Corrosion is a critical industrial problem. To solve this problem, the present research analyzed the influence of corrosive media on the efficiency of a guayusa inhibitor. Therefore, guayusa extract was obtained, and five groups of ASTMS A36 steel test tubes were prepared, each with variable extract concentrations (200 ppm, 400 ppm, 600 ppm, 800 ppm, and 1000 ppm) that were exposed to different corrosive media (5% NaCl, 5% NaCl + acetic acid, 1% HNO₃, and 10% HNO₃). The results obtained were compared to determine the percentage efficiency of the inhibitor in each of the corrosive media. This study provides a detailed understanding of how the corrosive environment influences the effectiveness of a guayusa inhibitor, which is used as a green inhibitor for the first time, allowing its viability and performance to be assessed under various conditions.