Dermatologic Therapy, Vol. 13, 2000, 173–182Printed in the United States · All rights reserved

Copyright © Blackwell Science 2000

DERMATOLOGIC THERAPY

ISSN 1396-0296

173

Trichloroacetic acid peels

Tri H. Nguyen

&

James A. Rooney

Department of Dermatology, Mayo Clinic, Rochester, Minnesota

Trichloroacetic acid (TCA) holds an importantplace in the armamentarium of chemical peelagents. In low concentrations, TCA is a safe and reli-able preparation for superficial peels (as are glycolicacid and salicylic acid). In higher concentration,50% w/v, TCA may be used as the sole agent for me-dium-depth peels, particularly in those patients forwhom phenol peel is not tolerated or desired. How-ever, it should be noted that TCA used alone inthese higher concentrations has been associatedwith an increased risk of adverse events, includinghypertrophic scarring. As a result, it is now more of-ten used in low concentration for medium-depthpeels, but combined with a pretreatment agent toenhance the depth of penetration. This “combina-tion peel” technique results in a similar beneficialeffect when compared to 50% TCA as a sole agent,but has a better side-effect profile. As an introduc-tion to TCA chemical peels, this article focuses onthe nature of TCA as a chemical peel agent, thetechniques of application, patient satisfaction, andthe avoidance of complications. Combination peelsare briefly discussed in this article. The combineduse of chemical peels with laser treatment is dis-cussed in a subsequent article.

Background

Many chemical agents have been used for peels,including some that are less well known today,such as sour milk, cantharidin, urine, mustard,and sulfur, among others (1). Today the workhorsesof the chemical peel domain are the

a

-hydroxyacids (AHAs), phenol, and TCA. TCA has a partic-ularly long history as an effective agent for ren-dering significant improvement in skin textureand color. It was tested as early as 1882 by P. G.Unna in Germany, and has been the prototype ofchemical peel agents since it was described by

Roberts in 1926 and used for acne scarring byMonash in 1945 (1). Ayres first delineated its useas therapy for aging skin in 1960 (2). With a pro-tein dissociation constant (pKa) of 0.52, TCA isrelatively stronger than the AHAs (the lower thepKa, the stronger the acid). Glycolic acid, in com-parison, has a pKa of 3.83, lactic acid has a pKa of3.86, and citric acid has a pKa of 3.13 (3). TCAlikewise has a greater potential for causing injuryto the skin at a medium or deep level than AHAs,depending upon the concentration and how it isapplied.

A milestone in the study of chemical peels wasachieved with the objective measurement of in-jury depth for each chemical agent used (4). Per-haps no chemical has been more studied in thisrespect than TCA. The terms superficial, me-dium, and deep were developed as a universalgauge of the amount of damage and benefit to beexpected from each chemical peel agent, de-pending upon the type and concentration. Thesuperficial, medium, and deep categories are im-portant because deeper peels offer a more sub-stantial clinical change in skin texture and color,but also generally result in a longer healing timeand a greater risk of more serious complications.

Superficial peels are defined as those causinginjury to the dermis and dermal-epidermal inter-face, and peels using 10–35% TCA as a sole agentgenerally fit into this category. Medium-depthpeels are defined as those that penetrate to thepapillary or upper reticular dermis, and peels us-ing 35–50% TCA as a sole agent or the TCA “com-bination peels” generally fit into this category(Fig. 1). Deep chemical peels are those that causedestruction into the reticular dermis, and TCA asa sole agent is generally not recommended herebecause of potential complications. Complica-tions of TCA peels include dyspigmentation, tel-angiectasias, sensitivity, uneven texture, and scar-ring, among others. Recent studies showing thatthe reticular dermis heals with scarring offer an

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explanation for some of the increased risk associ-ated with use of TCA for deeper peels (5).

