Forty-nine per cent of 3,148 students in grades 7, 9, 10 and 12 told researchers they used alcohol in 2012, while 34.7 per cent used cannabis.
Twenty-seven per cent of the students aged 12 to 19 said they used alcohol, and 14.2 per cent said they used cannabis, more than once a month.
Of those students who took the survey, almost one in five said they seriously considered suicide in 2012.
The survey released Thursday found 19.7 per cent seriously considered suicide in 2012; 11.6 per cent made a plan on how to attempt suicide; and 8.4 per cent tried to kill themselves one or more times.
The chief of the department of psychiatry at the IWK Health Centre in Halifax said the findings on the number of adolescents who considered suicide shows it is important for parents to communicate with their children.
"When there is an active relationship between a teen and his or her parents, the youth has a safety net," said Dr. Kathleen Pajer. "When things get tough, the teen will then be more likely to feel that the parent can help."
In a news release, the provincial government described some of the results as encouraging, such as finding that more than 43 per cent of those surveyed had not used any of the substances included in the questionnaire.
The average age of those adolescents who tried cannabis for the first time was 14.3 years, up from 13.5 years the last time the survey was done in 2007.
Among the survey's findings, cigarette smoking declined. It dropped to 13.2 per cent last year, down from 16.2 per cent five years earlier.
The survey says its findings on smoking are compatible with a study by the University of Waterloo that showed from 1999 to 2010, the largest decline in smokers was among those aged 15 to 19.
"This observed decline in smoking prevalence is felt to be associated with an array of measures taken to prevent and stop smoking, most importantly steadily increasing tobacco taxes, making all indoor public places smoke free and increasing restrictions on tobacco advertising," says the survey.
The survey found that five per cent of those students who responded used cough or cold medicine to get high, 4.7 per cent used ecstasy and 4.1 per cent used cocaine or crack.
For the first time, the survey also asked about the use of energy drinks, and found that almost two-thirds of students reported consuming caffeinated energy drinks.
The researchers from Dalhousie University who conducted the survey say it was done in 176 randomly selected classes in 75 schools throughout Nova Scotia.