The Food and Drug Administration said several studies showed increased risk of hip, wrist and spine fractures in patients using drugs that block stomach acid.
The drugs are known as proton pump inhibitors and include both prescription drugs like Nexium and over-the-counter medicines like Prilosec.
The FDA says all drugs in the class will carry new warning labels about the potential risk.
"Health care professionals should consider whether a lower dose or shorter duration of therapy would adequately treat the patient's condition," said FDA's Joyce Korvick in a statement.