Indications for TCA peels

Treatment of photoaging and rhytides, actinickeratoses, lentigines, and other pigmentary dys-chromias are the principle indications for the TCAchemical peel (Fig. 2). It is also occasionally used,but is variably effective, for superficial acne scars(Figs. 3 and 4), postinflammatory hyperpigmenta-tion, melasma, dilated pores, vitiligo, rosacea, seb-orrheic dermatitis, and other conditions (2). Itcompares favorably with 5-fluorouracil (5-FU)cream for the treatment of actinic keratoses, andthe duration of benefit may be longer (Fig. 5). It hasa definite role in improving the fine crosshatchedfacial rhytides and even moderately deep perioralwrinkles, but is not indicated for deeper rhytidescaused by muscles of facial expression or lax skin(2). As with other chemical peel agents, it generallyrenders to skin a more pleasant, smooth, and lessdry or irritated appearance and feel (Figs. 6 and 7).

Mechanism of action andhistologic effects

Application of TCA to the skin causes precipita-tion of proteins and coagulative necrosis of cellsin the epidermis. In higher concentrations itcauses necrosis of collagen in the papillary to up-per reticular dermis. Over several days the ne-crotic layers slough and the skin reepithelializesfrom the germinative segments of hair folliclesthat were spared from chemical damage (Fig. 8).Dermal collagen remodeling after medium-depthpeel may continue afterward for several months(6). The range of injury from lower papillary der-mis to upper reticular dermis (medium to deep)was classically defined by treatment with 40–60%TCA (1). Stegman’s (7) study in 1982 demon-strated that 40–60% TCA produced epidermal ne-crosis, papillary dermal edema, and homogeniza-tion to the midreticular dermis (Fig. 1).

Brodland et al. (8) showed in a porcine model

Fig. 1. Depths of chemical peels.

Fig. 2. Photodamage.

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that a minimum of 30% (w/v) TCA is required forcomplete epidermal necrosis with a single appli-cation, as would be indicated for full treatment ofactinic keratoses. Eighteen percent TCA, theysaid, results in partial epidermal exfoliation thatwould be well tolerated but would also likely offeronly short-term improvement (8). Higher con-centrations, such as

$

40% TCA, may result inmiddermal necrosis. Unlike phenol peels, occlu-sion of TCA does not result in an enhanced depthof necrosis. Rather, at all concentrations, occlu-sion decreases the depth of necrosis, likely due toincreased “interstitial humidification” (8). Occlu-sion is therefore generally not used with TCA, ex-cept as a corrective measure for overtreatment.

Patient satisfaction and the preoperative consultation

The single most prevalent risk of TCA and otherpeels is patient dissatisfaction. In a survey of pa-

tient satisfaction after TCA peel, as many as 30%of patients expressed some disappointment withtheir results (9). Younger and darker-skinnedpatients expressed an even lower satisfactionrate—down to 33% satisfaction in some cases.The authors suggested that the dissatisfactionwas likely related to unrealistic patient expecta-tions. As with all surgical procedures, carefulpreoperative discussion of risks and expectedbenefits contributes greatly to the patient’s for-mation of realistic expectations and their result-ant satisfaction.

Potential complications of TCA as a peeling agent

It has been noted that, “TCA has a split personal-ity: easy to use and forgiving in low (10–30%) con-centrations, it becomes increasingly erratic andunpredictable at concentrations over 35%” (10).

Fig. 3. Post-TCA acne scarring. Fig. 4. Pre-TCA acne scarring.

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At low concentrations of 10–30%, the incidence ofcomplications is also quite low (10). On the otherhand, at the 50% concentration level—commonlyused in proprietary compounds—it is more likelythan many other agents to result in texturalchanges and/or hypopigmentation (1). It mayalso produce an unacceptable incidence of hy-pertrophic scarring, or even full-thickness tissueloss followed by contractile scars (10). The addi-tion of emulsifiers, additives, and surfactants isnot likely to reduce this risk (3). Peeling with 60–75% TCA is very risky and definitely not recom-mended, though spot treatments of actinic kera-toses or other focal hypertrophic lesions may beeffective at these concentrations (1). In general,as TCA concentration rises beyond 35% it has adecreasing benefit:risk ratio, and should be avoidedby the inexperienced practitioner (10). Fortu-nately the advent of “combination peels” has, forthe most part, obviated the need for use of TCA atconcentrations above 35%. Should scarring occur

despite all due diligence to prevent it, “time, sup-port, and intralesional triamcinolone acetonide5–20 mg/ml every three weeks” may be the treat-ment of choice (11). Persistent erythema withdermal induration is a warning sign for the devel-opment of such scarring, and prophylactic topi-cal steroids have been recommended for prophy-laxis should it occur (11). The importance of closefollow-up cannot be overstressed. It should alsobe noted here that any medium-depth peels arerelatively contraindicated in patients who havetaken isotretinoin within the previous 12 months,due to the enhanced risk of scarring in these pa-tients (6).

