More than one in seven (16%) young drivers admit to having driven after taking drugs, a survey has found.
Two-thirds (66%) of those who had done so said they had got behind the wheel after smoking cannabis, with cocaine (24%), ecstasy (16%) and heroin (8%) also being used.
Some 14% of drivers aged 25 to 34 said they were likely to drive after taking drugs over the festive period.
More than 2,000 UK drivers were questioned for the poll, which was commissioned by law firm Slater and Gordon.
Paul Reddy, a road traffic defence lawyer at the firm, said: "The festive season is a time for good cheer but all too often I see lives ruined because people have a few drinks or take drugs before getting behind the wheel.
"Despite constant education campaigns and stories in the media, motorists are still caught out.
"If you don't want to lose your licence, or worse still injure yourself or innocent people, don't take the risk."
A Department for Transport spokesman said: "Thanks to our tougher law, more dangerous drivers are being caught and convicted.
"Driving under the influence of drugs is extremely dangerous; it can lead to tragedies that devastate families and ruin lives. Drug drivers face a minimum 12-month driving ban, an unlimited fine and can even go to prison.
"The Government stands shoulder-to-shoulder with police as they work tirelessly to protect the public and we have carried out a THINK! road safety campaign to help change attitudes."