Hospitals have had to share morphine with each other and have considered cancelling surgery because of continuing shortages of essential medicines, a weekend conference heard.
Stocks of tetanus vaccine are also insufficient to meet demand, the annual general meeting of the Hospital Pharmacists' Association Ireland heard.
The situation has worsened because of the "absurd" application of a regulation which has stopped pharmacists importing tetanus vaccine from the UK.
Hospitals are increasingly forced to use unlicensed medicines to cope with shortages, the society's president, Mr Andrew Barber, told the meeting in Dublin.
In some cases the problems are part of a worldwide shortage of medicines.
In others they are due to difficulties being experienced by an Irish company which supplies medicines.
The HPAI is seeking talks with the Department of Health and Children and with the Irish Medicines Board on the issue of shortages and unlicensed medicines.
Mr Barber said shortages have been "so critical in their nature that in a number of centres they led to discussions on the possible cancellation of elective surgery, shortages that also led to some hospitals running dangerously low of morphine injection."
Pharmacists had succeeded in managing the problem "by sharing product amongst colleagues".
There is a worldwide shortage of tetanus vaccine but "a number of us were able to get the vaccine from the UK," he said.
But this supply has been shut off because there was now some licensed Irish tetanus vaccine on the market and regulations stipulated that "you cannot import unlicensed product if licensed product is available in Ireland."
The rule applies even though the amount of Irish vaccine available is insufficient. The rule "makes sense in normal supply conditions, but currently that is far from the case," he said.
"Ask any A/E consultant about their concerns for patients without a clear tetanus vaccination history, having been potentially exposed to this most deadly of micro-organisms."
pomorain@irish-times.ie