The Food and Drug Administration (FDA) of the United States of America has issued warning letters to 18 websites accused of marketing counterfeit or unapproved botulinum-toxin products—widely associated with the brand Botox—for cosmetic use. The agency flagged the action after receiving reports of adverse events, including toxic effects, linked to products purchased online.

Botulinum toxin treatments, approved for cosmetic and medical applications, carry the FDA’s most serious “boxed warning” because they can cause life-threatening muscle weakness, including impaired breathing and swallowing.

According to the FDA’s announcement, the offending websites promoted versions of botulinum toxin that are unauthorized and misbranded. The regulator said these online vendors may offer products that are counterfeit, improperly stored or transported, or otherwise unsafe for use. The agency emphasized that consumers should only receive botulinum-toxin injections from licensed health-care professionals using approved products, and should seek immediate medical attention if they experience symptoms of botulism—such as difficulty swallowing or breathing—after injection.

The crackdown underscores growing concern about the proliferation of illicit injectable products circulating via the internet. For patients and consumers, the FDA’s message is clear: appearances can be deceptive, and saving money by buying unvetted drugs online can come at a grave risk.