It may take anywhere between 2-3 weeks to 4-6 weeks for Bupropion to kick in, but the somatic symptoms may take a shorter amount of time to go away, compared to the depressed mood and lack of interest in activities, which may subside after some time. If there is no improvement in any of the symptoms for up to 4-6 weeks, it may mean that the bupropion is not working, and either the dosage needs to be increased or the doctor might ant to explore the idea of some other medication.