Eli Lilly & Co. is stepping up its fight against a booming black market for retatrutide, an experimental drug that the company is counting on to expand its crucial weight-loss franchise.

For almost two years, Lilly has been warning consumers not to take knockoff versions of the shot that are being sold online and at wellness clinics and medical spas. It hasn’t been approved by regulators anywhere in the world.

Now, Lilly is upping the pressure. The drugmaker filed a handful of lawsuits against US businesses, many in Texas, that sell retatrutide products illegally. It’s also asking regulators to do more to rein in the illicit market. The lawsuits cite customer complaints and social media advertisements.

One business, Lilly said, offered a calculator to help people figure out what dosage of retatrutide they should be taking. That’s typically done by a licensed doctor.

Businesses that enable and facilitate the sales — including credit card companies, shipping firms and social media sites — also have a role to play in protecting consumers, Lilly said, calling it an “urgent public health crisis.”