Fluticasone propionate, a steroid medication commonly used to treat asthma and allergic rhinitis, was evaluated for its potential as a corrosion inhibitor for API 5L Grade B steel in a 3.5% sodium chloride medium. The experimental techniques employed included the gravimetric method, potentiodynamic polarization, electrochemical impedance spectroscopy measurements, and surface analysis. The results demonstrated that fluticasone propionate is an effective corrosion inhibitor, with inhibition efficiencies of 90.10%, 91.86%, and 92.91% as determined by the weight loss method, polarization studies, and the electrochemical impedance spectroscopy technique, respectively. As the inhibitor concentration was increased in the corrosive solution, the charge transfer resistance also increased, due to the growing thickness of the electrical double layer. Polarization data indicated that the drug acted as a mixed-type inhibitor. Adsorption studies confirmed that the adsorption process was spontaneous and involved a physisorption mechanism: adsorption of the drug compounds onto the metal surface followed the Langmuir adsorption isotherm model. An increase in the electrolyte temperature led to a decrease in the inhibition efficiency from 90.10% to 72.45%. A thermodynamic analysis revealed that the addition of the inhibitor led to an increase in the activation energy of the test solution from 6.06 kJ.mol^-1 to 31.04 kJ.mol^-1, thus confirming the formation of a protective layer that reduced the kinetics of the corrosion reactions. Surface analysis revealed that the inhibited sample showed less deterioration compared to the uninhibited one.