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How Trichloroacetic Acid (TCA) Reduces Acne Scars (and May Also Help with Acne)

Trichloroacetic Acid Reduces Scars by Promoting the Production of Collagen (and May Help Acne by Exfoliating the Skin)

By: Dan Kern, Acne.org Founder & CSO
Last updated: July 08, 2019

The Essential Information

Trichloroacetic acid (TCA) is an acid used for the treatment of acne scars, most notably icepick scars. It works to treat acne scars by increasing the production of a skin protein called collagen, which fills in the indention left by the scar. The procedure is performed by a doctor or nurse who puts some TCA on the tip of a toothpick and presses it into each icepick scar one by one. This creates a frosting on the skin and scabbing in the days after the procedure. It must usually be repeated several times to achieve a desired correction in icepick scars.

Trichloroacetic acid is also sometimes used as an all-over peel to reduce rolling or boxcar scars.

It may also be useful in the treatment of acne because it has exfoliating properties, which may help to unclog pores, but from the one study performed thus far, it appears to be less effective than a salicylic acid chemical peel for this purpose.

The Science

Introduction to TCA

Trichloroacetic acid (TCA) is an acid mainly used for the treatment of acne scars, and not acne itself. However, certain properties of TCA may enable it to treat acne. Since TCA is used for the treatment of acne scars, there are not many studies on its effectiveness to treat acne. One study found that TCA can clear acne to some extent, but is not the best acne treatment. So in practice, TCA is most effective for the treatment of acne scars.1-3

How TCA Works on Acne Scars

There are three main types of atrophic acne scars, which leave depressions in the skin.

  1. Icepick scars (most common): Doctors treat icepick scars by spot treating them one by one with the TCA CROSS method.
  2. Rolling scars: All-over TCA peel is sometimes used.
  3. Boxcar scars: All-over TCA peel is sometimes used.

Icepick Scars

How acne scars develop

Some people are more genetically prone to develop acne scars and respond to an acne lesion with an overly-prolonged inflammatory reaction, which results in a loss of collagen that leaves a permanent depression in the skin.

How TCA CROSS works to treat icepick scars

TCA is most often used to treat icepick scars through a series of steps:

  1. A doctor applies TCA to the tip of a toothpick and presses it firmly into each icepick scar one by one. After application, TCA initially works by causing skin proteins to stick to each other, causing cell death and creating a "white frost" appearance on the skin.
  2. A few days after treatment, the dead skin cells form a crust on the surface of the skin that look like small scabs.
  3. The crust falls off the skin, which reveals newly formed skin layers. This forces the skin to produce more collagen, which can fill in the depression caused from the scar.

Icepick scars are usually deep, and TCA is unlikely to immediately eliminate them. It usually take multiple treatments over the course of months before an acne scar will refill with collagen to an acceptable degree.

Treating Acne Scars with TCA

TCA Side Effects

Trichloroacetic acid can cause mild side effects, including:

  • Skin discomfort
  • Mild or moderate stinging pain
  • Skin redness
  • Skin discoloration (mainly in darker-skinned individuals)

Since high-concentration TCA can cause people with darker skin to develop dark marks, darker-skinned people should use caution when using high-concentration TCA.1,4

Since high-concentration TCA can cause people with darker skin to develop dark marks, darker-skinned people should use caution when using high-concentration TCA.

Efficacy of TCA on Acne Scars

Researchers have performed several studies investigating the effectiveness of TCA on the treatment of acne scars, both using the TCA CROSS method and as an all-over peel.

Expand to read details on studies about the TCA CROSS method

Dermatologic Surgery

A 2002 study published in Dermatologic Surgery investigated the effect of a 65% or 100% TCA to treat acne scars. Researchers performed six TCA sessions over the course of six months at either 65% or 100% concentration to indented acne ice pick scars in 65 patients. For the 65% TCA treatment, 40% of patients reported good or excellent improvement of acne scars after the third treatment, which increased to 100% after the sixth treatment. For the 100% TCA treatment, 88% of patients reported good or excellent improvement of acne scars after the third treatment, which increased to 100% of patients reporting excellent improvement after the sixth treatment. Therefore, the researchers concluded that TCA is able to improve acne scars.4

Journal of Cutaneous and Aesthetic Surgery

A 2010 study published in the Journal of Cutaneous and Aesthetic Surgery investigated the effect of a 100% TCA treatment to treat ice pick acne scars in 10 patients over four treatment sessions. After the four sessions, the researchers found that 8 of the 10 patients saw 70% improvement in their acne scars, while the remaining 2 patients saw a 50 - 70% improvement in their scars.1

