In quality control labs, Paracetamol (PAR) and ibuprofen (IBU) are mostly found in the same-party combination tablets, and separating both quickly in parallel labs demands smart methods. This work is about the invention and the analysis of a very simple method of first order UV-visible spectrophotometry and derivative validation for both PAR and IBU in combination tablets. The different order spectra of both drugs in 0.1 NaOH were combined, and then spectra were manipulated by first order shift to explain the absorption line overlaps. The method exhibited a standard line from 4 to 24 and from 3 to 18 for PAR and IBU, respectively. Correlation coefficients of 0.9992 and 0.9990 are the highest. The intra-day and inter-day precision studies showed relative standard deviation (%RSD) values lower than 1.5%, and the mean recovery values were between 99.0% and 101.2% for both analytes. The analysis showed the detection limits to be 0.8 and 0.7 µg/mL for PAR and IBU, respectively, with quantification limits of 2.4 and 2.1 µg/mL, respectively. IBU-PAR tablets showed labeled claims within 98%-102%. Overall, the proposed method is reliable, simple and affordable for routine preclinical tests of the mentioned analytes.