In 2015, the U.S. Food & Drug Administration wrote a letter to the manufacturers of UltraCBD, a CBD oil extract shipped across the country and which promoted itself as a miracle cure for a list of ailments including malignant tumors, bacterial infections, lung cancer, and breast cancer.

The letter informed the company that by selling this product, they were violating a number of FDA guidelines, including introducing an untested drug into the marketplace and misbranding a drug.

“Your products are not generally recognized as safe and effective,” it read. “Additionally, your product is offered for conditions that are not amenable to self-diagnosis and treatment by individuals who are not medical practitioners.”

But that wasn’t just good old fashioned cannabis-isn’t-a-medicine federal government talk. The truth is that CBD oil manufacturers, particularly ones who sell online, are not usually selling products which have been screened or tested by the FDA or any other regulating body.

In fact, if a company is willing to ship their CBD oil across state lines, it’s a big tip off that their product might be bogus. While cannabis extract is illegal to ship across state lines, industrial hemp is not. What many companies do to stay mostly within the law is make hemp extract and ship it to consumers across the country. But hemp is not particularly rich in CBD, and to extract that cannabinoid from hemp requires “harsh chemicals,” according to reporting from Leafly.

If you go to the UltraCBD website right now, you’ll see that they call their product a “rich hemp-based extract” and that they now only refer to their oil as a “dietary supplement,” not a medicine. You’ll also find a disclaimer reading, “UltraCBD™ is not currently accepting or fulfilling orders due to the regulatory environment governing hemp based extract.”

Some online CBD oil vendors have shut down following the new drug code designation of cannabis oil last December, but the ones that do have no oversight, meaning they could contain virtually as little CBD and as much contaminants, pesticides, or heavy metals as they like without you knowing.