The FDA is cracking down on delta-8 THC, the legal-ish weed that gets you high and is being sold openly all over the US

• The FDA issued its first warning letters to companies selling delta-8 THC, a compound derived from cannabis.
• Delta-8 THC gives users a similar high to the main psychoactive ingredient in marijuana.

The US Food and Drug Administration issued its first warning to makers of products containing delta-8 THC, a cannabis compound that induces a "high" but falls within a legal loophole in the US.

Delta-8 THC is a compound closely related to delta-9 THC, the main psychoactive ingredient that gives marijuana users a high. It can be derived from a similar part of the marijuana plant as CBD, a non-psychoactive compound, and that is part of the reason why it falls into a legal gray area.

Businesses are openly selling the product online, in stores, and in cafes, and some brands make health claims that delta-8 can alleviate sleeping disorders or reduce anxiety.

But the FDA said in a statement issued Wednesday that there is very little research on delta-8, and there are "no FDA-approved drugs containing delta-8 THC" that can diagnose, cure, or treat diseases.

The FDA issued five warning letters to companies making unapproved claims about delta-8 as a treatment for medical conditions, and for misbranding products by not including "adequate directions for use." The companies are ATLRx Inc., BioMD Plus LLC, Delta 8 Hemp, Kingdom Harvest LLC, M Six Labs Inc.

"The FDA is very concerned about the growing popularity of delta-8 THC products being sold online and in stores nationwide," FDA principal deputy commissioner Janet Woodcock said in a statement.

The FDA also said on Wednesday the agency has received reports of hospitalization and trips to the emergency room after some users took delta-8 THC. National poison control centers said calls of poison exposure involving products containing delta-THC ational poison control centers have increased, the FDA said, but the agency did not specify a time period.

Delta-8 is less potent than the most commonly known THC, but it still gets you high

Delta-8 has between half to three-quarters the level of potency as delta-9, but cannabis specialists and users said the compound can make users feel relaxed, clear-headed, and giggly.

Delta-8 skirts federal regulation due to a loophole in the 2018 Farm Bill, which removed hemp with low levels of delta-9 THC from classifying as a controlled substance and did not explicitly mention delta-8.

Scant research exists on delta-8 THC's effect on the body and brain. "What we do see about it are little keys to its vast potential, but we don't really know because there haven't been that many studies," Peter Grinspoon, a primary care physician at Harvard Medical School, told Inverse Magazine.