Background: Drug reaction with eosinophilia and systemic symptoms (DRESS) is a delayed idiosyncratic severe cutaneous adverse reaction (SCAR) which may be potentially life threatening. Recently a simple scoring system for early screening of DRESS patients was derived combining hsCRP levels, eosinophil count and total body surface area (TBSA) (henceforth called CET score). The objectives of this study were validation, lead time advantage and cost-benefits of CET score compared to RegiSCAR scoring as gold standard. Methods: Prospective observational case control study, wherein 110 consecutive patients diagnosed with drug induced maculopapular exanthema during 18 months of study period were recruited. Patients were classified as cases (DRESS) and controls (maculopapular exanthema) (MPE) using RegiSCAR score cut off 2 (possible DRESS). They were also simultaneously screened using CET score based on which patients were classified as positive or negative. They were subsequently followed up on day 7 for a second comparison and assessment of lead time and at three and six weeks for assessment of clinical response. Results: Seventy cases and 40 controls were recruited. At a cut-off of >2.12, the CET score had a sensitivity of 94.29%, specificity was 60%, positive predictive value (PPV) of 80.5%, and a negative predictive value (PPV) of 85.7%. The median delay in diagnosing DRESS using RegiSCAR was around 12 hours. There was a median cost benefit of 12.13 $ in favor of CET score. Conclusions: CET score had good diagnostic performance in screening DRESS patients with lead time of 12 hours and fewer costs incurred.