Antidepressants can help mild to moderate depression and should not just be used in bad cases, researchers say.
Current guidelines urge doctors to avoid antidepressants as an initial treatment in mild depression.
But an NHS-funded study of 200 patients from across England found the drugs, called SSRIs, were more effective than GP advice and support alone.
The team hope national advisers will look at their findings, reported on the Health Technology Assessment website.
Study leader Professor Tony Kendrick, a GP and researcher at the University of Southampton, said although the National Institute of Health and Clinical Excellence wants doctors to restrict SSRIs to the most severe cases, GPs frequently prescribe them for milder cases.
"Just because someone has mild depression does not mean it is a mild illness, because it can cause them to be off work for months," he said.
"And often you don't have psychological treatments to offer because they're not available so you end up prescribing quite frequently."
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