Background: The contribution of the pharmacist in influencing health behaviours and raising awareness of the impact of self-medication (SM) is valuable. During the COVID-19 pandemic, SM was triggered by multiple factors driven by the fear of becoming infected. This study aimed to identify the determinants of SM during the outbreak, with a focus on the role of social media, and to determine areas where the active contribution of the pharmacist needs strengthening. Methods: A pilot cross-sectional study using snowball sampling was conducted in thirteen countries. Results: A total of 2369 participants with a mean age of 30.62±11.57 years were enrolled in the study. The determinants of SM were 1) sociodemographic characteristics, including developing countries (ORa= 0.670; 95%CI [0.49, 0.91]); 2) communication channels, where Facebook was the most used social media platform (ORa=1.624; 95%CI [1.29, 2.05]); and 3) content and sources of unverified information, i.e. television interviews (ORa=1.357; 95%CI [1.03, 1.78]) and videos with someone confirming the effectiveness of medication used (ORa=1.353; 95%CI [1.06, 1.73]). The perceived risk severity was associated with elderly polypharmacy (ORa= 2.468; 95%CI [1.87, 3.26]). Conclusion: The pharmacist should collaboratively and actively contribute to the design and implementation of health promotion programmes and convert to positive the influence of social media.