Cognitive behavioural models of hypochondriasis assume that dysfunctional illness-related beliefs are involved in the genesis and maintenance of the disorder. The role that other more general dysfunctional beliefs about thoughts play in this disorder has also been highlighted. Internal triggers such as illness-related intrusive thoughts could activate these beliefs.

The present paper examines whether general dysfunctional beliefs about distressing thoughts, such as intolerance of uncertainty, over-estimation of threat, and thought-action fusion-likelihood, mediate between illness-related intrusive thoughts and health anxiety symptoms.

A group of participants composed of individuals with hypochondriasis (n = 31; 51.5% women; mean age = 32.74 years, SD = 9.96) and community individuals (n = 219; 54.3% women; mean age = 39.56 years, SD = 15.20) completed a series of questionnaires to assess illness-related intrusive thoughts (INPIE), dysfunctional beliefs about thoughts (OBSI-R), and health anxiety symptoms (SHAI).

Results from a multiple parallel mediation analysis indicate that over-estimation of threat partially mediated the relationship between illness-related intrusive thoughts and health anxiety symptoms.

The results support the importance of the tendency to over-estimate the threat in the relationship between intrusive thoughts related to illness contents and health anxiety. Conceptual and clinical implications of these results are discussed.