Abstract Background: The recent coronavirus disease 2019 (COVID-19) pandemic has strongly affected the young population, with a significant impact on their mental health, lifestyle, and sleep. The aim of the present study was to explore the effects of COVID-19 on oral health and general hygiene habits in an undergraduate medical school population. Methods: A total of 500 participants, including pre-graduate students from the School of Medicine with a mean age of 22.84 ± 2.68 years completed an anonymous web survey. Of these, 200 belonged to the schools of dental hygiene and dentistry and 300 belonged to the medical school. Results: Students suffered from increased stress and emotional distress, which led to an increase in weight in 48.6% of the subjects. A reduction in personal and dental hygiene (8% and 4%, respectively) was observed. Students in dentistry and dental hygiene courses were more careful about their dental hygiene. Students from the dentistry and dental hygiene courses reported an increase in the use of chlorhexidine mouthwash during quarantine (+ 15%). Conclusion: Pandemic-related stress has affected the youth, with an increase in unhealthy lifestyle and changes in dental hygiene habits. Strong action must be taken to promote good oral hygiene habits and a healthy lifestyle among the general population during the COVID-19 pandemic.