The world's largest study into the effectiveness of antidepressants has shown that the drugs really do work.

Trials of 21 commonly used antidepressants showed that each one was more effective than placebo pills in relieving acute depression in adults.

The meta-analysis used results from almost 120,000 patients across 522 trials.

Image: The most and least effective antidepressants were revealed

However, despite the positive outcome of antidepressants overall, the study found large variations in the level of efficacy and side effects caused by each pill.

The most effective drug was amitriptyline - a drug first discovered in the 1950s.


One of the least effective pills was fluoxetine - a selective serotonin reuptake inhibitor (SSRI) commonly known as Prozac.

Research leader Andrea Cipriani of Oxford University struck a note of caution, warning that antidepressants will not work for everyone. About one third of depressed patients do not respond to such medication.

Mr Cipriani added that the findings do not mean that antidepressants should always be the first line of treatment.

Image: Around 300 million people worldwide suffer from depression

Other options include talking therapies such as cognitive behavioural therapy and counselling.

It is hoped that the study, which is published in The Lancet medical journal, will help both doctors and patients to make informed decisions about the best medication to take.

Some 300 million people suffer from depression worldwide according to the World Health Organisation, with just one in six people in rich countries getting effective treatment.

That figure drops to one in 27 patients in poor and middle-income countries.

Recent studies indicate that 10% of British adults now take antidepressants, with these findings suggesting that millions more could benefit from the drugs.

Image: So which antidepressants are the most effective?

Most effective antidepressants:

Agomelatine

Amitriptyline

Escitalopram

Mirtazapine

Paroxetine

Venlafaxine

Vortioxetine

Least effective antidepressants:

Fluoxetine (widely known as Prozac)

Fluvoxamine

Reboxetine

Trazodone