SummaryDifferent topical local anaesthetics have varying effects on skin blood flow and vascular reactivity. We compared the vasoactive properties of Rapydan Ò , a new topical local anaesthetic, with those of Ametop TM and EMLA TM creams in 20 healthy volunteers. Blood flow and vascular reactivity in the forearm skin were assessed by laser Doppler flowmetry and the transient hyperaemic response ratio respectively, before and after the application of EMLA (for 60 min), Ametop (for 30 and 60 min) and Rapydan (for 30 min). Application of EMLA had no effect on skin blood flow (median (IQR The use of local anaesthesia may be beneficial due to a possible increase in local blood flow. The evidence for the effects of local anaesthetics on blood flow and vessel reactivity is incomplete and contradictory, and the effects seen may depend on the drug used and the vessels studied [1][2][3][4][5]. Tetracaine (Ametop TM , Smith & Nephew Healthcare Ltd, Hull, UK) and eutectic mixture of 2.5% lidocaine and 2.5% prilocaine (EMLA TM ; AstraZeneca Ltd, London, UK) are widely used topical agents that provide anaesthesia of the superficial and deep skin layers. A medicated plaster containing lidocaine and tetracaine (Rapydan Ò ; EUSA Pharma (Europe) Ltd, Oxford, UK) is now available that can produce topical anaesthesia of the skin within 30 min [6,7]. The plaster is oval in shape, measuring approximately 80 · 60 mm, with an adhesive edge (allowing the plaster to be applied topically to the skin) surrounding a central area containing the active drug ingredients. This central area also contains a heat releasing component that warms the skin up to a maximum temperature of 40°C (with a mean temperature of 26-34°C) [8,9], theoretically enhancing drug absorption. The effect of Rapydan drug constituents and the heated plaster on the vascular reactivity of skin has not been established.Vascular reactivity can be altered by a variety of disease states including hypertension [10], diabetes mellitus [11] and sepsis [12]. Alterations in skin vascular reactivity may help predict responses in other more clinically significant vascular beds. Within the skin, vascular reactivity has been assessed using laser Doppler flowmetry and the hyperaemic response to a variety of stimuli including acetylcholine iontophoresis, heat and ischaemia. The transient hyperaemic response to 20 s of arterial occlusion allows an easily repeatable, non-invasive assessment of vascular reactivity to be made [13,14].Our primary hypothesis was that the application of a Rapydan plaster for 30 min would cause a greater increase in blood flow flux and a greater reduction in hyperaemic response than the application of Ametop for 60 min, by an alteration in vascular tone. The application of EMLA cream for 60 min has been shown to have no