A few Fosamax users have experienced osteonecrosis of the jaw or jaw death, a condition in which jawbone tissue breaks down exposing underlying bone. Infections, gum lesions, and loosened teeth can result. Dental surgery seems to provoke jaw osteonecrosis in Fosamax users.
Fosamax has also produced the side effects joint and muscle pain, atrial fibrillation (irregular heartbeat), and esophageal inflammation or ulcers.
Because of bone fracture and other side effects, many Fosamax users have filed lawsuits.