana State University in Shreveport.

"You don't have to be a pharmacologist like I am to know that giving out an unregulated opiate agonist can be a problem in terms of abuse, addiction and overdose," Kaye said. "Does that sound like something that should be unregulated and sold at your gas station?"

Is kratom legal?

Kratom is sold as a nutritional supplement, and the FDA can shut down marketers who make therapeutic claims to get consumers to purchase their products. Last decade, the FDA issued two import alerts that allows the agency to seize kratom shipped to the United States as a dietary supplement or bulk ingredient.

The agency has periodically confiscated shipments. Last month, the FDA announced U.S. marshals seized a quarter-million kratom products and 1,000 kilograms of bulk ingredients made by Botanic Tonics LLC in Broken Arrow, Oklahoma. In 2021, federal authorities seized from a Florida manufacturer 34,000 kilograms of bulk kratom and products sold under brand names such as Boosted Kratom, Devil’s Kratom and El Diablo. The FDA secured a court order to destroy the products, which were worth about $1.3 million.

But nine states have passed legislation modeled after the kratom consumer protection act, which includes labeling requirements and restricts sales to minors. Those states are Utah, Georgia, Arizona, Nevada, Oregon, Colorado, Oklahoma, West Virginia and Virginia, according to the American Kratom Association.

Alabama, Arkansas, Wisconsin, Indiana, Vermont and Rhode Island banned kratom products last decade, but the association has petitioned some of those states to reconsider. The association said these states relied on information from the FDA, which unsuccessfully sought to schedule the drug as a narcotic.

Mac Haddow, a senior fellow on public policy at the American Kratom Association, said the industry has tried to self-police by warning manufacturers to avoid therapeutic claims. The association has referred details of more than 75 companies for potentially running afoul of federal rules by making unsupported therapeutic claims, but the FDA hasn't pursued action against those companies, Haddow said.

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Is kratom an opioid substitute?

Though kratom has long been used in Southeast Asia for centuries, the substance has become more popular in the United States over the past two decades. One study estimated 10 million to 16 million Americans regularly use kratom.

NIDA cited studies finding people use kratom to alleviate pain, anxiety and depression. Others use it as a replacement for opioids or to manage withdrawal symptoms.

In one survey of more than 8,000 kratom users, nearly 68% said they used the substance to treat pain and 66% to address emotional or mental conditions.

Haddow cited studies that showed people use kratom to reduce dependence on opioids.

"Others use it like a cup of coffee for energy-boosting or to refocus," Haddow said. "Some people use it to get rid of anxiety or depression symptoms."

Capsules, tea or powder? How kratom is ingested

Though kratom is often sold as pills or capsules in retail stores, some use it as a powder to mix in drinks. Others brew kratom leaves as a tea or ingest in a liquid form.

Because kratom is not regulated, users really don't know how much they are taking.

"It's not standardized, like any drug would be from the FDA," Kaye said. "There can be adulterants, blood concentration to be too low for therapeutic (effect) and there can be side effects and drug interactions."

Kratom and pregnancy: What to know

NIDA reports little research has been done on kratom use before, during or after pregnancy. A 2021 study found at least five cases of babies born with an opioid-like dependency to mothers who used kratom but not opioids.

Still, those who use kratom during pregnancy often use other substances, so "the effects of kratom alone on pregnancy are difficult to determine without further research," NIDA reports.

Is kratom withdrawal a concern?

Early research suggests users experience mild to moderate withdrawal symptoms when they stop regular use, and anonymous surveys of users suggest "a minority of people report experiencing kratom-related withdrawal symptoms," NIDA reports.

Scientists say the main kratom ingredients − mitragynine and 7-hydroxymitragynine − partly activate brain receptors that addictive drugs do.