The research tradition on social relationships, social networks, and health dates back to the beginning of sociology. As exemplified in the classic work of Durkheim, Simmel, and Tönnies, social relationships and social networks play a double-edged-protective and detrimental-role for health. However, this double-edged role has been given unbalanced attention. In comparison to the salubrious role, the deleterious role has received less scrutiny and needs a focused review and conceptual integration. This article selectively reviews the post-2000 studies that demonstrate the harmful physical and mental health consequences of social relationships (intimate relationships and parenthood) and social networks. It uses a parsimonious three-category typology-structural forms, structural composition, and contents-to categorize relationship and network properties and proposes the social cost model, in contrast to the social resource model, to synthesize and integrate the adverse aspects of these properties. It concludes with future research directions.
Keywords: health; social cost; social network; social relationship; social resource.