Background: COVID-19 is a worldwide public health concern. Disruptions in the drug market are expected and shortages might worsen. Community pharmacies can contribute to early identification and report of medicines' supply and demand issues. Objective: The aim of this study is to characterize the impact of the COVID-19 outbreak on outpatient medicines' sales and shortages. Methods: A retrospective, time-trend analysis of medicine sales, shortages and laboratory-confirmed COVID-19 cases was performed from February 1st to April 30th, 2020, and its homologous period (regarding sales only). A detailed analysis of 6 pharmaceutical substances was performed. All data were subjected to rescaling using the min-max normalization method, in order to become comparable. Data analysis was performed using Microsoft® Excel. Results: The pandemic resulted in an increase in medicines' demand and reported shortages during the early stage of the outbreak. The maximum proportion of medicine sales was registered on March 13th, 2020, 4 days after the WHO declared COVID-19 a pandemic. By the end of March, sales have already dropped to proportions similar to those of 2019. The maximum proportion of drug shortages was reached about one week after the sales peak and by the end of the study period were below those recorded in the pre-COVID-19 period. The analyzed drugs were paracetamol, ascorbic acid, dapagliflozin plus metformin, rosuvastatin plus ezetimibe, formoterol, and hydroxychloroquine, as these pharmaceutical substances registered the highest growth rate in sales and shortages when compared to the same period in the previous year. Hydroxychloroquine showed the most different pattern trends on sales and shortages of these medicines. Conclusions: Pharmacies can provide timely and real-world data regarding sales and shortages. The adopted measures to guarantee the continuous supply of the medicine market seem to have worked. The long-term impacts of this pandemic are unknown and should continue to be closely monitored.