A qualitative study examining the nurse–patient relationship has identified the contagion of physical distress or ‘compathy’ as a significant but otherwise neglected phenomenon. Compathy occurs when one person observes another person suffering a disease or injury and experiences in one's physical body a similar or related distress. Thus, compathy is the physical equivalent to empathy. Although the contagion of physiological (compathetic) responses has been previously documented (for example, as couvades or psychogenic epidemics of the workplace), it has not been theoretically explicated. Triggers for the compathetic response are identified and include observing the suffering, hearing, or reading—or even thinking about—descriptions of the symptoms. The relevance of the compathetic response in the caregiving relationship and the necessity of suppressing the response when inflicting pain as a part of providing therapy are described. The concept of compathy is analysed and defended.