All lots of Pfizer Inc’s anti-smoking treatment Chantix have been recalled after the discovery of high levels of cancer-causing agents in the pills, reports Reuters.

Pfizer had already recalled some lots of Chantix and halted the distribution of the drug back in June and has now asked wholesalers and distributors to completely halt the use and distribution of the pills with immediate effect, according to Reuters.
Chantix, which was approved by the FDA in 2006, is a prescription drug that helps adults to quit smoking and is used for 12 to 24 weeks on average. Patients currently using the drug are advised to contact their health care provider and switch to alternative treatments although Pfizer has stated there is no immediate risks to patients taking Chantix.