The results, published in The Lancet, suggest that at least one million more people in the UK could benefit from antidepressant treatment.
Further informationView antidepressant drug records
Lead researcher Dr Andrea Cipriani, from the University of Oxford, said: 'This study is the final answer to a long-standing controversy about whether anti-depressants work for depression'.
'We found the most commonly prescribed anti-depressants work for moderate to severe depression and I think this is very good news for patients and clinicians.'
Differences in efficacy
The meta-analysis, which involved unpublished data in addition to information from the 522 clinical trials involving the short-term treatment of acute depression in adults, revealed substantial differences in efficacy between drugs.
Treatments ranged from being a third more effective than a placebo (in the case of reboxetine, a noradrenaline reuptake inhibitor) to more than twice as effective (in the case of the tricyclic antidepressant amitriptyline).
Overall, escitalopram, mirtazapine, paroxetine, agomelatine, and sertraline had a relatively higher response and lower dropout rate than the other antidepressants. By contrast, reboxetine, trazodone, and fluvoxamine were associated with generally inferior efficacy and acceptability profiles compared with the other antidepressants.
The authors said their findings could help doctors to pick the right prescription, although they did not mean all patients' medication should be switched. That is because the study looked at the average effect of drugs and the results do not show which drug would be likely to work best for any one individual.
Most of the data in the meta-analysis covered eight weeks of treatment, so the findings might not apply to longer-term use. The researchers also said it did not mean that antidepressants should always be the first form of treatment.
'Medication should always be considered alongside other options, such as psychological therapies, where these are available,' said Dr Cipriani.
'This meta-analysis finally puts to bed the controversy on antidepressants, clearly showing that these drugs do work in lifting mood and helping most people with depression,' said Professor Carmine Pariante, from the Royal College of Psychiatrists.
'Importantly, the paper analyses unpublished data held by pharmaceutical companies, and shows that the funding of studies by these companies does not influence the result.'