What is antidepressant withdrawal syndrome? Antidepressant withdrawal syndrome can occur after selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) are stopped abruptly or tapered too quickly. Withdrawal reactions typically begin within hours to days of decreasing the medication and do not represent a recurrence of the underlying depression. Withdrawal reactions tend to be more likely at the end of the taper when patients are almost off the medication. Prozac substitutionIf an individual still experiences withdrawal symptoms, another strategy involving the transient addition of the long-acting antidepressant fluoxetine can be implemented.