Consumers may find some cold and flu medications to be in short supply this winter, as a manufacturing plant belonging to drug maker Novartis remains closed for “maintenance and improvements.”

The company voluntarily recalled a number of its products in the United States in January and closed its manufacturing facility in Lincoln, Nebraska for work “at the site to ensure our products meet the highest quality standards.”

The shutdown followed a report by the U.S. Food and Drug Administration expressing concern over quality-control systems at the plant, including evidence that some batches of medication included tablets or caplets of other drugs produced at the plant.

In a statement, the company said that in January, it recalled drugs such as Excedrin, Bufferin and Gax-X in the U.S., “because the products may potentially have contained stray tablets or broken or chipped tablets.”

Health Canada also issued a recall for some Excedrin products.

The company assured consumers of the safety of its products.

Novartis also, “voluntarily suspended operations at and shipments from our Lincoln, Nebraska facility,” which has led to supply disruptions on both sides of the border.

Products that consumers may have difficulty finding as cold and flu season begins include NeoCitran, Otrivin, Triaminic and Buckley’s. Other drugs include Benefibre, Excedrin, Maalox and Slow Fe.

“We are working as quickly as we can to return these products back on to store shelves,” the company said Wednesday in a statement.

“We appreciate the patience and loyalty of our consumers and retail partners, and sincerely apologize for any inconvenience the absence of these products has caused.”

The company said it is “using a combination of Novartis and third party manufacturing facilities” in an effort to get products back onto store shelves.