This paper makes an attempt to provide a thorough insight into the essence of causative-consecutive interaction and prove that it is the base of scientific knowledge. Everything in the world has its cause and effect. They are essential components of medical knowledge which are reflected in medical terms. The aim of the article is to investigate the way medical terms represent the gnoseological category of cause and effect, to reveal its explicit and implicit characteristics. The methods of definitional, derivational, semantic, categorical, conceptual, and compositional analysis are used in the investigation. The paper assumes the terms representing the category of cause and effect prevail in medical terminology. This prevalence is due to extralinguistic factors such as aetiology and the consequences of a disease. The authors introduce the notion “causal term relevance” and develop a number of rules of relevance. These rules and the study of extralinguistic factors and implicit logical links between word(term)-building elements revealed 11 prototype causative-consecutive characteristics. Each group represent one type of causative-consecutive relations. Definite category features, demonstrating cause and effect categories, combine terms in every group. Conclusion. The category of cause and effect is one of the most important medical concepts because it deals with the theory of pathology and is able to represent both the aetiology of the diseases and the conditions of the development of the disease by language means. The choice of language means by the author of the term influence the evolution of the scientific concept.