The U.S. Food and Drug Administration is warning about a potential mixup between powerful prescription pain drugs and over-the-counter medications such as Excedrin and Gas-X manufactured at a Novartis plant.

The concern stems from major problems at a Lincoln, Neb., facility that was shut down last month. The Swiss drugmaker has recalled bottles of Excedrin, Bufferin and other medications that may have included mixed up pills. Medications like Excedrin may have accidentally been packaged with powerful prescription painkillers in the U.S.Medications like Excedrin may have accidentally been packaged with powerful prescription painkillers in the U.S. (Mark Lennihan/Associated Press)

Some of those over-the-counter pills may have accidentally been packaged with powerful prescription painkillers made at the same facility, the FDA says. The opioid drugs are sold by Endo Pharmaceuticals as Percocet, Endocet, Opana and Zydone.

FDA officials say they are not recalling the drugs because they are medically necessary and the likelihood that they contain stray pills is low.

The products were not sold in Canada, Novartis said.