WASHINGTON – Check your medicine cabinet: Millions of bottles of the widely used pain reliever acetaminophen – some sold as long as three years ago – are being recalled because they may contain metal fragments.

The recall affects 11 million bottles containing varying quantities of 500-milligram acetaminophen caplets made by the Perrigo Co. The pills were sold under store brands by Wal-Mart, CVS, Safeway and more than 120 other major retailers, the Food and Drug Administration said. At least one chain started pulling the pills from store shelves Thursday.

There were no immediate reports of injuries or illness. The contaminated pills included metal fragments ranging in size from “microdots” to portions of wire one-third of an inch long, the FDA said. The FDA could not describe further the type of metal.

Perrigo discovered the metal bits during quality-control checks done after the company discovered its equipment was wearing down prematurely, the FDA said. Agency officials declined to say whether the metal found in the pills caused the damage or resulted from it.

A company investigation turned up metal in roughly 200 pills of the 70 million it passed through a metal detector, according to the FDA.

Consumers who take any of the contaminated pills could suffer minor stomach discomfort or possible cuts to the mouth and throat, the FDA said, adding that the risk of serious injury was remote. Anyone who suspects they have been injured should contact a doctor.

Acetaminophen is best known as the drug in products sold under the Tylenol brand, but is widely available in typically less expensive generic versions. The drug, along with aspirin and ibuprofen, is one of the most widely used pain relievers available without a doctor’s note.

The retail market for the pain relievers is worth more than $2 billion a year, according to Perrigo, which bills itself as the world’s largest manufacturer of store-brand nonprescription drugs.

Kevin Vincent, 44, of Arlington, Va., said his wife buys store brand acetaminophen and he wanted to find out more about the problem.

“If it’s not something that has any chance of recurring, then I really wouldn’t worry,” he said.

The 129 retailers that could potentially be affected by the recall include Wal-Mart Stores Inc., CVS Corp., Safeway Stores and SuperValu Inc. They typically sell the Perrigo-made pills under their own or other private labels.

CVS will stop selling its own brand of 500-milligram acetaminophen caplets and pull bottles from store shelves nationwide, spokesman Mike DeAngelis said. Messages left with the other chains were not immediately returned.

Perrigo, based in Allegan, Mich., said the pills contained raw material purchased from a third-party supplier and affected 383 batches. Messages left with two company spokesmen were not immediately returned.

The FDA declined to identify the source of the raw materials. However, the agency doesn’t suspect the contamination was deliberate, said Dr. Douglas Throckmorton, deputy director of the FDA’s Center for Drug Evaluation and Research.

Molly Walsh, 21, a George Washington University student shopping at a CVS pharmacy in Washington, D.C., said she didn’t plan to toss any of the store-brand drugs at home that she’d bought to save money. Nor did she plan to stop buying the generic products.

“It’s still going to be cheaper and I’m still going to be broke after the recall,” Walsh said.

The recall does not affect Tylenol, nor should the recall cause a shortage of acetaminophen, the FDA said.