Egyptian Journal of Dermatology and Venereology

A 2013 study published in the Egyptian Journal of Dermatology and Venereology investigated the effect of a 50% TCA treatment on all three types of atrophic acne scars in 30 patients over three treatment sessions. The researchers found that the 50% TCA treatment was most effective at treating ice pick acne scars, followed by boxcar scars, and then rolling scars.6

Indian Dermatology Online Journal

A 2014 study published in the Indian Dermatology Online Journal investigated the effect of a TCA treatment combined with surgical subcision, which is a small incision on the surface of the skin, to treat all three types of atrophic acne scars in 12 patients. Generally, TCA treatments are most effective at treating ice pick scars, and are less effective at treating boxcar or rolling scars. This research found the combination of a TCA treatment with surgical subcision effectively treated ice pick, boxcar, and rolling scars. In this small study, results were graded as excellent, good, and fair in six, three, and one patients, respectively.3

Expand to read details on a study about an all-over TCA peel

Journal of Cutaneous and Aesthetic Surgery

A 2014 study published in the Journal of Cutaneous and Aesthetic Surgery investigated the effect of a 15% TCA peel to clear acne scars when used over the entire face instead of as a spot treatment. To perform this study, the researchers applied the 15% TCA peel every two weeks for six peeling sessions in 50 patients with atrophic acne scars. The researchers found that all 50 patients reported at least some improvement in acne scars, but that the most significant improvement occurred in patients who began the study with less severe scars.7

How TCA May Work on Acne

Acne is a disease that begins with clogged pores. Chemical peels are acids that work by exfoliating the top layer of accumulated dead skin cells, increasing skin turnover, and reducing clogged pores. There are several types of acids used in chemical peels, most notably glycolic acid and salicylic acid, and TCA likely works in similar ways to these other acids. However, because TCA is not typically used in chemical peels for acne, we don't have enough concrete evidence to know for certain how TCA works if it is applied as an all-over chemical peel treatment for acne.

Researchers have only performed one study on the ability of TCA to treat acne.

Dermatologic Surgery

A 2015 study published in Dermatologic Surgery compared the effectiveness of a 25% TCA peel to that of a 30% salicylic acid peel. Salicylic acid is a common acne treatment. This was done as a split-face study every two weeks for two months. This study found that 85% of 20 patients reported some level of acne improvement, while 95% of 20 patients reported some level of acne improvement. However, the researchers did find that the TCA peel was better than salicylic acid at treating non-inflammatory lesions like whiteheads and blackheads, improving them in 80% of patients. Therefore, they concluded that, overall, TCA is less effective than salicylic acid.5

Summary

Trichloroacetic acid (TCA) is a chemical treatment applied by a professional for the treatment of acne scars. It works to treat acne scars by stimulating the production of the skin protein, collagen, which helps to fill in the depression caused by them. Little is known about using TCA to treat acne, but research investigating the effect of TCA on acne has found, through only one study, that TCA is somewhat effective at clearing acne. However, it is less effective than salicylic acid.

References:

  1. Bhardwaj, D. & Khunger, N. An assessment of the efficacy and safety of CROSS technique with 100% TCA in the management of ice pick acne scars. J Cutan Aesthet Surg 3, 93 - 96 (2010).
  2. Fabbrocini, G. et al. Acne scars: Pathogenesis, classification and treatment. Dermatol Res Pract 2010, 1 - 13 (2010).
  3. Kaur, J. & Kalsy, J. Subcision plus 50% trichloroacetic acid chemical reconstruction of skin scars in the management of atrophic acne scars: A cost-effective therapy. Indian Dermatol Online J 5, 95 - 97 (2014).
  4. Lee, J. B., Chung, W. G., Kwahck, H., Lee, K. H. & Monheit, G. Focal treatment of acne scars with trichloroacetic acid: Chemical reconstruction of skin scars method. Dermatol Surg 28, 1017 - 1021 (2002).
  5. Abdel Meguid, A. M., Elaziz Ahmed Attallah, D. A. & Omar, H. Trichloroacetic acid versus salicylic acid in the treatment of acne vulgaris in dark-skinned patients. Dermatol Surg 41, 1398 - 1404 (2015).
  6. El Garem, Y. F., Ghabrial, E. E. & Embaby, M. H. Chemical reconstruction of skin scars technique using trichloroacetic acid in different types of atrophic acne scars. Egypt J Dermatol Venereol 33, 37 - 41 (2013).
  7. Garg, S. & Baveja, S. Combination therapy in the management of atrophic acne scars. J Cutan Aesthet Surg 7, 18 - 23 (2014).

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