The Food and Drug Administration (FDA) has determined the smoking cessation drug Chantix (varenicline) is no more likely than nicotine patches to cause psychiatric events that require hospitalization.

The FDA drew its conclusions after reviewing two studies comparing Chantix to nicotine replacement therapy, including nicotine patches. The agency acknowledged the studies had limitations and will keep the “black box” warning labels on Chantix to advise about possible psychiatric side effects, including changes in behavior, hostility, agitation, depressed mood and suicidal thoughts or actions, Reuters reports.

“Overall, FDA has determined that the current warnings in the Chantix drug label, based on postmarketing surveillance reports, remain appropriate,” the FDA said in a statement.

One study conducted by the Department of Veterans Affairs compared 14,131 veterans using Chantix with an equal number of veterans who used nicotine patches. A second study conducted by the Department of Defense compared almost 20,000 people using Chantix with about 16,000 people who used nicotine patches for a month after they began treatment to quit smoking.

The manufacturer of Chantix, Pfizer, is conducting a large safety clinical trial of the drug to assess psychiatric side effects. Results are expected in 2017.

In June, the FDA said Chantix may be associated with a small, increased risk of certain heart problems in patients with heart disease.