More than 70,000 children, including nearly 2,000 of primary-school age, were prescribed antidepressants in England last year.
The pills were handed out in large numbers despite warnings that they may harm developing brains for little benefit.
Antidepressants rarely work in children, according to experts, with one saying that doctors were “medicalising adolescence”.
NHS figures released to The Times show that one in six adults in England – 7.3m – used antidepressants last year – a rise of almost half a million in three years.
And as the number of prescriptions is rising, after more than doubling in a decade, antidepressants are increasingly becoming a long-term support among the population.
Some 1,844 children aged under 10 are taking the drugs, the figures show.
And more than half a million people aged 18-24 were given antidepressants last year, 11 per cent of the age group.
But the over-60s are twice as likely as those in their twenties to be on the drugs.
There are also big regional variations, with places such as Blackpool and Great Yarmouth showing high usage – one in five people – whereas in London it is fewer than one in 10.
Mental-health campaigners say access to other treatments, such as “talking therapies”, should be made more widely and easily available as a first resort.
Andrea Cipriani, a psychiatrist at Oxford University, told the paper: “These are very, very high figures.
“People are prescribing antidepressants to those who don’t really need them, who have low mood.
“It’s important people are aware that antidepressants aren’t a quick fix.”
He added: “We should be careful of prescribing antidepressants to the developing brain. We don’t know the long-term consequences.”
In 2016 a review by Dr Cipriani found most antidepressants did not help children and teenagers with serious mental-health problems and some could even be unsafe.
The review of evidence from 34 trials found that of 14 such drugs, only one, Prozac, was better than a placebo at treating young people with major depression.
Another drug, venlafaxine, was associated with an increased risk of suicidal thoughts and suicide attempts.
But his study concluded that the real effectiveness and safety of antidepressants for children and teenagers was unclear because of the poor design and selective reporting of trials, mostly funded by drug companies.
Dr Cipriani said that “nowadays the risk is medicalising adolescence” with drugs.
A high number were prescribed in south Lincolnshire, the figures showed. “It’s difficult to justify. There must be something wrong,” he said.
The figures were obtained under freedom of information laws from the NHS business services authority.