The company that makes Excedrin, NoDoz, Bufferin and Gas-X said Sunday that they are recalling some bottles of those products due to concerns that the bottles could contain stray pills from other medicines, or chipped or broken tablets.

The recall was implemented voluntarily, and the Swiss drug maker says it's working with the Food and Drug Administration.

The company, Novartis, became aware of the potential problem during an internal review that identified broken and chipped pills, and inconsistent bottle packaging that could cause pills to be mixed up. The company said it wanted to make sure that customers didn't take any pills that they might be allergic to or that might become dangerous when mixed with their other medications, though it also said that there have been no such reports from consumers.

Novartis said that some of the bottles of headache medicine Excedrin and caffeine caplets NoDoz with expiration dates of Dec. 20, 2014, or earlier will be subject to the recall.

Some of the packages of pain medicine Bufferin and stomach medicine Gas-X with expiration dates of Dec. 20, 2013, or earlier will also be affected.

The company said it will post more information Monday at www.novartis-otc.com. Customers can also call the company at 1-888-477-2403 Monday to Friday, 7 a.m. to 6 p.m. MST.