Medical diagnoses and prognoses are often not clear-cut ‘facts’. Conveying these kinds of vague phenomena is a challenge to health professionals, but also a skill that they must master. This study analyses real-life medical data to generate communicative patterns and verified strategies that shape the ways in which professionals communicate uncertainty. The findings may help healthcare professionals to deliver medical information in ways more accessible to the public. Elasticity plays an integral role in imparting medical advice to patients effectively and affirming their choices. This study is the first to explore communication effectiveness in healthcare, paying special attention to the role of elasticity in language use and in an Australia–Taiwan comparison. This research adds a new dimension to the study of health communication and explores better ways to deliver medical information to the public, by challenging linear theories in linguistics and promoting non-linear concepts. Language cannot be totally held to a ‘correct’ standard, nor used just as one wishes. A ‘one size fits all’ rule for language use does not exist, and instead multiple standards guide our use of it.