thickened fluids are commonly advised to minimise the risk of aspiration in people with dysphagia, although many do not comply with this treatment. In health economics, utilities are values that reflect an individual's preferences for different health states. We examined the healthcare utilities, elicited using a time trade-off approach (TTO), from healthcare professionals and non-dysphagic patients, associated with long-term use of thickened fluids. the risk of aspiration with thin fluids was explained to consecutive hospital patients without dysphagia (n = 76) and to a convenience sample of healthcare professionals (n = 75) who were then randomly allocated to drink as much as possible of 200 ml of pre-prepared water of Grade 1 (very mildly thick) or Grade 2 (mildly thick) consistency. A standardised script with a ping-pong approach was then used to elicit TTO utilities for use of thickened fluids using a 10-year horizon. median (inter-quartile range) utilities were 0.7 (0.5-0.9) for those receiving Grade 1 and 0.5 (0.3-0.7) for those receiving Grade 2 consistency fluid (Mann-Whitney test, P = 0.001). Thus, for example, on average those allocated to Grade 2 fluid would be willing to sacrifice 5 years of a 10-year lifespan not to be restricted to fluid of that consistency. There were no significant differences between patient and professional values. patients and professionals judge that long-term use of thickened fluids would significantly impair quality of life. Utilities associated with more viscous fluids are particularly low.