Sagging or loss of firmness: is Density or XERF the better fit?
“My face has dropped” and “my skin has lost its firmness” are used almost interchangeably in the consulting room, but they often involve different layers. This column sorts Density and XERF by concern: when each is a candidate, and when it drops out.
The short answer
For sagging and for firmness alike, there is no comparative evidence that Density or XERF is the better fit. The two are both RF lifting devices and target overlapping layers — they heat the dermis and the structures beneath it, and a jawline that has started to drop is their main indication. So what needs sorting first is the concern, not the device. For sagging of the facial contour, both Density and XERF are candidates, and skin thickness, depth of sagging, area and attitude to anaesthesia decide which comes first. For thin skin that looks slack, the problem is often dermal material, so skin boosters may come first. For hollow cheeks, neither device is the answer. The guidance below is Miso Clinic’s clinical judgement, not something established by studies.
First, sort the concern: sagging, firmness or volume?
In the consulting room “no firmness” usually means one of three things: skin that springs back weakly when pressed, a facial contour that has dropped, or skin that looks thin and limp. Spring-back and a thin look are dermal problems; a dropped contour involves the fat and fascia beneath the dermis. Add deep fat loss that no longer supports the tissue above, and all of them read as “sagging” from the outside.
| What you see | Mainly which layer | Density / XERF | Treatment that fits |
|---|---|---|---|
| Lower cheeks dropping, jawline blurring, shadow beside the nasolabial fold | Beneath the dermis (superficial fat, fascia) | Candidate | RF lifting |
| Fine lines, pores, make-up not sitting well, thin dull skin | Dermal collagen and material | Limited | Skin boosters (Rejuran, GOURI, Rituo and others) |
| Hollow cheeks or temples | Deep fat, volume | Not a candidate | Fillers |
| Severe sagging with folding skin | Beyond non-invasive treatment | Not a candidate | Surgical consultation |
Layer thickness also varies widely. In 30 Korean and Thai cadavers measured with a 3D scanner, facial skin was 2.1 ± 0.4 mm and superficial fat 5.2 ± 1.9 mm — the standard deviation of the fat is 36% of its mean. In ultrasound records of 200 lower-face patients, sagging submental areas had thinner skin and thicker superficial fat. The same “sagging” puts the target layer in a different place from one person to the next.
If facial sagging is the concern, is Density or XERF more suitable?
For a facial contour that has started to sag, both Density and XERF are candidates. No human study has compared them for sagging, so Miso Clinic decides which to consider first from four conditions.
1. Skin thickness and depth of sagging
With thicker skin and deeper sagging we tend to consider Density first, because Density is designed to reach deep layers with monopolar and then shallow layers with bipolar in a single pulse. This follows from design; no study shows Density does better in thick skin.
2. How finely the face needs to be divided
Where narrow areas such as around the eyes and mouth need different settings from broad areas such as cheeks and jawline, we tend to consider XERF first: it switches between tips of different sizes by area and chooses between two frequencies. Density also has an Eye tip, so this alone does not decide it. For reference, in a split-face randomised trial that varied only electrode size (31 subjects), a 3 cm² tip did significantly better around the eyes — evidence that tip size and area may matter more than the device name.
3. Anaesthesia and pain tolerance
XERF is usually done without anaesthesia, and three XERF studies without anaesthesia reported mean pain of about 4 to 5 out of 10. Density uses numbing cream depending on area and settings, and the Density study (16 subjects) reported a mean of 1.4 on a 5-point scale. The scales and conditions differ and cannot be compared, so if one device was hard going before, trying the other is the practical rule.
4. How severe the sagging is
Density and XERF are both non-invasive RF. Sagging severe enough that the skin folds is beyond either device, and when that is the case we say so.
Improvement in sagging is judged two to three months later, not the next day. The longest published follow-up is 24 weeks for Density and 90 days for XERF, and none of the four studies has a control group.
If skin firmness is the concern, which treatment fits better?
The answer depends on what “firmness” means. If the skin looks slack because the contour has dropped, it is the sagging problem above and Density or XERF is a candidate. If the skin itself is thin and dull, what it needs first may be a skin booster that works on dermal material and environment, not heat.
Loss of firmness from sagging — Density or XERF
This is firmness lost as the jawline blurs and the lower cheeks drop. Density and XERF both rely on collagen contracting in response to heat and then remodelling. The choice between the two follows the four conditions in the previous section.
Loss of firmness from thinning skin — boosters first
If fine lines, pores and make-up that no longer sits well are the main concern and the skin feels thinner, Miso Clinic considers skin boosters before Density or XERF. RF does heat the dermis, but adding material to a thinned dermis or improving its repair environment is the territory of injectables.
