A morbilliform drug eruption is the most common condition leading to a dermatology consultation for a patient in the hospital. Timing is an important diagnostic tool since the onset of a skin rash usually takes place within days-to-weeks of the start of the implicated drug. A comprehensive, thorough, and reliable drug history by the clinician is essential. Therefore, to assist in the task of determining the causative medication of a new skin rash in a hospitalized patient, the creation of a drug calendar is recommended. The development of an electronic version of the drug calendar offers several benefits over the manual version. As the use of electronic medical records continues to become the standard in medicine, the electronic drug calendar will serve as an invaluable tool for the diagnosis of drug hypersensitivity.