The majority of people who were caught driving under the influence of drugs had used cannabis, an analysis of blood samples by Dutch forensic institute NFI has shown.

The institute looked at 64,000 samples taken between 2017 and 2023. Cannabis was found in 71% of cases, followed by amphetamines and ecstasy in 30% of cases. Cocaine and GHB were found in 15% and 6.8% of the samples.

Some 20% of people had used a combination of drugs, such as cannabis and cocaïne, or GBH with amphetamines. The institute also found combinations of three or four different drugs.

“Driving under the influence of drugs is extremely dangerous, not just for the driver but for other road users,” NFI researcher Carolien Boone told broadcaster NOS.

“If you see from an analysis that three or four different drugs have been used, you know that that driver took a huge risk. More than once, the driver in question did not have a driving licence,” she said.

Of the drivers found to be under the influence of drugs, 92% were men with an average age of 29. The cannabinoid THC tended to show up in the blood of suspects below the age of 26,  while cocaine and amphetamines were more often found in older drivers.

Saliva samples have been in use since 2017 and are followed up with a blood test if positive. The number of blood samples analysed by the NFI is increasing year by year. In 2021, police took 4,450 blood samples from suspected drug drivers. In 2025, that number rose to 28,841.

The NFI said its next brief will be to investigate how often drugged driving leads to accidents.