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 two chains – CVS Corp. and SuperValu Inc. – 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.

Acetaminophen is best known as the drug in products sold under the Tylenol brand. But it is available in typically less expensive generic versions.

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