Given that the adulteration of dietary products with unauthorized content of erectile dysfunction drugs has increased in the world, public health is threatened worldwide. The illegal use of these drugs poses serious health risks to consumers and the environment. The contents of dietary supplements and environmental samples should be monitored carefully in order to control the abuse of erectile dysfunction drugs. Therefore, a sensitive and selective method was developed for the simultaneous determination of sildenafil and tadalafil using LC-QTOF-MS/MS. The chromatographic separation was successfully achieved. The analysis was performed with an electrospray ionization mass spectrometer through the targeted MS/MS mode within 4.0 min. Calibration plots for both analytes were linear with correlation coefficients greater than 0.9992 within the range of 0.50-2000 ng/g. LOD/LOQ values were calculated as 0.16/0.53 and 0.28/0.93 ng/g for sildenafil and tadalafil, respectively. The validated assay was successfully applied to energy drink, tap water and sewage sludge samples. The quantitative measurements were performed on seventeen different brands of energy drinks and the results were compared with the written ingredients on the bottles. The tap water and sewage sludge samples were also analyzed and the recovery values were calculated for sildenafil and tadalafil.