I do not believe Ultherapy will work for your legs. It is designed to cause controlled injury of the SMAS facia in the face to cause contraction of the SMAS which then lifts the soft tissue. It does not "tighten" skin like an ablative LASER treatment would. I would not expect much of a noticeable improvement in skin tightness of the legs with Ultherapy.
At our office we prescribe a medication for pain as well as something to relax you. Each office probably has a different protocol, so I'd ask the provider who is going to treat you what medications they are willing to prescribe to reduce any discomfort. Few people can tolerate the procedure without a prescription medication. The topical numbing agents can be helpful somewhat, but considering the depth that the treatment is delivered at, I'd recommend that you have prescription medication on hand in case you find it is more uncomfortable than you expected. Thank you for your question.
Ultherapy shouldn't hurt much after treatment. During treatment using injectable numbing helps limit pain much more. Best, Dr. Emer.
My office has found that in addition to topical numbing cream (which works better the longer you keep it on) that a combination of high dose ibuprofen and Xanax seems to work best. We do offer narcotic (Percocet or Norco), but it doesn't seem to take the edge off the way Xanax does.