What Is HIFU? Does It Really Lift and Firm, and How to Care for Skin

HIFU (High-Intensity Focused Ultrasound) is a skin-lifting procedure using focused high-energy ultrasound that delivers energy deep into the skin down to the SMAS layer without surgery, stimulating collagen production to help skin look firmer and smoother. Results vary by individual. This article was reviewed by the Onnyx Clinic medical team.

In English the term may appear as both “HIFU” and “Hifu,” which refer to the same procedure.

What Is HIFU?

HIFU stands for High-Intensity Focused Ultrasound. It is a non-surgical, incision-free procedure for lifting and firming the face and neck, working by concentrating high-frequency sound-wave energy at a defined focal depth beneath the skin.

The core idea is to create small “thermal coagulation points” in the deeper layers of the skin without damaging the surface layer. When the body responds to these thermal points, a repair process and the production of new collagen (neocollagenesis) take place. Collagen is the protein that helps skin stay elastic and firm.

A key feature of HIFU compared with other energy-based lifting procedures is its ability to “aim” energy so it concentrates at a specific depth, bypassing the upper skin layer. This allows deeper tissue layers to be treated without necessarily damaging the outer skin, so it is typically an incision-free procedure with a relatively short recovery period.

The market has many HIFU models and brands. One common group is microfocused ultrasound technology, such as Ultraformer (made by Classys, South Korea); some models use technology that combines multiple energy-delivery modes to work faster and more comfortably. Each device differs in its features, indications, and standards certification: some models are approved in certain countries while still under study in others. Consumers should therefore ask the clinic for details about the specific device model before deciding.

How HIFU Works (Ultrasound to the SMAS Layer)

The heart of HIFU lies in delivering energy down to the “SMAS layer” (Superficial Muscular Aponeurotic System), a layer of fibrous tissue deep beneath the skin and the same layer surgeons address in a surgical facelift. The fact that HIFU can reach this layer without surgery is the reason the procedure draws interest.

HIFU devices can generally deliver energy at several depths. The most common are:

• 1.5 mm — the upper skin layer (epidermis/superficial dermis), focusing on skin smoothness
• 3.0 mm — the deep dermis
• 4.5 mm — the SMAS layer, focusing on lifting

When ultrasound concentrates at these depths, localized heat is generated in the range of about 60-70°C, causing tissue to contract immediately to a degree and triggering a repair process that leads to new collagen production over the following months. Results are therefore gradual rather than an immediate change.

Doctors often select cartridges of different depths for different areas of the face so that energy reaches the layer intended for treatment, for example using a 4.5 mm cartridge on the jawline and under-chin areas where lifting is emphasized, and shallower cartridges on areas of thin skin. Choosing the depth and position is therefore a skill that relies on understanding facial anatomy, because some positions, such as nerve pathways and certain muscle bundles, must be avoided for safety.

A systematic review of research found that HIFU produces significant skin-tightening results, particularly in the lower face, neck, and around the eyes, with reported reductions in skin laxity in the range of about 18-30% in the reviewed studies. These figures come from the studies, and results may vary by individual.

Which Areas Can HIFU Lift and Firm?

HIFU is often used to treat areas of the face and neck that are beginning to show mild to moderate laxity. Popular treatment areas include the jawline, jowls, under-chin, neck, and brow area. Some positions, such as around the eyes and the temples, are areas requiring particular care on a case-by-case basis and should be treated by an experienced doctor.

The following table summarizes the areas HIFU can often treat, along with results that may be expected. Results vary by individual:

HIFU is not designed to replace a surgical facelift. In cases of significant skin laxity, the doctor may recommend other options that are more suitable.

Who Is HIFU Suitable For?

HIFU may suit people who:

• Are beginning to show mild to moderate skin laxity in the jawline, jowls, or neck
• Want to maintain skin firmness without surgery and prefer to avoid a long recovery period
• Have overall healthy skin with no wounds or infections in the area to be treated
• Understand that results are gradual and vary by individual

However, there are groups who should avoid it or always inform the doctor first, including: people who are pregnant; people with an infection or open wound in the area to be treated; people with implanted electronic devices in the body or metal implants in the position to be treated; people with severe inflammatory acne; as well as people with certain underlying conditions that affect wound healing, such as poorly controlled diabetes or a weakened immune system. Assessment by an experienced doctor before treatment is therefore very important.

Does HIFU Hurt?

During HIFU, many people feel warmth, a tingling sensation, or a deep, rhythmic prickling at the points where energy is delivered, especially in areas where the skin is thin or close to bone. The level of sensation differs from person to person and from area to area.

