There were over 30 cases of people caught driving with four different drugs in their system last year.
The most common combination was cannabis, cocaine, benodiazepines and heroin.
In total, the Medical Bureau of Road Safety found over 1,200 cases of people driving under the influence of at least two drugs last year.
Leo Lieghio, from the Irish Road Victims Association, says courts need to issue tougher sentences.
