Seven out of 10 children with serious mental health problems are being treated outside their home area, according to NHS figures.
Around 69% of young patients were admitted to hospitals away from their local region in 2016/17, up from 57% the year before, an investigation by the British Medical Association (BMA) has found.
Dr Gary Wannan, the BMA's community care committee chairman, said it is alarming that more children and teenagers are being treated away from their homes when they are "at their most vulnerable".
"It can be an incredible wrench for children to leave their homes and being based far away is not going to help a young person in crisis," he said.
"In some areas we have seen the rate of investment improve so patients don't have to be treated so far from home - in other areas, patients haven't been so fortunate.
"NHS England must ensure that, especially in these areas, the money gets through to local community teams so they can make a real difference to the lives of children, young people and their families."
The figures were obtained from NHS England in a Freedom of Information request by BMA News.