The use of psychoactive substances by adolescents at school is a major global public health problem.^1,2 The prevalence of substance abuse has been reported to be on the rise in countries throughout the world such as Iran and Brazil and also in some African countries such as Nigeria, Ghana and Ethiopia.^3,4,5 Because adolescence is a period of risk-taking, young people often place high value on particular behaviours that are peer approved, even if they may be risky and impact negatively on their well-being.⁶ Although the substance of choice used by learners may not be similar in all areas, there are some substances that are common at a global scale, and these include alcohol, cigarette, dagga or marijuana or cannabis and cocaine.⁷

South Africa has a high prevalence of risky alcohol use for men, women and even young people. Alcohol can be easily purchased at bottle stores, supermarkets, bars, shebeens and other unlicensed liquor outlets, which outnumber licensed ones especially in disadvantaged communities.⁸

The high prevalence of substance use in South Africa is a major concern for public health because it carries significant health risks. It also contributes to social problems such as crime and violence, with learners who use substances being more likely to experience violent acts and being involved in criminal activities.^1,3 Learners who use substances often experience injuries in road accidents and fights, which are sometimes fatal. Substance use is also associated with risky sexual behaviours, scholastic problems like dropping out of school, and physical and mental health problems that include depressive symptoms.⁷

Substance use carries significant health risks to learners and increases both morbidity and mortality. Blood-borne infections such as hepatitis C and HIV have been reported to be common amongst people who use injectable drugs.⁹ Substance use also contributes to risky sexual behaviour because sexual inhibition is negatively affected by the effects of the substances used.⁶ They would also be more responsive to the approval they will get from their peers than they would be sensitive to the effects a hangover or the ill effects of a drug reaction that they might have. Their capacity for judgement and self-control is still not fully developed; hence their decision-making becomes risky.⁶ Substance use, therefore, contributes to high costs of health care as people using drugs need health care services as a direct result of their substance use.

Although the use and abuse of substances amongst high school learners in South Africa are acknowledged, the extent of this public health problem in various areas of the country is not known; hence this study focussed on studying this phenomenon in a specific surbub of Johannesburg.

A total of 400 questionnaires were distributed to potential participants during data collection, and 308 (77.0%) had complete data for analysis. Their ages ranged from 13 to 21, with a mean of 16.3 and a median of 16 (SD 1.5). For analysis purposes, the ages were categorised according to the developmental phases of early teens (13–15), middle teens (16–18) and early youth (19–21). As shown in Table 1, 57% of learners were females and 43% males. The participants were in grades 8–12, with the junior phase (grades 8–9) at 19.2% (n = 59) and the senior phase (grades 10–12) in the majority at 80.8% (n = 249). The majority (73%) of the learners were Black, and Christian learners were in the majority at 82.7%. Nine per cent of the parents were unemployed, 57% of fathers and 75% of mothers had acquired secondary and tertiary education. The majority (70%) had fewer than 3 children in their family.

The results of the study show a high prevalence of substance use by high school learners in this sample, which included both male and female learners across all grades of high school. The results confirmed a high prevalence of substance use for both genders, with the use of alcohol, cigarettes and dagga being the most commonly used substances. Although the use of substances was found to be below 50% of the total sample, the prevalence for male use of dagga and cigarettes was high at above 50% of those that use substances, whilst female use of alcohol was 51%.

These findings were similar to a study conducted in a different area of Johannesburg, which found a higher prevalence amongst males,¹⁰ whilst some studies show males to be twice more likely to use substances than females.^11,12 However, the prevalence of substance use amongst males and females in this study was almost the same, which is similar to previous studies which found a small difference between male and female substance use prevalence.^13,14 This difference is explained by reports of increase in both the frequency and amount of consumption by females.¹⁵

The high prevalence of substance abuse in this sample raises public health concerns as substance use and abuse carry significant health risks⁷ for this sample of young people in school. This is because the learners, who are in the adolescence phase, are at a time of greatest risk taking and often place high value on any reward they get from taking risks, if such actions are acknowledged and approved by their peers.⁶ These risks include social problems such as accidents and injury, violence, crime, high-risk sexual behaviour and poor social relations.¹¹ Academic risks include repeating a grade, missing school because of illness or other reasons, school dropout and low academic aspirations.⁷ Substance use, especially alcohol, is associated with negative impacts on school work like absenteeism, low performance, truancy and delinquency.¹⁶ In this sample, reported impacts were serious problems with friends, having sex without a condom and trouble with the police.

