Skin & Aesthetics · Acne scars
TCA CROSS Treatment in Seoul for Ice Pick and Deep Scars
TCA CROSS (chemical reconstruction of skin scars) is a scar treatment in which a doctor presses a high concentration of trichloroacetic acid into the base of individual narrow, deep acne scars, triggering new collagen that gradually lifts each scar from below. At Hommage Clinic in Gangnam, Seoul, Dr. Hwang Seonhwa selects which scars suit TCA CROSS and plans it alongside resurfacing for the surrounding skin.
Quick answer
TCA CROSS(chemical reconstruction of skin scars) places high-strength trichloroacetic acid only inside narrow, deep acne scars so new collagen lifts them from the base. At Hommage Women's Clinic in Gangnam, Seoul, Dr. Hwang Seonhwa applies it scar by scar in a 15–30 minute session. Most people need 2–4 sessions about 4–8 weeks apart, with small crusts for 5–7 days. It works best on ice pick scars, improving rather than erasing them.
Key takeaways
- Best for ice pick scars, then narrow deep boxcar scars; not for rolling scars.
- Only the scar is treated, so recovery is short and most people work the next day.
- Higher acid strengths have not clearly beaten lower ones but cause more side effects.
- Temporary dark marks are the main risk in Asian skin; sun protection matters.
Infographic
TCA CROSS in numbers
Session time
Depends on how many scars are treated.
Acid strengths
Range used in published studies; chosen for your skin.
Sessions
Typical course, about 4–8 weeks apart.
Crusts
Small dark crusts fall off on their own.
Collagen build-up
After each session, the scar floor rises.
Studies reviewed
937 patients in a 2026 review of TCA CROSS.
TCA CROSS at a glance
| Key fact | Details |
|---|---|
| What it is | High-strength TCA, often 50% or stronger, applied only inside individual narrow, deep scars |
| Treatment time | Usually 15–30 minutes, depending on how many scars are treated |
| Comfort | Brief stinging or burning for seconds to minutes; numbing is rarely needed |
| Sessions | Typically 2–4 sessions about 4–8 weeks apart; deep scars sometimes need more |
| Downtime | Small dark crusts on treated scars for about 5–7 days; pinkness for several weeks |
| Results visible | Gradually over 2–3 months after each session as collagen fills the scar base |
| Performed by | Dr. Hwang Seonhwa or another Hommage Clinic physician |
TCA CROSS may suit you if you have
- Ice pick scars that look like deep, enlarged pores
- Narrow, deep boxcar scars with steep walls
- Deep scars that did not improve much with laser or microneedling alone
- Acne that has been under control for a few months
Wait or discuss another option if you have
- Active breakouts, cold sores or a skin infection in the area
- Pregnancy or breastfeeding (cosmetic scar treatment is usually postponed)
- A tendency to keloids or a history of poor wound healing
- Taken isotretinoin recently (timing is decided with your doctor)
What is TCA CROSS and how does it work?
TCA CROSS is a focused chemical treatment for narrow, deep acne scars. Instead of peeling the whole face, the doctor uses a fine, pointed applicator to place a small amount of high-strength trichloroacetic acid (TCA), often at 50% strength or more, only on the floor and walls of each scar.
The acid causes a controlled injury inside the scar, seen as a white “frost” within seconds. As that tissue heals over the following weeks, the skin lays down new collagen, which gradually raises the base of the scar and narrows its opening. Because the skin around each scar is left untouched, it heals quickly, and the risk of pigment change is lower than with a deep full-face peel. The technique was first described in the medical literature in 2002 and is now widely used for ice pick scars.
Which scars does TCA CROSS treat?
TCA CROSS works on scars that are narrow and deep. It is not designed for wide or shallow scars, which respond better to other methods.
- Ice pick scars: the main use. See ice pick scar treatment .
- Narrow, deep boxcar scars: often improve over several sessions; wide or shallow boxcar scars usually need resurfacing instead. See boxcar scar treatment .
- Rolling scars: not a good match, because they are pulled down by fibrous bands that need subcision . See rolling scar treatment .
- Raised scars and keloids: not treated with TCA CROSS.
Because most people have a mix of scar types, TCA CROSS is usually one part of a wider scar plan.
What happens during a TCA CROSS session?
A session usually takes about 15–30 minutes, depending on how many scars are treated, and you go home the same day.
- Your skin is cleansed and degreased so the acid acts evenly, and the scars to be treated are identified under good lighting.
- The doctor presses the acid into each scar with a fine applicator, one scar at a time, until a white frost appears.
