In this study, we evaluated the adulteration of glucocorticoids, anorexics as well as hypnotic-sedatives in food products that claim to have medicinal effects and/or are assigned to specific category of drugs. The possible addition of drugs in food was also investigated. The TLC method was established to identify the components of each drug category using UV spectra obtained from TLC analysis. LC/MS and GC/MS were used to determine the optimal detection concentration of each drug by mixing the three placebo foods with drugs in 3 categories respectively. This paper shows the capability of the analytical method tested on the simulated food samples. Results showed that the optimal detection concentration of the three drug categories obtained are as follows: the concentration range of 7 ingredients of glucocorticoidsis from 1.25 mg/g prednisolone to 2.5 mg/g triamcinolone; 6 ingredients of anorexics is from 1.25 mg/g diethylpropion to 2.5 mg/g phentermine, 12 drugs of the third category is from 0.1 mg/g methaqualone to 3 barbitals (0.4 mg/g). The Standard Operating Procedures (SOPs) for the screening method, the UV spectra and the concentration of each drug offered as references for the qualitative method for the analysis