HIFU generally does not require general anesthesia. The doctor may adjust the energy level appropriately for greater comfort, and in some cases may consider a topical anesthetic or pain reliever as appropriate.

After treatment, the skin may be red, slightly swollen, feel tight or tender to the touch, or show slight bruising in some people, which usually improves gradually within a few days to about a week. Less common side effects worth knowing about include temporary numbness or temporary abnormal facial muscle function in areas related to nerves, which in most reports tends to recover on its own within a few weeks. Having the treatment performed by an experienced doctor who understands which positions should be avoided therefore helps reduce these risks. If you have severe or prolonged abnormal symptoms, contact the clinic where you had the treatment immediately.

How Many HIFU Lines, When Do Results Show, and How Long Do They Last?

Number of shots: The “shots,” or number of lines/points of HIFU, has no fixed number; it depends on the treatment area, skin condition, and a treatment plan the doctor designs for each individual. A full-face and under-chin treatment may use a fairly large number of lines, so the doctor should assess first to determine a suitable amount. Delivering an excessive number of shots unnecessarily does not always improve results and adds risk.

When results show: Many people feel slightly firmer skin early on from tissue contraction, but clearer results usually appear gradually over 2-3 months as new collagen is built, and may continue to develop up to around 3-6 months.

How long they last: From a review of the academic literature, HIFU results often last in the range of about 12-24 months. One study reported that most participants experienced continued satisfaction with firmness and improved wrinkles for up to 1 year (the satisfaction proportion rose from about 42% at 90 days to about 53% at 360 days). Results depend on age, skin condition, and self-care. Collagen gradually declines naturally with age, so many people consider repeating treatment for ongoing maintenance roughly every 9-12 months.

How to Care for Skin Before and After HIFU

Before treatment:

• Inform the doctor of your health history, underlying conditions, medications used, and any implanted devices/metal in the body
• If you use retinoid- or steroid-class medications applied to the area to be treated, you may need to stop in advance per the doctor’s advice (often about 2 weeks is recommended)
• Avoid alcoholic beverages and get plenty of rest before the treatment day

After treatment:

• Avoid intense sunlight and apply sunscreen regularly, as the skin may be more sensitive to light
• Avoid very hot water, saunas, and strenuous exercise during the first 48-72 hours
• Avoid irritating products such as scrubs or exfoliating acids, and avoid facial massage or pressing the treated area for 2-4 weeks
• Choose gentle cleansers and moisturizers; if there is redness or swelling, a cold compress may help relieve it

If you have abnormal symptoms such as unusually severe pain, numbness, or abnormal facial muscle function, contact the clinic where you had the treatment immediately.

Genuine vs. Substandard Devices

Today there are many HIFU models on the market, both certified-standard and substandard. Choosing a suitable clinic and device is therefore important for both results and safety. You should consider:

• The device and transducer cartridge are genuine and have the relevant standards certification
• The procedure is performed by a doctor or trained personnel at a properly registered clinic
• Skin condition and contraindications are assessed before every treatment
• Cartridges and consumables are counted and not expired

Substandard devices or counterfeit cartridges may deliver energy unevenly, leading to results that do not match expectations and increasing the risk of side effects. If you are unsure, you can always ask the clinic about the device model and certification before deciding.

Summary

HIFU (High-Intensity Focused Ultrasound) is one option for maintaining the firmness of facial and neck skin without surgery, using high-energy ultrasound delivered down to the SMAS layer to stimulate collagen production. Results are gradual over 2-3 months and may last around 12-24 months, depending on the individual. What matters is having suitability and contraindications assessed by an experienced doctor, along with choosing a device and clinic that meet standards.

Read more about our HIFU lifting service.

If you would like to discuss whether HIFU is right for your skin, the Onnyx Clinic medical team is glad to provide individual advice. Prices are given as ranges; please ask for details and book a skin assessment via LINE @onnyxclinic.

References

• A Systematic Review of High-Intensity Focused Ultrasound in Skin Tightening and Body Contouring (Aesthetic Surgery Journal, 2025)
• A Systematic Review of the Efficacy of Microfocused Ultrasound for Facial Skin Tightening (PMC)
• Customized Treatment Using Microfocused Ultrasound with Visualization: Pan-Asian Gold Standard Consensus (JCAD)
• Complications and Risks of High-Intensity Focused Ultrasound (HIFU) in Esthetic Procedures: A Review (MDPI Applied Sciences)
• Ultraformer MPT — CLASSYS (Manufacturer)