U.S. health officials Thursday asked drugmaker Pfizer to stop selling the painkiller Bextra because of concerns that the risks of using the drug outweigh the benefits.

The drug is used by millions of people, particularly those who suffer from arthritis.

Pfizer, which is the world's largest drug manufacturer, agreed to suspend sales in the United States and European Union.

U.S. officials also asked makers of drugs similar to Bextra to put labels on their packages warning of possible cardiovascular and gastrointestinal problems linked to the drugs.

Regulators have been studying the safety of a whole class of drugs called "Cox-2 inhibitors" since drug maker Merck pulled the painkiller Vioxx off the market last year.

Some information for this report provided by AFP, AP, and Reuters.