Treatment with SSRIs rather than placebo was associated with clinical improvement by the end of the first week of use .
CONCLUSIONS Treatment with SSRIs is associated with symptomatic improvement in depression by the end of the first week of use , and the improvement continues at a decreasing rate for at least 6 weeks
CONTEXT Selective serotonin reuptake inhibitors ( SSRIs ) are often described as having a delayed onset of effect in the treatment of depression .
However , some trials have reported clinical improvement as early as the first week of treatment .
OBJECTIVE To test the alternative hypotheses of delayed vs early onset of antidepressant action with SSRIs in patients with unipolar depression .
A study comparing paroxetine placebo and imipramine in depressed patients.
These data provide evidence for the antidepressant efficacy of paroxetine . Paroxetine- and imipramine-treated patients were significantly different from  placebo-treated patients , but little different to each other , on all depressive outcome measures . However , paroxetine appeared to have a possibly greater and earlier beneficial effect on anxiety symptoms associated with depression , when compared with imipramine . Both active therapies were effective in treating patients with severe depression . Side effects for paroxetine were typical of other serotonin ( 5-HT ) uptake inhibitors but different from those of imipramine . In particular , anticholinergic and cardiovascular symptoms were reduced , and premature withdrawal less likely
Treatment with SSRIs rather than placebo was associated with clinical improvement by the end of the first week of use .
CONCLUSIONS Treatment with SSRIs is associated with symptomatic improvement in depression by the end of the first week of use , and the improvement continues at a decreasing rate for at least 6 weeks
CONTEXT Selective serotonin reuptake inhibitors ( SSRIs ) are often described as having a delayed onset of effect in the treatment of depression .
However , some trials have reported clinical improvement as early as the first week of treatment .
OBJECTIVE To test the alternative hypotheses of delayed vs early onset of antidepressant action with SSRIs in patients with unipolar depression .