The HSE has published a damning report into the care of 1,300 young people who attended South Kerry Child and Adolescent Mental Health Services (CAMHS).
46 of the attendees suffered what the HSE has described as "significant harm."
240 young people received care that fell short of the required standards.
The "significant harm" includes weight gain, elevated blood pressure, the production of breast milk and sedation.
Published today, the report was sent to the families of the children in question, with the HSE issuing an apology to those affected.
"We have sincerely apologised to the 46 young people and their families, and we wish to repeat this apology publicly today," the HSE said. "HSE officials and clinicians offered meetings to all 240 of the young people who did not receive the care they should have. We have apologised in writing to those affected, we apologised in person at meetings and today we sincerely repeat this apology. We opened an information line in April for young people and their families on 1800 742 800. The current opening hours are 8am to 8pm seven days a week."
The report is the culmination of a review headed by Dr Seán Maskey, a London based consultant child and adolescent psychiatrist.
Maskey's findings include "unreliable diagnoses, inappropriate prescriptions and poor monitoring of treatment and potential adverse effects."
Chief Officer of Cork Kerry Community Healthcare, Michael Fitzgerald, commissioned the report.
"Young people and their families are entitled to expect a high standard of care when they attend our services, and the report makes it clear that this did not happen in a large number of cases," he said. "As Chief Officer of the organisation, I apologise sincerely to the young people and their families for this. I want to reassure the young people and their families that we have taken on board the 35 recommendations in the report, and will implement them as quickly as we can."