It’s been a busy week for authorities going after sham products: a day after the New York Attorney General’s office announced that six companies had agreed to stop selling products that are ineffective at warding off Zika-carrying mosquitoes, the Federal Trade Commission is reminding a slew of businesses marketing Zika-prevention products that it’s illegal to make health claims that simply aren’t true.

The FTC sent 10 warning letters [PDF] to online marketers that have been selling items that are supposed to provide some kind of protection from the Zika virus in an apparent attempt to take advantage of consumer concerns about the mosquito-borne virus.

The FTC warns the undisclosed companies that Zika protection claims have to be supported by actual, competent, reliable scientific evidence. That means well-controlled human clinical testing.

Much like the products the New York AG’s action targeted, the items for sale from these companies include wristbands, patches, and stickers that claim to repel Zika-carrying mosquitoes or otherwise protect users from the virus.

In order to make those kinds of assertions, any testing the businesses would do to prove that must use the same species of mosquito linked to Zika — Aedes aegypti — and demonstrate that the repellant works as long as it says it does.

The letters urge the companies to review the claims that they and their distributors are making, and delete or change them if they don’t have any scientific evidence to back it up.

In addition, the recipients are asked to report back to the FTC within 48 hours, “detailing the specific actions they have taken to remove or change potentially false, misleading, or unsupported claims.”

While it might be nice to slap a botanical patch on your arm and feel like you’re invisible to Zika-carrying mosquitoes, per the Centers for Disease Control, none of those patches, bands, or ultrasonic devices are effective. Instead, consumers should look for repellants containing DEET, Picardin, IR3535, oil of lemon eucalyptus, or para-menthane-diol.

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