Anchoring bias is a type of heuristic that uses an initial source of information as an anchorfor basis of decision making. Then judgments and thought processes are led by this sole foundation. There are many different types of influences and bias used in medical decision making, which has prompted concerns regarding their impact on diagnostic inaccuracies. Studies have identified anchorconducted in medical literature, clinical vignettes and real life scenarios. These cognitive bias and aversions to ambiguities can lead to medical errors, inappropriate use of resources, and harm to the patient. We present a unique case of acute metabolic encephalopathy impacted by anchoring diagnosis of drug overdose that later confirmed a diagnosis of brain tumor.