Research has suggested that a rigid dichotomy between small and professional talk is misleading given the porous nature of ‘types’ of talk. Yet, other research considers this distinction helpful in understanding the functions of talk in situated contexts. This article contributes to this discussion by discussing one type of small talk—co-topical small talk (CST). Drawing from Hudak and Maynard’s (2011) understanding of CST as talk that combines instrumental and small talk, we further discuss the bigness of such talk in holistic medical encounters. Specifically, we focus on the ambiguity embedded in participants’ turns that allows the navigation of topics between the small/big talk distinctions. We use Conversation Analysis focusing on a routine traditional Chinese medicine doctor–patient encounter. Our data present a case where CST comfortably and appropriately emerges and develops into extensive troubles talk that forms the main activity in caring for older adults. We conclude that the smallness/bigness of talk is determined by the nature of the context and the relevancy of the topic to the encounter