The viscosity of nonsolid foods and the stability of their viscosity over time is critical in managing dysphagia. The time-dependent viscosity of liquids thickened with starch-based thickeners was measured at constant temperature and shear rate. Viscosity was measured between 30-min intervals of rest (zero shear) over a period of 17 h at 20.0°C. Two common types of thickeners were evaluated: maize-based and maltodextrin-based (the latter commonly used in pediatrics). The maize-based thickeners undergo a significant decrease in viscosity over the initial 1–4 h following preparation. The maltodextrin-based thickener’s viscosity increases significantly 30 min following preparation and is then more stable over time than its maize-based equivalent. These findings suggest that the success of current dysphagia therapies that use thickeners could be influenced by the time-dependent nature of thickened fluid viscosity. Acknowledgment and appropriate selection of the thickener type is shown to be of great importance.