The use of elastomeric diffusers (EDs) has grown together with the expansion of home care. In these devices, the fill volume of the drug reservoir and the flow rate are preset and cannot be modified. The elastomer, which makes up the reservoir walls, is what makes the infusate flow due to the pressure it exerts. The purpose of this work was to quantify, under standardized experimental conditions and following recommended conditions of use, the mechanical performances of the 2 commonly used elastomers (silicone and polyisoprene) and their impact on infusion flow rate consistency. Results show that they exhibit different mechanical performances which leads to concerns regarding the use of these devices for some intravenous (IV) therapies.