Hi,
As the fat cells are destroyed by cryolipolysis (e.g coolsculpting), some overlying skin laxity/wrinkling may become apparent.
Usually as the skin changes itself over time to adjust to the reduced underlying fat cells, the skin laxity/wrinkling will improve and disappear.
In the event that it persists after 9-12 months and if you wish for additional improvement, unipolar RF e.g. Thermage, or high intensity focused ultrasound e.g. Ultherapy may help tighten the loose skin under the chin and improve the appearance further.
Hope this helps!
