The cost effectiveness of generic drugs has promoted their use worldwide. However, the large variety of bioequivalent generic and brand-name drugs found in the marketplace increases the complexity and frequency of mistakes in drug consumption. This clinical study investigated the prevalence of various mistakes in drug consumption by patients using a hospital setting. This prospective clinical trial used a hospital setting to identify errors in drug consumption. Six hundred patients who were hospitalized for a minimum of 48 hours in the Internal Medicine Departments were checked at various time points. The medications prescribed by their physician was determined and compared to the medications each patient carried on their person for de facto consumption. Drug consumption errors were found in 13 cases (2.17%), most of which involved duplicate drugs. In 6 of these (46.1%), patients consumed different drugs from the same therapeutic family. In 5 cases (38.5%), patients used chemically similar medications with different names, and in 2 cases (15.4%), patients consumed different drugs from various therapeutic families to treat the same medical condition. Ten of the thirteen cases (76.9%) had the potential to cause serious adverse drug events. More errors were found in female patients (53.8%), elderly patients, and those consuming a large variety of drugs. Variations in names, colors, shapes, and sizes of various drugs cause confusion and errors in drug consumption among patients. Some of these errors have the potential to cause severe, adverse drug effects and can increase morbidity and mortality worldwide.