Or the opposite. The ramp-up period (4-8 weeks before the brain rebalances its chemistry in response to the drug) is hell, and cessation of the drug (or running out without access to a pharmacy) causes near-total loss of cognitive ability for a few days (with brain zaps to boot).
That's why I'm not using my bupropion. I got a prescription last month to treat seasonal affective disorder, and my psychiatrist wants me to use it every winter then cycle off in the spring, but the side effects both coming on and off seem awful.