Pfizer has recalled batches of Chantix, its anti-smoking drug. The drug contained an increased amount of cancer-causing impurities.

Included in the nationwide recall are two lots of Chantix 0.5mg Tablets, two lots of Chantix 1 mg Tablets, and eight lots of a Chantix kit of 0.5mg/1 mg Tablets, the drug manufacturer announced on Friday. The nationwide recall includes two lots each of Chantix 0.5mg Tablets and two lots of Chantix 1-mg Tablets. Eight lots of Chantix kits of 0.5mg/1mg Tablets were also included, according to , the drug manufacturer.

The recall announcement stated that all were “due the presence of a nitrosamine or N-nitrosovarenicline above the Pfizer established Acceptable daily Intake (ADI level).

They stated that while long-term N-nitrosovarenicline ingestion may increase the risk of cancer in some people, there is no immediate danger to patients who take this medication. “The potential cancer risk from varenicline nitrosamine impurity outweighs the health benefits of quitting smoking.”

According to the FDA, everyone has been exposed at some point to nitrosamines. These chemicals are found in food and water. The FDA warns that nitrosamine impurities can increase cancer risk if they are used at higher levels than acceptable and for long periods.

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FDA issued an update Friday recommending that patients who were prescribed drugs affected by the recall should “continue to take their current medication until their pharmacist or doctor provides a substitute or prescribes a new medication.”

FDA stated that agency scientists assessed the risk of N-nitrosovarenicline exposure at interim acceptable intake levels of 185 ng/day and found minimal additional cancer risk compared to lifetime exposure at 37 ng/day.