Karl, the main risk you run with a vasodilator treatment is that you will get a systemic effect in order to get the local effect. It may pay to get a blood pressure monitor if you don't already have one if you go down this path. They come cheap from any discount chemist warehouse and the accuracy is pretty good if you use it right. Alternatively just get familiar with your radial pulse. If its weak your BP is probably low, if not, plow on.