- You feel stinging or burning for a few seconds to a few minutes per area, which a fan or cool compress eases. Numbing cream is rarely needed.
- A soothing ointment or moisturizer is applied, and you receive written aftercare instructions.
If you get cold sores, tell the doctor beforehand, as an antiviral medicine may be advised.
How long does TCA CROSS take to heal, and when will you see results?
Each treated scar forms a small dark crust that usually falls off by itself in about 5–7 days. The spot may then stay pink for several weeks before it settles.
Improvement is gradual. New collagen builds over about 2–3 months after each session, so a series of typically 2–4 sessions, about 4–8 weeks apart, is common, and deep scars sometimes need more. Treated scars become shallower and less noticeable in most people; they are improved rather than erased. To help the skin heal well:
- Do not pick or scrub the crusts; let them shed naturally.
- Cleanse gently and keep treated spots moisturized with the products you are given.
- Use a broad-spectrum SPF 30+ sunscreen daily and avoid strong sun for several weeks.
- Pause retinoids and exfoliating acids until your doctor clears you, and apply makeup gently from the next day if your doctor agrees.
TCA CROSS vs other scar treatments: how do they fit together?
TCA CROSS treats individual scars, while resurfacing treats the skin around them, so the two are often combined rather than compared.
- Versus a full-face TCA peel: a chemical peel uses much lower concentrations across the whole face for texture and marks. TCA CROSS uses a far higher concentration on a tiny area, which deep scars need.
- Versus punch excision: for scars that are wider or very deep, cutting the scar out and closing it with a fine stitch may be more effective. Your doctor explains which suits each scar.
- With resurfacing: fractional laser or RF microneedling for scars smooths surrounding texture. These are usually scheduled a few weeks apart from TCA CROSS so each area heals fully in between.
For milder, shallow scars, classic microneedling may be enough on its own.
Risks and possible side effects
TCA CROSS uses a strong acid on a small area, and Dr. Hwang will go through its risks with you before you consent:
- Stinging and burning during application, then redness and mild swelling around treated spots.
- Crusting for about a week and pinkness that can last several weeks.
- Post-inflammatory hyperpigmentation : temporary darkening around treated scars, more likely in Asian and darker skin and after sun exposure. It usually fades over weeks to months.
- Lighter spots (hypopigmentation) at treated sites, which can occasionally persist.
- Rarely, a widened scar or new scarring if the acid spreads beyond the scar or healing is disturbed.
- Infection or cold sore reactivation.
Call the clinic if a treated spot becomes increasingly painful or swollen, oozes pus, is still open after two weeks, or if you develop a fever.
TCA CROSS at Hommage Clinic
Hommage Clinic is a women's health and skin clinic in Gangnam, a short walk from Sinnonhyeon Station. TCA CROSS is applied by the physician, scar by scar, after each scar has been examined and matched to the right method. If breakouts are still active, they are treated first, for example withacne laser treatment, and hormone-related acne can be assessed by our OB/GYN team under the same roof. See ourskin and aestheticsservices for related care.
Cost depends on how many scars are treated, the number of sessions and any combined treatments. Cosmetic scar treatment is not covered by Korea's National Health Insurance, although many medical tests and treatments are for enrolled patients. You receive a written quote before treatment, and walk-ins are welcome during opening hours.
How it works
How TCA CROSS works, step by step inside the scar
The idea behind TCA CROSS, first described by Lee and colleagues in Korea in 2002, is simple: concentrate a strong treatment where the scar is and nowhere else. The acid coagulates proteins in the scar walls and floor, which shows as a white frost within about ten seconds. Over the following days a small crust forms and sheds. Underneath, fibroblasts lay down new collagen that gradually fills the scar from the bottom up and pulls its opening narrower.
Each session moves the scar floor up a little. That is why TCA CROSS is planned as a series, with time between sessions for collagen to mature, and why the result is judged months later rather than days.
Candidates
Who is a good candidate for TCA CROSS?
A 2026 review of 34 TCA CROSS publications ranked its usefulness clearly: best for ice pick scars, then boxcar scars, then rolling scars. That ranking follows the shape of the scar. The narrower and deeper the scar, the more of the acid's effect lands where it is needed. Wide, shallow or tethered scars gain little, and spreading strong acid over a wide area raises the risk of a bigger, lighter or darker mark.
Your general health and skin also matter. Good candidates have acne that has been settled for a few months, no active infection or cold sores in the area, and realistic expectations of improvement rather than removal.
Ice pick scars
Narrow and deep; the main use of TCA CROSS.
