More than 36% have had a drink or used drugs just one or two hours before starting their shift, according to the unique poll.
Cannabis, cocaine and ecstasy as well as alcohol were the substances most commonly taken. The finding is just one of a number of insights provided by the world's largest drugs survey, involving tens of thousands of people, which has published results for Scotland for the first time today.
Well over half (58%) of those who completed the questionnaire in Scotland recorded potentially harmful drinking habits and were at increased risk of liver disease, stomach ulcers, high blood pressure and other health problems.
Dr Evelyn Gillan, chief executive of Alcohol Focus Scotland, said: "The Global Drugs Survey highlights, once again, that alcohol is the drug of choice in Scotland."
In total, 631 people from Scotland completed the Global Drugs Survey which aims to provide a snapshot of what drugs are being used and how they are having an impact. Of these 7.2%, had such high scores for alcohol use, it suggested they were addicted. Many of these drinkers were not aware they had a serious problem - one-third thought their consumption was average.
Adam Winstock, consultant psychiatrist and addiction specialist behind the survey, said: "The thing that is most damning is how clueless people are. The higher the drinker, the more deluded you become."
The percentage of dependent drinkers in Scotland was the third highest out of the 15 countries in the survey, only falling behind the Republic of Ireland and Belgium.
Dr Winstock added: "There is a beautiful sense of everyone else is drinking like me and it is just OK. The thing that changes people's behaviour is whether they think what they are doing is abnormal or places them at risk and why would you possibly think about changing your behaviour if there is no reason to. That is the challenge for public health. How do you get people to wake up to the fact that your behaviour isn't like everyone else?"
Many Scottish drinkers did take measures to moderate their drinking. Just over one-third said they usually alternated alcoholic drinks with water, 87% eat before starting to drink and 81% have at least two alcohol-free days a week. Most said taking these precautions did not reduce the pleasure of drinking.
Dr Winstock, a senior lecturer at King's College London, and his team are releasing a potentially controversial "user's guide to safe and more enjoyable drug use" based on their survey findings from around the world this week.
More than 70% of Scottish respondents told the survey they had been hungover at work - similar to the finding for the UK as a whole - but a higher proportion than most other countries involved. One-quarter of participants in Scotland had used drugs including alcohol within four to 12 hours of starting work in the past year, and a further 26% had done so at some point.
Dr Gillan said a culture had developed where "excessive drinking has become the norm rather than the exception".
She added: "Being in work under the influence of alcohol or hungover can directly impact on workplace productivity and safety. Heavy drinking can have a long-term effect on employee work performance, including sickness absence, inefficiency, poor decision-making and damaged customer relations."
A Scottish Government spokesman said: "We are well aware of this issue, with an average of almost 700 people admitted to hospital every week due to alcohol."