The U.S. Food and Drug Administration warned against misleading ads by eight surgical centers and a marketing firm.

By failing to provide the required side effects and surgical risk information about Lap-Band procedures – and in a font size big enough to be legible – the firms face penalties and inventory seizure, the FDA said.

Allergan, Inc.’s Lap-Band is considered a restricted medical device. The procedure involves surgically inserting an inflatable gastric band at the top of the stomach to reduce stomach capacity. It is approved to help obese patients lose weight when methods such as diet and exercise fail. More than a third of American adults are obese.

Risks of the Lap-Band procedure include infection, nausea, vomiting and irritation of the esophagus.

The centers receiving the FDA’s warning were Bakersfield Surgery Institute, Inc., Beverly Hills Surgery Center, Palmdale Ambulatory Center, Valley Surgical Center, Top Surgeons LLC, Valencia Ambulatory Center LLC, Cosmopolitan Plastic & Reconstructive Surgery and San Diego Ambulatory Center LLC, and 1-800-GET-THIN.