Addiction to smartphone is defined as the disability to cease using the device despite the physical, psychological, or social consequences. The diagnosis of this disorder is increasing exponentially among teenagers, even more so after Corona Virus Disease 2019 (COVID-19) pandemic. This study aims to analyze the risk of mobile phone addiction among teenagers in Italy and its relationship with other risk behaviors, such as drug consumption and emotional well-being, following the COVID-19 pandemic. A cross-sectional observational study was conducted in Catania, Sicily, during 2022. The study sample comprised 342 students from a secondary education center that answered to a validated Italian version of the Smartphone Addiction Scale Short Version (SAS-SV) accessing through computers and mobile devices. Subjective Wellbeing was measured with the Personal Wellbeing Index-School Children (PWI-SC). Also, they completed the NIAAA Brief Alcohol Use Screener. Our results showed that 30.1% of students who participated in the survey were classified with a smartphone addiction. Besides, most of the participants used the Smartphone for social networks (86.0%). Regarding the other aspects measured, the mean self-perceived well-being score measured with the PWI-SC was 55.5, and 36.2% of participants were categorized as "high risk" for depression. Finally, four out of ten participants were at "moderate or high risk" of an alcohol use disorder. Our results suggest that the use of mobile phones is increasing in adolescents, an age group also exposed to social and health problems.