People are being warned to never take drugs or have a drink and drive.
The warning comes from the Road Safety Authority and Gardaí this bank holiday weekend.
Last year 125 people were arrested for DUIs over the Easter bank holiday.
This is also the first weekend Gardaí can do roadside tests for drugs.
Denis Cusack from the Medical Bureau for Road Safety says with drugs, it's hard to know when they are out of your system.
"There are a lot of people that say 'I've had a few pints a few hours ago it's not affecting me'.
"You know, just like drink of course it can stay in the system and we would recommend that certainly not within 24 hours, because the problem is - unlike drink where you have an idea of what you might have taken - the difficulty with cannabis what's coming in, you've no idea of the strength it could even be different to what a person has taken a week before or a day before," he said.