Thousands of bottles of a popular antidepressant are being recalled because they contain what the National Library of Medicine describes as a toxic chemical, according to a statement from the U.S. Food and Drug Administration.

The recall involves the drug duloxetine, sold under the brand name Cymbalta, according to the FDA's notice of voluntary recall, which began Oct. 10.

Duloxetine belongs to a class of drugs known as SNRIs, or selective serotonin/norepinephrine reuptake inhibitors, used to treat anxiety, depression, and other mood disorders, according to the FDA.

Here are three things consumers should know about the recall.

1. How do I know if my medication is affected by the recall?

According to the FDA, the recall affects 7,101 bottles of duloxetine extended-release capsules distributed nationwide in the United States.

The recalled capsules have a strength of 20 mg and are sold in bottles of 500.

The lot number of the recalled capsules is 220128, with an expiration date of December 2024, the FDA notice said.

The recalled capsules are manufactured by Towa Pharmaceutical Europe.

In an emailed statement, Towa Pharmaceutical Europe referred ABC News to the FDA's website on nitrosamine impurities in medications. N-nitrosoduloxetine is a type of nitrosamine.

“With regard to nitrosamine impurities in medications, the FDA continues to say that patients taking prescription medications with potential nitrosamine impurities should not stop taking their medications. “Patients should speak to their healthcare professional about concerns and other treatment options,” Towa Pharmaceutical Europe said in a statement. “The FDA has also stated that it is working to determine the source of these contaminants and keep the public informed.”

2. What potentially toxic chemical triggered the recall?

The recalled duloxetine capsules were found to contain higher levels of N-nitroso-duloxetine than permitted, the recall notice said.

N-nitrosoduloxetine is a chemical compound that can be toxic if swallowed in elevated concentrations and is suspected of possibly causing cancer, according to the U.S. National Library of Medicine.

The FDA has classified the voluntary recall of duloxetine bottles as a Class II recall. The agency defines this as “a situation in which use of or contact with a violating product may cause temporary or medically reversible adverse health consequences, or in which the likelihood of serious adverse health consequences is low.”

3. What do I do if my medication is part of the recall?

The FDA's voluntary recall notice does not provide specific instructions for handling recalled duloxetine capsules.

Because of the potential risk of side effects, a person should consult their doctor before suddenly stopping or changing the administration of an antidepressant.

Editor's note: This report has been updated to include a statement from Towa Pharmaceutical Europe.