Linear HIFU
Linear Z · Linearfirm · HIFU for fat and jawline
'Linear' HIFU is the current Korean export story in Thailand, Malaysia and Singapore, marketed for double chins and jawline fat rather than for lifting.
Mapping the fat before you heat it is the whole discipline; the line is only a shape.
Reviewed against the Aesthetics International standard. Category: Energy devices.
Does Linear HIFU work?
Promising. Mapping the fat before you heat it is the whole discipline; the line is only a shape. Thin.
- Verdict
- Promising Plausible mechanism and early evidence. Reasonable to try with realistic expectations.
- Evidence base
- 3 PubMed-indexed studies cited below, including systematic reviews, randomised trials.
- Suits
- A small, soft double chin in someone with good skin recoil who wants a non-injectable option, usually as part of a jawline plan rather than alone.
- Not for
- A heavy neck, loose skin that will hang once the fat shrinks, or a chin whose fullness is bone or muscle rather than fat. It does not replace liposuction or a neck lift.
- In Singapore
- Linear Z and similar devices are Korean medical devices used in some Singapore clinics; confirm the device's HSA registration with the provider.
- Category
- Energy devices
- Reviewed
- 1 October 2026 by Aesthetics International. Revised as evidence and regulation change.
What it is
A focused-ultrasound device whose transducer lays energy down in continuous lines rather than a row of dots. The linear mode heats a broader zone of superficial fat, which is why these devices are sold for the submental area, the lower cheeks and small body pockets; most also carry conventional dot cartridges for lifting.
How it works
Dot HIFU creates discrete coagulation points in the dermis and SMAS for contraction. Linear delivery heats a strip of tissue in the fat layer to the temperature at which fat cells are injured and slowly cleared. Depth selection decides whether you are tightening or de-bulking, and the two are often combined in one plan: lines through the fat under the chin, dots along the jawline for support.
What the evidence says
Thin. A 2026 prospective case series of 38 Korean adults using dual dot-and-linear HIFU reported measurable submental volume reduction and an improved cervicomental angle at 12 weeks, with mild transient effects, but it was a single-arm study with no control and no long-term follow-up. Older multicentre trials of body HIFU for abdominal fat reported circumference reduction, and a 2025 systematic review supports HIFU for both tightening and modest contouring. Nothing yet compares linear HIFU with deoxycholic acid, RF microneedling or liposuction for the chin.
What people are saying
Paraphrased from public discussion on TikTok, Instagram, Reddit and in the press. Not testimonials, and not about any one clinic. Reported in: rederm.co, herclinic.my.
What the studies show
- case series
A single-arm series of 38 adults reported zone-specific submental volume reduction and an improved cervicomental angle at 12 weeks after dot-and-linear HIFU, with mild transient adverse events.
Dual-approach High-intensity Focused Ultrasound for Facial Contour Modulation and Submental Reduction. — Plast Reconstr Surg Glob Open, 2026. PMID 42488921.
- RCT
Two multicentre studies found a mean waist circumference reduction of about two centimetres at 12 weeks after a single body HIFU treatment, regardless of fluence protocol.
High-intensity focused ultrasound for the reduction of subcutaneous adipose tissue using multiple treatment techniques. — Dermatol Surg, 2014. PMID 24852468.
- systematic review
HIFU produced modest circumference reduction in body contouring and consistent tightening, with standardisation of protocols identified as the main gap.
A Systematic Review of High-Intensity Focused Ultrasound in Skin Tightening and Body Contouring. — Aesthet Surg J, 2025. PMID 40184185.
Studies are selected for relevance and quality, not for agreement with the verdict; PubMed records are linked so the reader can check them.
Who it suits
Suits
A small, soft double chin in someone with good skin recoil who wants a non-injectable option, usually as part of a jawline plan rather than alone.
Not for
A heavy neck, loose skin that will hang once the fat shrinks, or a chin whose fullness is bone or muscle rather than fat. It does not replace liposuction or a neck lift.
Alternatives
The two reviewed treatments most often weighed against Linear HIFU, on the same standard.
| Linear HIFU | HIFU | Monopolar radiofrequency | |
|---|---|---|---|
| Verdict | Promising | Vetted | Vetted |
| What it is | A focused-ultrasound device whose transducer lays energy down in continuous lines rather than a row of dots. | High-intensity focused ultrasound delivers heat to precise points at set depths — commonly 1.5, 3.0 and 4.5 mm — creating coagulation points in the dermis and the SMAS layer that contract and stimulate collagen over months. | A single large electrode delivers radiofrequency energy that travels through the tissue to a grounding pad, heating the dermis and subcutaneous layer volumetrically. |
| Evidence base | 3 PubMed-indexed studies cited below, including systematic reviews, randomised trials. | 3 PubMed-indexed studies cited below, including systematic reviews. | 3 PubMed-indexed studies cited below, including systematic reviews. |
| Suits | A small, soft double chin in someone with good skin recoil who wants a non-injectable option, usually as part of a jawline plan rather than alone. | Mild to moderate laxity with reasonable skin thickness, people who want a structural effect without injectables. | Mild to moderate laxity of the face, eyelids, neck and body; people who prefer a no-needle, no-injectable approach. |
| In one line | Mapping the fat before you heat it is the whole discipline; the line is only a shape. | HIFU or radiofrequency is the wrong question — they do not do the same job, which is why 3D Facial Reconstruction uses both. | The device delivers heat; the protocol decides where it goes and in which order. That is the whole difference between tightening and lifting. |
Risks
Tenderness and swelling, occasional bruising, and uneven contour or a dent if lines are stacked too densely in one spot. Marginal mandibular nerve irritation is rare but real along the jaw.
In Singapore
Linear Z and similar devices are Korean medical devices used in some Singapore clinics; confirm the device's HSA registration with the provider. Energy at the depth of the fat layer should be delivered by a doctor who has mapped the plane, not by a technician following a shot count.
“Mapping the fat before you heat it is the whole discipline; the line is only a shape.”
Vetted protocols on the same problem
Questions
Does linear HIFU remove a double chin?
How is it different from normal HIFU?
How many sessions?
Cite this review
Aesthetics International (2026). Linear HIFU: does it work? Evidence, risks and verdict. https://aesthetics-international.org/treatments/linear-hifu/ (reviewed 1 October 2026).
Editorial, unpaid and independent of any manufacturer. Verdict: Promising. See what works and what doesn't across all 153 reviews. Spotted an error or a newer study? Suggest a correction — changes are logged on the corrections page. Terms are defined in the glossary.
Where this review is used
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