Merck & Co., which is already facing a raft of cases over its pain reliever Vioxx, may need to hire additional attorneys to fight a recently filed lawsuit alleging the company was negligent in promoting its osteoporosis drug Fosamax.

According to a lawsuit filed Monday in U.S. District Court in Fort Myers, Fla., Fosamax is a defective product because it can cause osteonecrosis of the jaw, or a rotting of the jaw bone. The suit, which seeks class action status, alleges that Merck concealed and continues to hide Fosamax’s potentially dangerous side effects from patients and doctors.