Packaging problems at a drug manufacturing plant may have resulted in powerful prescription painkillers ending up in packages of Excedrin, NoDoz, Bufferin and Gas-X Prevention.

Novartis announced a recall of the over-the-counter products yesterday, citing customer complaints about chipped and broken pills. That notice did not mention any concern that prescription painkillers might have been mixed into bottles of over-the-counter drugs.

But at a news conference today, a senior FDA official told reporters, "There is the potential risk that could happen."

The concern was prompted by an FDA inspection last month of a plant in Lincoln, Neb., operated by Endo Pharmaceuticals, which produces drugs for Novartis Consumer Health. That inspection turned up evidence of three product mix-ups since 2009.

The FDA today warned doctors, pharmacists and patients that certain prescription painkillers made by Novartis may have mistakenly ended up in bottles of other prescription painkillers or with over-the-counter products packaged on the same lines.

Dr. Edward Cox, a director at the FDA's Center for Drug Evaluation and Research, said the agency has received some complaints but has no reports of people getting sick from Novartis products.

"We think the risk of this product mix-up occurring is low," Cox said.