HIFU, or High-intensity focused ultrasound is a treatment that uses high intensity ultrasound waves to heat up the deeper layers of the skin below the surface. This stimulates new collagen production and helps in skin tightening and prevention of facial sagging.
HIFU is an effective treatment that can be performed after jaw botulinum toxin treatment, however, it may be preferable to do the procedure 1 to 2 week after the injection as you do not want the heat generated from the HIFU treatment to interfere with the botulinum toxin injected.