The results also confirm the significant impact of peer pressure, which is the desire by adolescents to fit in and be socially accepted by their peers because they have a high value for the opinion of their peers.^8,16,17 In this study, the use of substances by friends was associated with substance use. This suggests that for some young people, the need for approval may surpass reasoning and compliance with other values of the family or school.

The most commonly used substances by the high school learners included alcohol, which was followed by cigarettes and dagga, and the least used substances being ecstasy and inhalants. These findings are similar to others, which found that the most commonly used substances by adolescents in South Africa include alcohol, cigarettes and dagga.^7,18,19 The trend is similar globally, and alcohol, cigarette and dagga are amongst the most common substances of abuse by adolescents at school.^4,5,20,21 The common use of these three substances can be explained by their ease of access, that it is more socially acceptable to use alcohol and cigarette and that dagga is easy to grow. Other studies found that alcohol is the most abused drug, with ease of access being the main contributory factor.^8,21,22,23 This was confirmed by the results of this study, which identified alcohol as the most used substance by the majority of those who use substances. Alcohol is reported to be attractive to young people because it is seen as a sign of maturity and it is easily accessible.²⁴

The results of the study supported previous reports that adolescents start using substances at an early age of between 13 and 15 (Table 4), which is similar to findings from previous studies that found the mean age of initiation to be between 13 and 14 years.^4,14,15,25 The early initiation of substance use comes with a variety of negative health and social outcomes.²²

The findings of this study identify the social environment as influential in substance abuse, which indicates a need to target groups rather than the individual for interventions aimed at preventing substance use. Moreover, the experiences of physical and psychological discomforts such as stress, low self-confidence and being overwhelmed by challenges experienced in their lives, which are often cited as drivers to substance use, also affect their peers, families or even society at large.^17,24 As a social environment, on one the hand the school system influences adolescents against the use of drugs, often through the use of rules, whilst on the other hand, the influence of other learners can succeed in planting a rebellious and negative influence against the school system. It is for that reason careful and well thought out interventions should be developed in an effort to prevent substance abuse amongst learners in a school environment, which learners often use as a means to escape painful experiences of failure of various types.²⁴

This study found that almost half (46.2%) of the learners who use substances tried to quit, which is similar to another study conducted in a rural area of South Africa, where it was found that learners often try but fail to quit the use of substances.¹³ This indicates that some substance using young people realise the risk of using substances but fail to quit because addiction has set in. Their attempt and failure to quit is one criterion that qualifies their use of substances to be viewed as abuse.²⁶

The study found that the majority of learners who do not use substances cited personal choice and parental guidance, which is encouraging as it confirms that family values still have a role in discouraging risky behaviours. The cited reasons give an indication of areas to focus on, when interventions for prevention of substance abuse are developed and implemented.

Although the response rate was high at 77%, 23% of the questionnaires had missing data of more than 10% each and could therefore not be included in the analysis. Their inclusion could have given a clearer picture of substance use in this sample.

The use of substances by learners seems to be a new norm in South Africa, with resultant negative impacts on their physical, social and academic life. The common use of cannabis and alcohol, which is illegal for minors, indicates criminal behaviour which needs to be addressed. The study also found a higher prevalence of alcohol amongst female learners, which is increasingly being reported, and calls for more studies to investigate contributory factors to this phenomenon as well as identify protective factors within the communities to counteract this behaviour.