The smoking cessation drug Chantix was found to have no link to psychiatric problems, a report from the Food and Drug Administration says.

In a drug safety notice released Monday, the FDA said two epidemiological studies failed to find an increase in the risk of psychiatric side effects with Chantix use.

A number of previous reports suggested that some of side effects of Chantix included suicidal behavior, sudden violent outbursts, depression and other psychological problems.

“Although these two studies did not suggest an increased risk of neuropsychiatric events that result in hospitalization, they do not rule out an increased risk of other neuropsychiatric events with Chantix,” the FDA concluded.

Study results are based on a comparison of the rate of psychological problems suffered by Chantix users that resulted in hospitalization to those linked to other stop-smoking methods like nicotine patches. The agency said it would continue to evaluate the psychological risk factors of Chantix.

The FDA approved the use of Chantix in 2006 to reduce the positive feelings associated with cigarette smoking. Pfizer, the creator of Chantix, has a patent for Chantix that expires in 2018. At that time, a generic version of the drug could go on the market.

Pfizer is currently being sued by several individuals that claim the drug caused serious injury or death from suicide attempts or unusually aggressive behavior.