Girls were admitted to hospital for self-harming nearly twice as regularly last year compared to two decades ago, figures have revealed.
The NSPCC described the statistics as "heartbreaking", while an expert suggested social media could have contributed to the rise.
NHS data shows girls were admitted to hospital 7,327 times in 1997, compared to 13,463 times in 2017.
A corresponding rise was not seen in boys, with the figures showing 2,236 admissions in 1997 compared to 2,332 last year.
An NSPCC spokesperson said: "These heart-breaking figures are sadly unsurprising. We know from contacts to Childline that many children are being driven to self-harm as a way of dealing with the pressures and demands of modern-day life.
"Young people are crying out for help and more needs to be done to prevent them from reaching crisis point.
"A key step in this process is ensuring every child and young person feels confident they will be supported when they do speak up so they don't end up trapped in a vicious cycle where they believe hurting themselves is the only solution."
The NSPCC said it gave 15,376 counselling sessions about self-harm last year, the equivalent to 42 per day.
Jon Goldin, the Royal College of Psychiatrists' child and adolescent faculty vice-chairman, told The Times a range of factors including exams and social media are applying pressure to young children.
"If you look at social media, my hunch is that girls are probably more sensitive to some of those factors than boys," he added when asked why the rise was only seen in girls.
A Department of Health spokesman said an extra £300 million will be invested to provide extra help in schools, including training staff to support children faster.
The NHS figures were recently released by a health minister in response to a parliamentary question.
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