Welting of the skin is unusual but a short limited side effect of Ultherapy. It is related to not keeping the transducer completely perpendicular to the skin during treatment (lines). Topical 1% hydrocortisone cream will help accelerate the resolution of these welts. read the Ultherapy...
RF devices use radiofrequency energy and can/will interfere with pacemaker and defibrillator activity. Ultherapy is safe with pacemakers and defibrillators. Lasers are safe with pacemaker and defibrillators.
I agree with Dr. Baxter and Dr. Shelton. Numbing cream will not interfere with Utherapy, but unfortunately, it will also not be helpful as the pain from the procedure is deeper then numbing cream penetrates. I find that patients tolerate the procedure very well with a combination of...