A unit of Johnson & Johnson announced a nationwide recall on Thursday of all lots  more than 13 million packages  of the soft chewable versions of Rolaids, its popular antacid drug, after reports of consumers finding metal and wood particles in the products.

The unit, McNeil Consumer Healthcare, has been troubled by manufacturing deficiencies over the last year, which has led to a series of recalls of some of the country’s most popular over-the-counter brands. A recall in April alone involved about 136 million bottles of liquid children’s Tylenol and other pediatric products.

Although McNeil said early this year that it was instituting a comprehensive plan to improve its manufacturing and quality control systems  including the temporary closure of a plant in Pennsylvania for an upgrade  some manufacturing problems have continued.

The foreign particles found in the Rolaids were potentially introduced during production at a third-party manufacturer, McNeil said in a statement. McNeil declined to identify the manufacturer.