How High-Intensity Focused Ultrasound Works ? High-Intensity Focused Ultrasound (HIFU) is a cosmetic treatment for skin tightening that has been described as a non-invasive and painless replacement for face lifts. It requires no local anaesthetic and does not involve any cutting or injecting into the skin. There is no downtime required after treatment as seen in traditional surgical facelifts. HIFU therapy uses ultrasound energy to encourage the production of collagen, which results in firmer skin. HIFU uses focused ultrasound energy to target the layers of skin just below the surface. It can penetrate both the dermis and the superficial muscular aponeurotic system. These are the same layers that are tightened during conventional facelift surgery. The ultrasound energy causes the tissue to increase in temperature. Once the cells in the targeted area reach a certain temperature it stimulates the cells to produce more collagen ¡ª a protein that provides structure to the skin.