Drug allergies pose a great deal of danger for the patients. It hinders effective treatment procedures in hospitalized patients. Moreover, it complicates the symptoms due to the allergic reactions of the immune system. Allergic reactions may arise against any medication including antibiotics and chemotherapeutics. Therefore, it is crucial to assess the sensitization pattern of the patients to culprit drug(s) before retreatment with the same or similar drug, or in order to confirm/exclude a suspected drug hypersensitivity reaction. In vivo and in vitro tests are performed in the evaluation of patients. Current methods of in vitro drug allergy evaluations rely on time consuming and expensive methods. Ficoll separation of peripheral blood mononuclear cells, their activation with stimulants in the presence of the drug of interest, CD69 or CD25 or BrdU or radioactive thymidine analysis of the cells after a couple of days of incubation is an excessively elaborate work and also uneconomical. Moreover, it requires a great deal of expertise to interpret the results. Here, we are reporting a new whole blood based lymphocyte transformation test method that does not require ficoll separation, CD69, CD25, BrdU and radioactive thymidine analysis. Thanks to the color change in the whole blood itself one can easily determine the allergic reaction to a certain drug. This new method is less time consuming, more economical and easy to apply.Copyright © 2020. Published by Elsevier B.V.