More than 60 per cent of patients admitted to a Dublin hospital through its emergency department were found in a recent audit to have been exposed to prescription errors.
In some cases there were several prescribing errors per patient.
The study, conducted at St Vincent's hospital, involved a review of medical notes and drug charts, interviews with patients, and a review of laboratory test results.
A total of 53 patients were involved in the study and there were 93 prescribing errors detected in 456 medication orders for these patients, an error rate of 20.4 per cent, or 1.75 errors per person admitted through the emergency department.
The majority of errors - some 86 per cent of them - were related to patients' regular medications. Omission errors accounted for over half of these (56 per cent), with transcription errors (25 per cent) and incorrect prescriptions (18 per cent) accounting for most of the remainder.
The relevant medical team was contacted and informed of each incident detected and the error was subsequently rectified.
When the errors were rated according to their significance, it was found that 18 per cent of them would have resulted in increased length of stay for patients or temporary harm. No permanent harm to patients or deaths resulted.
The study was carried out by Amanda Nevin, a student pharmacist, and supervised by her tutor Niamh O'Hanlon, who said the issue of who exactly made the mistakes was not examined.
As a result of the study, the hospital had decided to appoint a pharmacist to the emergency department.
"What was happening at St Vincent's is no different to any other department in the country - it's just that we decided to audit it," Ms O'Hanlon said.
"There is a message in this for all hospitals," she added.