The U.S. Food and Drug Administration (FDA) this week announced that it is “taking action” to remove illegal diabetes treatments from store shelves. The agency has sent letters to 15 companies, notifying them that their products illegal.

“The FDA is committed to protecting consumers from the dangers of these illegally sold products,” said Howard Sklamberg, director of the Office of Compliance in the FDA’s Center for Drug Evaluation and Research. “We will continue to take aggressive action against firms that sell illegal products claiming to treat diabetes.”

According to the FDA, the products include those labeled as dietary supplements that claim to “mitigate, treat, cure, or prevent diabetes and related complications.” Also included are products sold as “natural” diabetes treatments with undeclared active ingredients, homeopathic products claiming to treat diabetes complications, and prescription drugs sold prescription-free by online pharmacies.

The FDA is advising that Americans avoid using such products, as they could be unsafe or marketed improperly.

“Diabetes is a serious chronic condition that should be properly managed using safe and effective FDA-approved treatments,” said Dr. Margaret Hamburg, FDA commissioner. “Consumers who buy violative products that claim to be treatments are not only putting themselves at risk but also may not be seeking necessary medical attention, which could affect their diabetes management.”