Sagging and thinning together — split the sequence
More often the two come together. Then how RF and boosters are sequenced matters more than which RF device is chosen. One study gave intradermal cross-linked hyaluronic acid and added an energy device a month later according to concern (18 subjects, no control group), but it did not compare the combination with either alone. Order and intervals are covered in Can Density and a skin booster be combined? and Can XERF and Rejuran be combined?
A figure like “firmness improved by x%” means different things depending on which measurement (R2, R5, R7 and so on) was taken and how. None of the human studies of Density or XERF shows improved firmness against a control group.
When neither Density nor XERF comes first
In these situations Miso Clinic does not recommend Density or XERF first, or avoids the area, or changes the settings.
- Hollow cheeks or temples — tightening with heat can make hollows look deeper.
- Thin, dull skin as the main concern — a problem of dermal material, so boosters come first.
- Severe sagging with folding skin — beyond the range of non-invasive RF.
- Pigmentation or redness — not what RF treats.
- Pacemakers and other implanted electronic devices — Density and XERF both use monopolar RF, which passes current through the body.
- Metal implants or non-dissolvable filler in the treatment area — the area is avoided or settings adjusted.
Choosing by concern, on one page
| Concern | Considered first | Why |
|---|---|---|
| Blurred jawline, drooping cheeks, thicker skin and deeper sagging | Density | Sequential delivery design — no comparative data |
| Blurred jawline, drooping cheeks, no anaesthesia, same-day return | XERF | Usually no anaesthesia |
| Sagging in narrow areas around the eyes or mouth | XERF small tip / Density Eye tip | Tip size matched to area |
| Thin, dull skin without sagging (loss of firmness) | Boosters such as Rejuran, GOURI, Rituo | A dermal material problem |
| Sagging and thinning together | RF plus boosters in sequence | Different layers |
| Hollow cheeks or temples | Fillers | Not an RF indication |
| Severe sagging | Surgical consultation | Beyond non-invasive treatment |
Which treatment is best is decided by the state of your skin now, not by the product. In consultation we look first at what has been lost and what remains, before any product name. The design, results and pain of the two devices are compared in Density vs XERF in Daegu: which is better?
Frequently asked questions
For facial sagging, is Density or XERF better?
No human study has compared the two for sagging. Both are candidates for a contour that has started to drop, and Miso Clinic decides which comes first from skin thickness, depth of sagging, area and attitude to anaesthesia. We tend to consider Density first for thicker skin and deeper sagging, and XERF first when avoiding anaesthesia and treating area by area matters more; that is clinical judgement.
My skin has only lost firmness. Can I have Density or XERF?
First we look at what “firmness” means for you. If the skin looks slack because the contour has dropped, Density or XERF is a candidate. If thin, dull skin without sagging is the main concern, it is often a problem of dermal material, and Miso Clinic considers skin boosters first.
My cheeks are hollow. Can Density or XERF lift them?
Lost volume is not refilled by heat. Density and XERF tighten tissue, so in hollow cheeks or temples they can make the hollows look deeper. Volume loss is a filler question first.
When is improvement in sagging judged?
The tightness right after treatment is immediate collagen contraction and settles quickly. The lasting change is remodelling over weeks to months, so with either device results are judged two to three months later. In one RF study of 20 subjects, clinician assessment was not significant at four weeks and was significant at 12 weeks.
If I have sagging and loss of firmness, do I need both treatments?
When sagging and thinning come together, RF and boosters are often planned in sequence. We could not find a controlled study showing the combination beats either alone. There is no need to do everything at once; we start from whichever problem stands out most.
I am in my thirties. Do I need lifting for sagging?
It depends on the skin, not the age. In your thirties Density or XERF can be a candidate if the jawline is starting to blur; in your fifties RF is not first if the main problem is volume loss or thinning skin.
Can Density or XERF improve severe sagging?
Both are non-invasive RF. Sagging severe enough that the skin folds is beyond Density and beyond XERF, and in that case we say a surgical consultation is needed.
Read next
- Density vs XERF in Daegu: which is better? Results, differences and who each suits
- Choosing between Density and XERF in Daegu: what to check
- Facial sagging in Daegu — starting with which layer the treatment works on
- Choosing a skin firmness treatment in Daegu
- Lifting should change with skin thickness and fat volume
- Can Density and a skin booster be combined?
Product pages
The devices themselves are set out here. Density: monopolar and bipolar RF in turn · XERF: monopolar radiofrequency lifting
Who wrote this
Written and reviewed by Lee Chi-Hak, MD, medical director of Miso Clinic in Daegu, South Korea. Every study cited above is given together with its design, its size and the limitations the authors themselves recorded, and where we could not find data, we have said that we could not find any.
| Medical director | Lee Chi-Hak, MD |
|---|---|
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References
- Variation in facial layer thickness — Lee KW, Yoon JH, Kim JS, Hu KS, Kim HJ, Clinical Anatomy 2021;34(7):1050–1058, PMID 33583088, DOI 10.1002/ca.23726. 30 embalmed Korean and Thai cadavers, 3D scanner. Skin 2.1 ± 0.4 mm, superficial fat 5.2 ± 1.9 mm. Embalmed tissue may differ from living tissue.
