A study carried out as part of the Count 14 campaign indicated almost three-quarters (72 per cent) of people in Scotland were unable to identify the correct units in beers, wines and spirits.
It found just over a third (36 per cent) correctly said there are two units in a pint of beer while less than a third (29 per cent) identified a medium glass of wine having two units.
Just 18 per cent of respondents knew the one-unit content of a single measure of spirits.
Dr Catherine Calderwood highlighted the concerns following the campaign launched recently to raise awareness of the guidance that states men and women should drink no more than 14 units a week.
She said: “With insight pointing towards unit confusion amongst Scots, we’re keen to reinforce what 14 units looks like in terms of alcoholic drinks.
“The 14-unit guideline equates to six pints of medium strength beer, lager or cider, seven double measures of spirits or six medium glasses of wine over the course of a week.
“By continuing to raise awareness of alcohol units, the hope is that people will make informed choices when drinking at home or in the pub, and reduce the risk of harm.”
The unit guidelines were revised in 2016 and suggest those who regularly drink 14 units per week should spread it over three days or more, with some alcohol-free days.
Figures last year revealed Scots bought enough alcohol for every adult to drink nearly 20 units per week.
ScotRail also tweeted a message urging against alcohol-related anti-social behaviour ahead of the holiday weekend.