Can TCA CROSS make scars worse?

By Dr Magnus Lynch
MA(Cantab) DPhil(Oxon) MRCS FRCP
Consultant Dermatologist & Dermatological Surgeon
Last updated 2026-08-08

TCA CROSS can make a scar wider, however this is not the same as making it worse. A scar that becomes wider but shallower is usually less noticeable, since what makes a deep scar conspicuous is its depth and the shadow it casts rather than its width. The complication that genuinely matters is pigmentary change, and in particular loss of pigment.

The treatment works by creating a chemical burn at the site of the scar so that it heals from the bottom upwards. As the base lifts, the scar tends to broaden and flatten, trading a narrow deep pit for a shallower and more open depression which catches far less shadow. For ice pick scars and deeper boxcar scars this trade is the entire purpose of the procedure, and it is why the treatment works on scars that resurfacing cannot reach.

Pigmentary change is an important risk. Increased pigmentation following treatment usually settles over months and can be treated. Loss of pigment is the more difficult outcome, since a pale mark may be permanent and is hard to correct. It is often assumed that this is a problem confined to darker skin types, however it can also occur in patients with lighter skin types.

The risk is reduced by treating a small number of scars first as a test and waiting to observe how they heal, by using small and precisely placed volumes rather than treating many scars quickly, by staging treatment across several sessions, and by avoiding the procedure entirely in anyone with a history of keloid scarring.

I perform TCA CROSS regularly and I will always advise treating a smaller number of scars as a test first, and I would be cautious of any clinic that does not, since the healing response is individual and a test session establishes how a particular patient's skin will behave before any wider commitment is made.

Related Articles

• Will TCA CROSS work for my ice pick scars?
• Which acne scars can be cut out rather than resurfaced?
• What order should acne scar treatments be done in?
• How are acne scars classified and what treatments are available?

About Dr Magnus Lynch

MA(Cantab) DPhil(Oxon) MRCS FRCP

I am a London-based Consultant Dermatologist and Dermatological Surgeon. I am highly experienced in skin cancer diagnosis, Mohs micrographic surgery, acne, rosacea, acne scarring and laser treatments. I studied at the Universities of Cambridge and Oxford, and completed my dermatology training and Mohs fellowship at the prestigious St John's Institute of Dermatology. I graduated from medical school in 2003 and have worked exclusively in Dermatology since 2012.

I lead a research team at King's College London investigating the molecular biology of skin cancer. In recent years I have been involved in Media Appearances, including the Channel 5 series 'Skin A&E', where I perform skin surgeries and treat various skin conditions.

My NHS practice is at Guy's Hospital. I consult with private patients at OneWelbeck (near to Bond Street station) and on Harley Street. Book A Consultation.