The use of substances such as cigarettes, khat, alcohol, and other illicit drugs like hashish, heroine, cannabis, and cocaine is a global major public threat, which affects young adult people particularly in developing countries [1–3]. Drug uses disorders and ill-health-related conditions are major public health problems. Worldwide, it is estimated that alcohol and illicit drugs accounted for 5.4% and 3.7% of the global burden of disease in 2009, respectively [4]. It is also estimated that 9% of the world population aged 12 or older are classified with dependence on psychoactive substances such as alcohol [5].

The United Nations in 2014 indicated globally, alcohol consumption accounts for about 5.9% or nearly 3.3 million deaths of the global deaths, and 5.1% of the global burden of disease and injury were attributable to alcohol consumption in 2012 [6]. Early start of drinking increases the likelihood of alcohol-related injuries, motor vehicles crashes involvement, unprotected intercourse, and interpersonal violence. Alcohol uses also to contribute to youth suicides, homicides, and fatal injuries [7].

The most locally produced and highly consumed alcohols in Ethiopia are tella, areque (katikala), shamita, tej, and borde. Aside from locally fermented alcohols beers, gin, wine, and other alcoholic liquors are widely used alcohols products [8]. The Ethiopian public health association (EPHA) in 2007 reported that about 30.5% of adolescents aged 15–24 in Ethiopia ever used substances in their life, while young adults seem to be the most involved in alcohol and khat consumption than any other population group [9]. A similar study based on the 2005 behavioral surveillance surveys have reported that males are more likely to use substances than females, but the trends for the habits of using substances is rising from time to time among females [10]. The Ethiopian Demographic and Health Survey 2016 reported the prevalence of alcohol use among men and women is 46% and 35%, respectively, and 27% of men and 12% of women ever chewed khat [11].

Previous studies showed that peer pressure, accessibility, cultural accessibility, parental involvement, and low self esteem are the major reasons for starting using substances in Ethiopia, while some adolescents use substances to relax, and to avoid or forget their problems and anxieties, like problems arising from economic stress [12].

A cross-sectional study conducted on substance uses and associated factors among Haramaya university students indicated that more than 62% of students use at least one substance, 50.2% use alcohol, 41% chewed khat in their lifetime, 23.6% currently use khat, while 22% were using cigarettes at least once in their lifetime, 10.8% currently smoke cigarette and 7.4% used illicit drug like hashish [13]. A systematic review and meta-analysis on substance use among adolescents aged 10–19 years in sub-Saharan Africa between 2000 and 2016 revealed the prevalence of substance use ranged from 37% in South Africa to 55.5% in central Africa with the overall prevalence of substance use 41.6%. About 32.8% uses alcohol, 23.5% uses cigarette, 22% use khat, and 15.9% use cannabis [14].

Wakgari and Aklilu studied substance use and its predictors among undergraduate medical students of Addis Ababa University in Ethiopia, the study reported 22% of students used alcohol, 7% used khat, and 9% of students use cigarette [15]. A similar study conducted in Debre Birhan University reported 36.3% of the lifetime use of alcohol, 10.9% lifetime use of khat, and 7.4% lifetime use of cigarette among students, while 4.2% and 4.5% of students were used shisha and cannabis, respectively, in their lifetime. Further, the study reported 17%, 5.7%, and 3.1% of students are currently using alcohol, khat, and cigarette, respectively [16]. Shimelis and Wosen in their study on causes, prevalence, and consequences of alcohol and drug abuse among Mekelle University students reported the prevalence of alcohol and drug abuse among students is 30% and the major reason for alcohol and drug abuse are peer pressure, psychological factors, academic factors, and social factors [17].

A study conducted in Nepal reported, 6% prevalence of substance use among high-school adolescents [18]. A similar study in the Southeast Asian nations reported that the lifetime prevalence of illicit drug uses was 16.9% [19].

