The U.S. Food and Drug Administration (FDA) has recalled thousands of bottles of antidepressants nationwide.

These bottles contained levels of a potentially carcinogenic chemical.

Newsweek reports how the antidepressant in question – duloxetine delayed-release capsules, marketed under the name Cymbalta – was initially recalled on October 10. The recall has since been upgraded to Class II, defined by the FDA as “a situation in which use of or exposure to an infringing product may result in temporary or medically reversible adverse health consequences, when the likelihood of serious adverse health consequences is low.

The Cleveland Clinic reports how the drug is used to treat depression, anxiety, fibromyalgia, and certain types of chronic pain. Other brands include Drizalma and Irenka.

According to the FDA, 7,107 vials of Duloxetine had levels of N-nitroso-duloxetine that exceeded the acceptable limit set by the administration.

The same Newsweek article explains that this chemical belongs to a group commonly found in water and food products called nitrosamines. However, if individuals are exposed to higher concentrations for a prolonged period of time, they could increase the risk of developing cancer.

“There are multiple reasons why nitrosamines may be present in medications,” the FDA said in a statement. “(The) FDA has found that the source of nitrosamines may be related to the drug’s manufacturing process or its chemical structure or even the conditions in which they are stored or packaged.

“As foods and medications are processed in the body, nitrosamines can also be formed. (The) FDA continues to test and research possible sources of drugs containing nitrosamines.

The FDA noted that – although the antidepressant has been recalled – those who have been prescribed the drug should consult their doctor before stopping using it.

The investigation into the cause of the impurities found in delayed-release Duloxetine is still ongoing.