- Lower-face layers on ultrasound — Kwon SH et al., Dermatologic Surgery 2022;48(5):527–531, PMID 35093961, DOI 10.1097/DSS.0000000000003393. Retrospective review of 200 patients. Sagging submental areas had thinner skin and thicker superficial fat.
- Electrode size, split-face trial — Yang YS et al., J Clin Aesthet Dermatol 2024. 31 subjects; around the eyes a 3 cm² tip did significantly better (p < 0.001). Not a comparison of Density and XERF.
- Density (sequential monopolar–bipolar RF) — Oku K, J Cosmet Dermatol 2025;24(10):e70504, PMID 41090512, DOI 10.1111/jocd.70504. Single clinic in Japan, single author; 16 adults aged 36–59, Fitzpatrick II–IV; one session; 24 weeks. Skin tightening distance on 3D imaging 0.82 ± 0.36 mm, lower-face tissue thickness reduction 0.89 ± 0.40 mm, 15 of 16 improved on GAIS, procedural pain 1.4 ± 0.6 on a 5-point scale, no severe adverse events. No control group. The abstract names the technology (sequential monopolar and bipolar pulsed RF) rather than the device.
- XERF — 20 subjects, Korea — Hwang JK, Medical Lasers 2025;14(1):23–30, DOI 10.25289/ML.24.035. Single centre; 20 subjects aged 28–63, Fitzpatrick III–IV; one session; 12 weeks. Blinded raters picked the post-treatment photo correctly 80% of the time, GAIS 2.75/4, satisfaction 7.84/10, pain without anaesthesia VAS 4 in nine and 5 in eleven, no adverse events. No control group. The journal is indexed in KCI and KoreaMed, not PubMed/MEDLINE or SCIE.
- XERF — 39 subjects, United States — Weiss RA, Wang J, DiBernardo B, Bhatia AC, Cureus 2026;18(3):e104546, PMID 41930066, DOI 10.7759/cureus.104546. Four sites; 39 subjects (mean age 54.4); two sessions four weeks apart; 90 days. GAIS of 3 or more as rated by the treating investigator: 84.6% at 30 days, 92.3% (36/39) at 90 days; mean pain without anaesthesia 4.2/10; mean 568.8 shots per session with one large tip. No control group, unblinded, device and study support from the manufacturer.
- XERF — 16 subjects, retrospective — Erlich G, Dahan E, Wolf Y, Lasers Med Sci 2026;41(1), PMID 42611100, DOI 10.1007/s10103-026-04996-0. 16 women; one session; three months; 600 shots split across three tip sizes. Pain without anaesthesia 4.31 ± 1.71 (3 or less 38%, 4–6 50%, 7 or more 12%); brow and eyelid 3D measurements +1.11 to 1.44 mm (the right lateral canthus value was not significant). Retrospective, no control group; the authors state no conclusion can be drawn on superiority over single-frequency devices.
- When RF results are judged — Shin J et al., Cosmetics 2024;11(3):71, DOI 10.3390/cosmetics11030071. Oligio device; 20 Korean women; rater-blinded single arm. Clinician assessment was not significant at four weeks and significant at 12 and 24 weeks. No control group, and not a Density or XERF study.
- Filler followed by an energy device — Oku M, Oku K, J Cosmet Dermatol 2025;24(10):e70485, PMID 41065147, DOI 10.1111/jocd.70485. 18 subjects, rater-blinded, no control group. Intradermal cross-linked hyaluronic acid, then one month later an energy device chosen by concern (including sequential monopolar–bipolar RF), assessed eight weeks later. Combination was not compared with either treatment alone.
- No device-to-device evidence — systematic review, Aesthetic Surgery Journal Open Forum 2026 (2015–2025; 15 studies, 1,230 subjects; one randomised controlled trial). No meta-analysis because of heterogeneity; no direct comparisons between devices were identified.
- Korean medical advertising law — Medical Service Act, Article 56(2), prohibits advertising through patient testimonials, comparison with other clinics and superlatives. That is why this column carries no “best” claims, no clinic comparisons and no prices.
Everything in this column is general information and does not replace medical diagnosis or treatment. Effects and side effects vary with individual skin condition, age and underlying illness, and the same result is not guaranteed for everyone. Any decision to proceed should be made in an in-person consultation with a physician.
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