The Food and Drug Administration has announced a nationwide recall of a batch of alprazolam, a generic version of Xanax, because of potential contamination.

The manufacturer, Mylan Pharmaceuticals, said Friday that the voluntary recall was because of the possible presence of a foreign substance. The company had not received reports of problems related to the tablets, but “the remote risk of infection to a patient cannot be ruled out,” it said. A Mylan spokeswoman did not immediately respond to questions about what the contaminant was.

Alprazolam is prescribed to manage anxiety and panic disorders. The affected batch of 0.5-milligram doses was distributed in the United States in 500-tablet bottles in July and August, with an expiration date of September 2020, the company said.

Image Credit... U.S. Food and Drug Administration

Jeremy Kahn, a spokesman for the F.D.A., said that patients who filled prescriptions for the drug during those months should consult their pharmacist.