Narrow deep boxcar
Steep-walled scars that are not too wide.
Wide boxcar
Usually better with resurfacing or punch techniques.
Rolling scars
Tethered from below; subcision suits them better.
Hommage · Gangnam
Hommage Women's Clinic · Gangnam, Seoul
Each scar is assessed before TCA CROSS; not every scar is a good match. Illustrative photo.
Comparing options
TCA CROSS vs TCA peel: why the strength and area differ
People often confuse TCA CROSS with a TCA peel because both use trichloroacetic acid. They are different treatments. A peel spreads a low-strength solution across the whole face to refresh texture and fade marks. TCA CROSS uses a much higher strength on a pinpoint area inside each scar. Published CROSS studies used strengths between 50% and 100%; the 2026 review found no clear gain in results from the highest strengths, but more complications, so strength is chosen for your skin and scar depth.
| Compare | TCA peel | TCA CROSS |
|---|---|---|
| Area treated | Whole face or region | Only inside selected scars |
| Acid strength | Low to medium | High, 50–100% in studies |
| Main purpose | Texture, marks, tone | Lifting narrow, deep scars |
| Recovery | Peeling across the treated area | Small crusts on each scar for about 5–7 days |
| See also | Chemical peels for acne | Ice pick scar treatment |
Recovery
TCA CROSS recovery, day by day
Knowing what is normal makes the first week easier. DermNet, a dermatology reference, describes the frost lasting up to about 12 hours, redness and soreness for 24–48 hours, and a small scab forming after 2–3 days that falls off between days 3 and 7. Pinkness can then linger for several weeks while the new collagen matures.
Hommage · Gangnam
Hommage Women's Clinic · Gangnam, Seoul
Gentle moisturizing helps crusts heal and shed on their own. Illustrative photo.
Aftercare
TCA CROSS aftercare: do's and don'ts
Good aftercare protects both the result and your skin tone. In the 2026 review, most reports of scars getting bigger involved acid spreading beyond the scar or disturbed healing, and dark marks were the most frequent side effect. Leaving crusts alone and avoiding sun are the two habits that matter most.
Do
- Wash gently and pat dry
- Use the ointment or moisturizer you are given
- Apply broad-spectrum SPF 30+ daily
- Wear a hat or stay in shade outdoors
- Let crusts fall off naturally
- Report any spot still open after two weeks
Don't
- Pick or rub off crusts
- Use retinoids or acids until cleared
- Use scrubs or cleansing brushes
- Sunbathe or use tanning beds
- Swim or use saunas in the first days
- Try home TCA products
Asian skin
TCA CROSS for Asian skin: managing the pigment risk
TCA CROSS was developed in Korea and is widely used on Asian skin, but darkening after inflammation remains its most common side effect. Across studies in the 2026 review, temporary hyperpigmentation ranged from 6.7% to over 60%, and it was usually transient. The review also noted that most studies included lighter skin types, so data for darker skin are limited.
To lower the risk, Dr. Hwang may choose a moderate acid strength, space sessions further apart, recommend skin preparation for a few weeks beforehand and ask you to be strict with sun protection. The review suggested longer intervals of about 6–9 weeks for higher strengths or skin that darkens easily.
If a dark mark appears
Most dark marks fade over weeks to months with sun protection alone. If they persist, gentle brightening care or treatments such astranexamic acid therapymay be discussed once the skin has healed.
Hommage · Gangnam
Hommage Women's Clinic · Gangnam, Seoul
A hat and daily sunscreen are the simplest protection against dark marks. Illustrative photo.
Evidence
Is TCA CROSS effective? What the research says
TCA CROSS is one of the better-studied focal scar treatments, with dozens of published series since 2002. The results are consistent in direction: most patients improve, satisfaction is moderate to good, and complete clearance is rare. DermNet summarizes the expected outcome as a one to two grade improvement over about six months.
Satisfaction
Typical range of patient satisfaction across 34 publications and 937 patients.
Stratman & He, J Clin Aesthet Dermatol, 2026Good or excellent
60 patients with ice pick scars after four sessions of 100% TCA CROSS.
Amin et al., J Pak Assoc Dermatol, 2019Satisfied
Of 53 patients after 70% TCA CROSS; 66% had good or excellent improvement.
Dermatol Surg, 2015;41(5)Grades of improvement
Expected change over about six months with correct use.
DermNet, TCA CROSS
Hommage · Seoul
Hommage Women's Clinic · Gangnam, Seoul
Seoul: the clinic is in Gangnam, a short walk from Sinnonhyeon Station. Illustrative photo.
