[The alarm sounds, but there is no fire].

Many physical complaints cannot be explained by tissue damage or disease. The predictive-coding model describes the brain as an active predictive system that interprets signals based on expectations and actual input. Complaints arise from a dynamic interplay between predictions and signals, influenced by emotions, trauma, culture, and context. Strong expectations of symptoms can override actual signals, causing complaints to often persist after recovery. This explains also interindividual differences, discrepancies with objective findings, and the effect of psychological interventions. The model integrates biology, psychology, and context, and provides physicians with a framework to normalize complaints, and emphasizes diagnostics and integrated treatment.