The invention provides a device for application to the skin of a patient to facilitate intravenous access, e.g. via needles, syringes, cannulas or catheters, the device having an upper surface and a lower surface, wherein the lower surface is suitable for contacting the skin of the patient at the location of a vein to be accessed. The device comprises a heat patch, an organic nitrate vasodilator agent and an amino based anaesthetic agent which is an amino ester or amino amide. The device is configured and arranged such that in use the device can be activated by the application of pressure to the patch so as to initiate an exothermic chemical reaction in the heat patch which heats the patch to a temperature of from 50 to 55 degrees Celsius for a period of time of one minute or more. Further, the device is configured and arranged such that when the device is applied to the skin of the patient, with the lower surface contacting the skin of the patient, the vasodilator agent and the anaesthetic agent are released from the lower side of the device onto the patients skin at the location of a vein to be accessed.
