The Marijuana industry received a stern warning from the U.S. government on Tuesday. A threatening letter sent from the Food and Drug Administration (FDA) to four online cannabis sellers demanded cancer-curing claims be removed from products.

The companies that received the FDA letter sell health supplements containing cannabidiol (CBD), a component of the marijuana plant that does not cause the infamous mind-altering effect.

While the marijuana companies are not breaking any drug laws, they are prohibited from making statements that imply their products cure or treat a disease, according to the FDA’s warning.

The cannabis companies involved in the FDA clampdown include Greenroads Health, Natural Alchemist, That’s Natural!, and Stanley Brothers Social Enterprises. Now that they have been notified, they must comply with the FDA letter within 15 days.

The FDA is serious about CBD products

In a recent statement, FDA Commissioner Scott Gottlieb reinforced the agency’s stance on the unsubstantiated health claims made by CBD product manufacturers.

The FDA “will not look the other way” as companies “deliberately prey on sick people,” he said, per a report from the Chicago Tribune.

Are you really getting what you pay for?

While some companies may be making unconfirmed claims about the health benefits of cannabis products, a study published in the Journal of the American Medical Association found a majority of CBD supplements are mislabeled. Professor Marcel Bonn-Miller, with the University of Pennsylvania, tested 84 CBD products and discovered nearly 70 percent did not have the correct amount of CBD as stated on the package. Of the total, 26 percent contained less CBD, while 43 percent contained more.

Interestingly, the inaccuracy often related to the type of CBD product.

Nearly 50 percent of the CBD extract oils were labeled wrong and 90 percent of vaporization liquids were inaccurate. Researchers also found THC, the compound in cannabis that gets someone high, in 18 of the products sampled. Individuals consuming THC, especially without knowing, could get some unwanted side effects such as insomnia and reduction in cognitive abilities. In addition, someone would likely fail a drug test and not know why.

Buyer beware

Under current law, the FDA does not regulate any plant derivatives, including CBD extracts. When buying health supplements, cannabis or otherwise, it is important to buy products from a reputable supplier. If the benefits sound too good to be true, they probably are.