Information allergy is defined as (1) refusing to obtain key information needed to make a sound decision, or (2) ignoring important available information. The latter problem is epidemic in biomedical and epidemiologic research and in clinical practice. Examples include

• ignoring some of the information in confounding variables that would explain away the effect of characteristics such as dietary habits
• ignoring probabilities and “gray zones” in genomics and proteomics research, making arbitrary classifications of patients in such a way that leads to poor validation of gene and protein patterns
• failure to grasp probabilitistic diagnosis and patient-specific costs of incorrect decisions, thus making arbitrary diagnoses and placing the analyst in the role of the bedside decision maker
• classifying patient risk factors and biomarkers into arbitrary “high/low” groups, ignoring the full spectrum of values
• touting the prognostic value of a new biomarker, ignoring basic clinical information that may be even more predictive
• using weak and somewhat arbitrary clinical staging systems resulting from a fear of continuous measurements
• ignoring patient spectrum in estimating the benefit of a treatment

Examples of such problems will be discussed, concluding with an examination of how information–phobic cardiac arrhythmia research contributed to the deaths of thousands of patients.