HOUSTON (KXAN) — A lawyer is suing convenience stores near Houston, claiming they sell Viagra disguised as an over-the-counter supplement.

Attorney Robert Tauler has sued 15 Shell convenience stores in the area after a number of his clients have ended up in the hospital after using pills marketed as being able to improve sexual performance, CNN affiliate KTRK reports. Tauler claims the pills actually contain the main ingredient in Viagra, a drug that requires a prescription from a doctor to purchase.

“We have had people that have suffered very serious emergency surgeries and requiring penile replacement surgeries,” Tauler said. 

The convenience stores named in the lawsuit have not commented on the case.

Pills like the ones sold at some gas stations aren’t regulated by the Food and Drug Administration because they’re technically classified as dietary supplements. Tauler says they’re created overseas and sold under different names, one of which is “Rhino” brand.

“That’s all they do is change the name because they know that’s how they can beat federal law enforcement for now,” Tauler said. “And that’s where we step in. We’re civil enforcement.”

Doctors told KTRK consumers may not know what they are putting in their bodies, and that the pills could potentially interfere with other medications. They say people who are having issues should talk to their doctors and come up with a plan to address them.