Purpose: To describe Brazilians’ behavior regarding face mask use and health literacy during the COVID-19 pandemic before and after the Ministry of Health of Brazil formal recommendation. Design: Cross-sectional surveys using a web-based questionnaire. Participants were recruited via snowball techniques. Setting: São Paulo state, the urban epicenter of the COVID-19 pandemic in Brazil at the time of the study. Participants: 2.203 clicks to the survey link and 1.223 surveys completed (55.5% response rate). However, only 1118 surveys were considered after the exclusion criteria (>18 years-old and consent). Measures: Demographics, educational status, COVID-19-related symptoms (headache, cough, sore throat, rhinorrhea, fever, asthenia, diarrhea, dyspnea, nausea, vomiting, vertigo, anosmia, and ageusia), and face mask use. Analysis: Self-reports of COVID-19 symptoms were categorized as dichotomous variables (Cohen’s h = 0.94). Pearson Chi-square test evaluated differences between T1 and T2 and logistic multiple regression analyzed odds-ratio for the presence of symptoms and independent variables. Results: Face mask use increased from 43.60% in T1 to 90.52% in T2 ( P < .0001) as the pandemic went on. Health literacy also changed within 2 weeks and people started to assume everybody should use face masks (62.93% in T1 vs 94.12% in T2; P < .0001; ES = 0.29) during outside activities (43.60% in T1 vs 90.52% in T2; P < .0001; ES = 0.39). Self-reports of face mask use were associated with fewer self-reports of COVID-19 symptoms (OR = 0.65, P = .01, 95% CI 0.48; 0.88). Conclusion: Face mask use was already high among educated Brazilians before the formal recommendation by the authorities. This may have contributed to fewer self-reports of COVID-19-related symptoms.