A fat-dissolving injection in Korea is a series of small injections that break down fat cells in one spot, and large randomized trial data exist for just one product: deoxycholic acid for fat under the chin. Clinics often sell it beside two other things under the V-line injection label: botulinum toxin into the masseter, which slims a wide jaw by shrinking muscle, and house contour cocktails, whose blends have not been tested in comparable trials. Swelling under the chin usually lasts several days after each session. Treatments are spaced about a month apart, and most people need two or more. Flying home the same day is generally possible.
Guide
Three different things sold as a V-line injection
On Korean menus, V-line injection, contour injection and face slimming shot can name three unrelated treatments, so first ask which one the clinic means.
Deoxycholic acid is a fat-dissolving drug injected into a fat pad, most often under the chin. Botulinum toxin (Botox) goes into the masseter, the chewing muscle at the jaw angle, and works only on muscle. A contour cocktail is a clinic or distributor blend whose ingredients vary by menu.
| Option | What it targets | How it works | Evidence base | Typical visits |
|---|---|---|---|---|
| Deoxycholic acid injection | Fat pad under the chin | Destroys fat cell walls in the injected area | Phase 3 randomized trials | Up to six in the trial, about a month apart |
| Masseter toxin | Bulky chewing muscle | Relaxes the muscle so it slowly shrinks | Widely used, muscle effect only | One, repeated every few months |
| Contour cocktail | Cheeks and jawline, sold as slimming | Depends on the blend | No comparable trial data | Varies by clinic |
Guide
Fat or muscle: what is making the lower face look wide?
A soft fullness under the chin that you can pinch is fat. A square angle that hardens when you clench is muscle. Many faces have both, and the doctor should check each by touch.
The two do not overlap. Toxin will not touch a double chin, and a fat-dissolving drug will not slim a strong masseter. If loose skin or bone width is the cause, neither helps much.
Guide
What the deoxycholic acid trial actually showed
The REFINE-1 trial, published in Dermatologic Surgery in 2016, gave ATX-101 (deoxycholic acid) or a placebo to 506 adults with moderate or severe fat under the chin. Jones and colleagues found that 70.0% of treated people improved by at least one grade twelve weeks after the last session, against 18.6% on placebo, and their MRI scans showed a volume drop in 46.3% versus 5.3%.
The trial also shows the limits. Only 13.4% reached a two-grade improvement, and the study covered the area under the chin only, not the cheeks or jawline. Side effects in REFINE-1 were mostly mild, short-lived reactions at the injection site, though the trial recorded weakness of the nerve that moves the lower lip in 4.3% of treated people, which resolved without lasting effect.
Guide
Why a clinic contour injection is not the same evidence
A contour injection in Korea is often a house blend sold for the whole lower face. REFINE-1 tested one defined drug at a fixed dose in one area, so its results cannot be borrowed for a cocktail with a different recipe, dose or site. A clinic citing deoxycholic acid research for its own blend is stretching the data.
Ask for the product name, ingredient list and vials per session, and see the sealed packaging.
- Is this deoxycholic acid or a mixed blend?
- Which area will be injected, and how much product goes in each side?
- How many sessions are planned, and how far apart?
- What happens if the result is uneven or a hard lump forms?
Guide
How patients describe the experience afterward
A 2025 Aesthetic Surgery Journal study by Fijany and colleagues used language-analysis software on online reviews from 2014 to 2024. Of 585 reviews about deoxycholic acid injections, 55.2% were positive, against 83.4% of 753 reviews about suction under the chin, and injection reviews more often voiced sadness or fear.
Online reviews are weak evidence, but they show a trade-off: no incision, yet a gradual result that needs several visits.
Evidence
Research behind this page
- REFINE-1, a Multicenter, Randomized, Double-Blind, Placebo-Controlled, Phase 3 Trial With ATX-101, an Injectable Drug for Submental Fat ReductionDermatologic Surgery · 2016 · doi:10.1097/DSS.0000000000000578
In 506 adults, deoxycholic acid injections under the chin produced at least a one-grade improvement in 70.0% versus 18.6% with placebo, with mostly mild, transient side effects.
- Comparison of Patient Reviews for Submental Liposuction and Kybella Using Deep Learning and Natural Language Processing: Is There a Superior Intervention for Submental Adiposity?Aesthetic Surgery Journal · 2025 · doi:10.1093/asj/sjaf129
Analysis of 1,338 online reviews found 55.2% of deoxycholic acid reviews were positive compared with 83.4% of reviews for suction under the chin.
FAQ
Questions about Vline Nonsurg in Gangnam
How long does the swelling last after a double chin injection in Korea?
Swelling under the chin usually peaks over the first few days and settles within one to two weeks. Bruising, tenderness and a numb or firm feeling at the site are also common and short-lived. Because the area can look fuller before it looks slimmer, plan photos and events at least two weeks after a session, even though flying home the same day is generally possible.
How many fat-dissolving sessions are usually needed?
Most people need two to four sessions, spaced about a month apart, and some need more for a larger fat pad. In the REFINE-1 trial, 55% of treated people had improved by one grade after two treatments and 75% after four. A clinic should estimate the number of visits at the consultation so you can plan trips and costs around it.
Does face slimming in Korea with injections change the cheeks?
Injections rarely change the cheeks in a measurable way, and trial evidence for fat-dissolving drugs covers only the area under the chin. A wide face from the front is more often due to masseter muscle, bone or loose skin than to cheek fat. Ask the doctor to say which of these applies to you before agreeing to an injection marketed for cheek slimming.
Who should not have a fat-dissolving injection?
It is not suitable during pregnancy or breastfeeding, with an infection or inflamed skin in the area, or with a swelling under the chin whose cause is unclear, such as an enlarged gland. Loose skin with little fat is also a poor fit, because removing fat can make laxity more visible. Mention blood thinners and earlier neck surgery. A short consultation should rule these out first.
Can the fat come back after it is dissolved?
Fat cells destroyed by the drug do not grow back, but the remaining cells in the area can still enlarge if you gain weight. The REFINE-1 results were measured twelve weeks after the last treatment, so the trial says nothing on the very long term. Keeping a stable weight is the most practical way to hold the result, and a later top-up session is sometimes discussed.
Is it safe to combine jaw toxin and a chin fat injection on one trip?
Many doctors treat the masseter and the area under the chin in the same visit, because they are separate tissues and injection sites. The risks add up rather than cancel out: toxin can briefly tire chewing, while the fat injection brings swelling. Ask whether both are needed for your face. If you are unsure how you will react, the doctor can space them over two visits.