Traveling to Seoul
TCA CROSS in Seoul for international patients
TCA CROSS fits well into a trip to Seoul: the session itself is short, there is no stitching, and the crusts usually settle within a week. Because the full course is typically 2–4 sessions several weeks apart, many visitors either plan two or more trips or have the first session in Seoul and continue the plan with a dermatologist at home using the written notes.
Planning your visit
- Send close-up daylight photos of your scars by WhatsApp, KakaoTalk or the contact form so the doctor can estimate which scars suit TCA CROSS.
- Book the session early in your stay and allow about 7 days for crusts to fall off before flying or important photos.
- Bring your passport, a list of medicines, and tell us if you have taken isotretinoin in the past year or get cold sores.
- Pack a hat and broad-spectrum sunscreen for sightseeing.
Choosing well
How to choose a clinic for TCA CROSS
TCA CROSS is technically simple but unforgiving: a drop too much or a scar chosen poorly can leave a larger mark. Ask these questions at any consultation, including ours:
- Who applies the acid? It should be a physician experienced with focal TCA.
- Which of my scars suit it? A good answer separates ice pick scars from pores and rolling scars.
- What strength, and why? Higher is not automatically better.
- How is acid spread prevented? Fine applicators and small amounts reduce widening risk.
- How is my pigment risk managed? Ask about spacing, preparation and sun care.
- Do I get a written plan and quote? Including session count and alternatives.
What affects the cost of TCA CROSS?
Cost depends on how many scars are treated, how many sessions are planned, and whether resurfacing such asRF microneedlingorfractional laseris added. Cosmetic scar treatment is not covered by Korea's National Health Insurance, and you receive a written quote before treatment.
Hommage · Gangnam
Hommage Women's Clinic · Gangnam, Seoul
You receive a written plan and quote before starting. Illustrative photo.
Your visit
What to expect at your TCA CROSS appointment
01
Scar assessment
The physician examines your skin under angled light and selects the narrow, deep scars that suit TCA CROSS.
02
Preparation
Active acne, isotretinoin use and cold-sore history are checked, and the skin is cleansed and degreased.
03
Application
Acid is pressed into each selected scar with a fine applicator until it frosts, usually in 15–30 minutes.
04
Healing and review
Crusts shed in about a week, and the next session is planned 4–8 weeks later after reviewing each scar.
Your doctor
Dr. Hwang Seonhwa
Physician · Skin & Aesthetic Treatments
Dr. Hwang reserves TCA CROSS for scars that are narrow and deep enough to benefit, applying the acid only inside each scar and leaving the surrounding skin untouched. Each treated scar is reviewed before the next session, and resurfacing is planned separately for the surrounding texture.
Physician for face and skin procedures, including lifting, laser and skin-improvement treatments, planned around facial proportions and skin condition.
TCA CROSS: frequently asked questions
Does TCA CROSS hurt?
Most people feel a sharp stinging or burning sensation for a few seconds to a few minutes as the acid is applied, which a fan or cool compress eases. Numbing cream is rarely needed because only small spots are treated. Afterward, treated scars may feel slightly tender for a day or two.
How many TCA CROSS sessions will I need?
Most people need about 2–4 sessions spaced 4–8 weeks apart, and very deep scars sometimes need more. Each session lifts the scar base a little further as new collagen forms over 2–3 months. Your doctor reviews every treated scar before the next session and may suggest punch excision for scars that do not respond.
How long is the downtime after TCA CROSS?
Downtime is short because only the scars are treated. Each spot turns white, then forms a small dark crust that usually falls off in about 5–7 days. The area may stay pink for several weeks. Most people return to work the next day, using gentle makeup if their doctor agrees.
Is TCA CROSS safe for darker skin?
TCA CROSS is generally well tolerated in Asian and darker skin, because only the inside of each scar is treated and the surrounding skin is left alone. Temporary darkening around treated spots can still occur, so daily sun protection is essential and skin preparation may be recommended beforehand. Tell your doctor if you have had dark marks after previous treatments.
Can TCA CROSS make scars worse?
Rarely. If the acid spreads beyond a narrow scar, too much is applied, or healing is disturbed by picking or infection, a scar can widen or a light spot can form. This is why it is applied by a physician in small amounts with a fine applicator, why wider scars are steered toward other methods, and why aftercare instructions matter.
Can I do TCA CROSS at home?
