Austrian researchers collected data on more than 1300 patients, 200 of them in the UK, over a 24-hour period.
Of the 441 patients affected, seven suffered permanent harm and five died partly because of the error, the British Medical Journal reported.
Medical staff often cited stress and tiredness as contributing factors.
Data was collected by researchers from Rudolfstiftung Hospital from a total of 113 intensive care units, of which 17 were in the UK.
Nearly half of the affected patients suffered more than one mistake during the period covered. The most frequent errors were related to the wrong time of administration and missing doses altogether. Cases of incorrect doses and wrong drugs being given were also reported.
A total of 69% of the errors occurred during routine care.
Mistakes occurred with many types of drugs, including insulin for diabetics, sedatives and blood-clotting drugs. The doctors and nurses who took part in the study cited stress and tiredness as a contributing factor in a third of mistakes.
Recent changes in the drug's name, poor communication between staff and violation of protocols were also mentioned.
The odds of an error being made increased significantly for the most severely ill patients. Researchers said this reflected the complexity of their care.
