Lidocaine, does it lessen the effects?

This is not a question that can be answered with one answer.  It depends on how much local anesthetic is used and if the tissues are very swollen during the treatment vs. a small amount of anesthetic that doesn't change the thickness (temporarily) of the skin and soft tissues. On the other hand, making the area numb and allowing the patient to have a more thorough treatment can create a better result.  If the tissues are temporarily more swollen from the anesthetic (if local injections in the treated area are done compared with regional blocks done away from the exact site) the doctor may be able to provide treatment with all transducers including the 4.5mm deepest.  I have been able to accomplish this on the forehead and have had some excellent results of forehead lifting, whereas, without the local anesthetic filling out the forehead, the 4.5mm transducer is too deep as the forehead bone is closer to the skin's surface compared to the cheek and its underlying structures. This is an off-label use of the device and your physician should discuss it with you thoroughly. Also this changes a procedure that is thought not to have down time with a treatment that can have bruising and swelling afterwards from the injections.

Lidocaine injections should not affect the results of the Ultherapy treatment, especially in the small doses given.

If lidocaine is used as a block, it's far enough from the treatment surface that it should not practically or theoretically affect results of Ultherapy.