Another study conducted in Gondar University showed 62.9% prevalence of drug uses and the major contributing factors of substance uses are relations, increase performance, and peer pressure [20]. While Gobeje et al. [21] in their studies about the prevalence of substance use and associated factors among preparatory students of Woldia Town, northeast Ethiopia, in 2015 found that the overall prevalence of substance use is 34.6%, whereas 23.5% of students chewed khat and use cigarettes. A multidomain factor analysis studies conducted in Woreta Town found 47.9% prevalence of current substance uses and 65.4% prevalence of lifetime substance use among high-school adolescents in Woreta Town [22]. Similarly, a study done on prevalence of substance abuses among University students in Tigray, northern Ethiopia, reported 43.9% of university students abuse substances [23].

In Harar, eastern Ethiopia, Reda [24] found a 12.2% prevalence of cigarette smoking among school adolescents. While, the Drug Administration and Control Authority in 2005 found 10.1%–11.5% prevalence of a lifetime smoking and 3%–5.6% current prevalence of cigarette smoking among high-school adolescents in Addis Ababa [25].

Exposure to sexually explicit materials (SEM) means a picture, photograph, drawing, sculpture, motion picture film, or similar visual representation which is obscene for children. Pornography and SEM will be used interchangeably. Webster's dictionary defines pornography as “the depiction of erotic behavior intended to cause sexual excitement.” Exposure to sexually explicit materials stands viewing sexually explicit material through media such as the Internet, videos, and magazines that may be directly linked with the sexual behavior of adolescents and young adults. Globally, adolescents spend more time with the media than they do in school or with their parents [26]. Much of what young people are listening to and/or watching includes sexual content. Males have been found to be more likely to expose themselves to SEMs than females. In Ethiopia, youths aged 15–24 years were more than 15.2 million, contributing to 20.6% of the whole population [27]. These large and productive groups of the population are exposed to various sexual and reproductive health risks. Among many sexual and reproductive health risks, sexual coercion, early marriage, polygamy, unplanned pregnancies, closely spaced pregnancies, abortion, and sexually transmitted infections (STIs) are the major ones [28].

Risk and protective factors for youth substance abuse should be assessed as a prevention program as they help decrease unhealthy behavior [29, 30]. Individual protective factors, such as engagement in positive meaningful activities, positive self-concept, and religious or spiritual beliefs (religiosity) inhibit adolescent substance use. Peer protective factors, such as positive peer role models [31] also reduce adolescent substance use. Family factors that are found to be protective for adolescent substance use are connected to family (attachment/bonding), positive parenting style, living in a two parent family, higher parent education, and higher parental expectations about school. School protective factors include being connected to school (attachment/bonding), and caring school climate, and community protective factors are connected to other positive adults (bonded/attached), safe, supportive, connected neighborhoods, and community rewards for prosocial involvement [32].

Uses of substance and its consequence is one of the recent problems aggravate adolescents. The sustainable development goal (SDG) indicator, 3.5 targeted to strengthen the prevention and treatment of substance abuse, including narcotic drug abuse and harmful use of alcohol by the year 2030 [33].

Despite the fact that a number of researches have been done on substance uses, nowadays in Ethiopia many adolescent students and young adults migrate from rural to urban areas to attend secondary and higher educations or in search of job. This will in turn relate to risky sexual behavior. The prevalence of substance uses and exposure to risky sexual behavior is still high, and more effort is needed to minimize the rate of substance use and exposure to sexually risky materials. The finding of this study will help for the development of preventive policies, effective intervention priorities, and any cost benefit analysis-related substance abuse and exposure to SEM. It will contribute to the literature by highlighting the influential characteristics of substance abuse and exposure to SEM by various social, economic, cultural, and demographic factors. It could also be part of baseline information for policy makers. Therefore, the main objective of this study is to assess the prevalence and associated factors of substance use and exposure to sexually explicit materials among high-school adolescents in North Shewa zone of Oromia regional state, Ethiopia (Figures 1 and 2).