A review has found 46 children suffered 'significant harm' as a result of mental health care in Co Kerry.
It followed allegations young people were prescribed inappropriate medication by a junior doctor.
Concerns were raised about the care provided by a junior doctor between 2016 and 2020.
He worked for the South Kerry Child and Adolescent Mental Health Services.
There were concerns about 'potentially dangerous' treatment, including over-prescribing and diagnosis.
The HSE ordered a review of over 1,300 files.
It has found 227 children were exposed to the 'risk' of significant harm - with 'clear evidence' of 'significant harm' caused to 46 children.
This included considerable weight gain, sedation during the day, high blood pressure, and the production of breast milk.
13 other children were 'unnecessarily exposed to a risk of harm' under the care of other doctors.
The HSE has sincerely apologised to the young people and their families, and says the 35 recommendations in the report will be implemented as quickly as possible.
Tanaiste Leo Varadkar says there will be a response by government to the report:
"I think there has to be. Our health service is there to make people better and if it's a consequence of failings in our health service - then the people affected and their families need to know what happened and why.
"They also need to be assure they will get whatever medical treatment they need to put things right."