No. The acid strengths used for TCA CROSS can cause chemical burns, new scars and pigment changes if they are misapplied, and home kits cannot match the control of an in-clinic procedure. Choosing which scars suit TCA CROSS also needs an examination, because large pores, rolling scars and wide boxcar scars need different treatments.
Can foreigners get TCA CROSS in Seoul?
Yes. International patients and foreign residents can book TCA CROSS at Hommage Clinic; bring your passport for registration. Because sessions are usually 4–8 weeks apart, plan return visits or a longer stay, and allow about a week for the crusts to fall away before important events. Please contact us before your visit to arrange language support.
What strength of TCA is used for CROSS?
Published studies have used strengths from 50% to 100%, with 100% the most common. A 2026 review of 34 studies found no clear difference in results between lower and higher strengths, but more complications at higher strengths. Your doctor chooses the strength for your skin type and the depth of each scar.
Does TCA CROSS work on rolling scars?
Usually not well. Rolling scars are wide, soft-edged dips pulled down by fibrous bands, so they respond better to subcision combined with resurfacing. TCA CROSS is best for ice pick scars and narrow, deep boxcar scars.
When will I see results from TCA CROSS?
Once the crusts have fallen off and the pinkness fades, treated scars may already look a little softer, but most of the change builds over about 2–3 months after each session as collagen forms. The overall result of a course is best judged a few months after the last session, compared with photos taken before you started.
Can I have TCA CROSS after isotretinoin?
Tell your doctor exactly when you finished isotretinoin. Some references, such as DermNet, advise avoiding TCA CROSS within 12 months of systemic retinoid treatment because of the risk of healing problems, while practice varies. Timing is decided individually at your consultation.
Can TCA CROSS be combined with laser or microneedling?
Yes. TCA CROSS treats individual scars, while fractional laser or RF microneedling improves the skin around them. They are usually scheduled a few weeks apart so each treated area heals fully before the next step.
Is TCA CROSS the same as a chemical peel?
No. A chemical peel spreads a low-strength acid across the whole face for texture and marks. TCA CROSS uses a much higher strength on tiny areas inside individual scars. Peeling across the face does not occur with CROSS; only the treated scars crust.
References
Sources used for this page, reviewed by Dr. Hwang Seonhwa. Read our editorial and medical review policy.
- Lee JB, Chung WG, Kwahck H, Lee KH. Focal treatment of acne scars with trichloroacetic acid: chemical reconstruction of skin scars method. Dermatol Surg. 2002;28:1017–1021.
- Stratman S, He H. The use of chemical reconstruction of skin scars (CROSS) method with trichloroacetic acid (TCA) for atrophic scars: a comprehensive review. J Clin Aesthet Dermatol. 2026;19(6):52–67.
- Therapeutic response of 70% trichloroacetic acid CROSS in atrophic acne scars. Dermatol Surg. 2015;41(5):597–604. PubMed
- Amin S, Rashid T, Shehzad A, Arshad A, Younas S. Outcome of CROSS technique with 100% trichloroacetic acid in the management of atrophic icepick acne scars. J Pak Assoc Dermatol. 2018;28(4):485–488.
- DermNet. TCA CROSS. Logan I, Elghblawi E; updated 2018.
- Fabbrocini G, Annunziata MC, D'Arco V, et al. Acne scars: pathogenesis, classification and treatment. Dermatol Res Pract. 2010;2010:893080.
This page is general information and does not replace a personal consultation. Illustrations are original works of Hommage Women's Clinic, Gangnam, Seoul; photos marked illustrative are not of patients.
Related acne scar treatments
Ice Pick Scar Treatment
How narrow, deep ice pick scars form and the full plan used to treat them.
Boxcar Scar Treatment
Sharp-edged scars graded as shallow or deep, with the method matched to each.
Rolling Scar Treatment
Wide, wave-like scars that need their tethers released rather than TCA CROSS.
Subcision for Acne Scars
Releases the fibrous bands under rolling scars, often in the same plan as TCA CROSS.
RF Microneedling for Scars
Remodels the skin around treated scars, with lower pigment risk for darker skin.
Microneedling for Acne Scars
Classic collagen induction for shallow scars and overall texture.
Find out which scars suit TCA CROSS
Book an appointment with Dr. Hwang Seonhwa in Gangnam to have your scars assessed and receive a written plan showing which ones suit TCA CROSS and what else may help.
Hommage Clinic · 4F, Building A, 509 Gangnam-daero, Seoul (near Sinnonhyeon Station) · Mon & Fri 10:00–20:00 · Tue–Thu 10:00–19:00 · Sat 10:00–15:00