How long does it take for Wellbutrin to work for anxiety? How long does Wellbutrin take to work? Certain anxiety symptoms, such as those associated with depression or smoking cessation, may improve from Wellbutrin within one or two weeks of starting the prescription. However, full remission of symptoms may not take place for up to eight weeks. Go to: https://www.medsengage.com/blog/how-long-does-it-take-for-wellbutrin-to-work/