Though scarring is a rare consequence of TCApeels, other complications are more common.Pigmentary disturbances are the most commoncomplication in all classes of chemical peelingagents—manifested as hypopigmentation and/or hyperpigmentation, and prolonged erythema(12). Hyperpigmentation is generally postinflam-matory and temporary, and often responds wellto tretinoin, bleaching creams, and sun protec-tion (12). Hypopigmentation may occur with TCA,but is more common with deeper peels and Fitz-patrick skin types IV, V, and VI (Figs. 9 and 10).Prolonged erythema of more than 90 days mayrespond to 2.5% topical hydrocortisone, short-term systemic steroids, oral antihistamines, or sil-icone gel sheeting, as well as application of greenfoundation under makeup base (1). Milia arefairly common after medium-depth peels, but areusually easily remedied with minor acne surgery.

Bacterial infections are uncommon, and whenthey occur are often thought to be the result of in-adequate postoperative wound care (12). Woundcultures should be obtained and appropriate an-tibiotic treatment rendered should infections oc-cur. Reactivation of herpes is always a possibility,and should be preempted with appropriate pro-phylactic treatment (12). Suppressive acyclovir ata dose of 400 mg orally twice a day for 2 days pre-operatively and 5–10 days postoperatively hasbeen recommended (6).

Use of combination peels for medium-depth peeling

Due to the risks involved with higher concentra-tions of TCA, the trend in medium-depth peelshas been to combine a lower concentration ofTCA with another less potent superficial peeling

Fig. 5. Actinic keratoses in photodamaged skin.

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agent (3). This approach takes advantage of thediffering mechanisms of action between the com-bination peels. The superficial peeling agent iskeratolytic and disrupts epidermal cohesion, al-lowing deeper penetration of the TCA. Subse-quent application of TCA effects coagulative pro-tein necrosis with greater penetration depth.

The CO

2

plus TCA combination peel

Brody and Hailey (13) reported the use of solidCO

2

ice to injure the epidermal surface prior tothe application of 35% TCA to promote upperdermal injury. The CO

2

plus TCA peel initially ap-plies a hand-sized block of dry ice dipped in ace-tone and alcohol to cause epidermal injury, andis then followed by the application of 35% TCA toextend injury into the dermis. Histologic studieshave shown that this results in damage through thepapillary dermis (1,3). The peel has been shownto be effective for moderate actinic damage, su-perficial hyperpigmentation, and minor wrinkles.Because of the ability to manually focus injurywith the CO

2

pretreatment at the perimeter of de-

Fig. 6. Prepeel TCA photodamage. ↑

Fig. 8. Exfoliation three days post-peel.

Fig. 7. Post-peel TCA photodamage.

→

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pressed scars, this is one of the few peel tech-niques that can also offer focal control of peeldepth, thereby improving the contours of pittedscars (3). The incidence of scarring as a complica-tion of CO

2

and 35% TCA is less than 0.25% (12).

The Jessner’s solution plus TCA combination peel

Dr. Max Jessner combined 14 g each of resorci-nol, salicylic acid, and 85% lactic acid withenough ethanol to make 100 ml of an effective su-perficial peeling agent. After pretreatment of theskin with this solution, 35% TCA can be appliedto extend injury into the dermis, again withoutthe unpredictability of the 50% TCA preparation.It, too, is useful for moderate actinic damage, pig-mentary dyschromias, and minor wrinkles, andalso shows superior results for the blending ofmargins when used in conjunction with deeppeels or laser resurfacing (4). Histologically, Jess-

ner’s plus 35% TCA resulted in a thinner grenzzone and smaller elastotic band than the CO

2

plus 35% TCA combination (2). In one large se-ries, Jessner’s solution and 35% TCA was associ-ated with no scarring complications (12).

The glycolic acid plus TCA combination peel

A 70% glycolic acid superficial peel, followed by 35%TCA to extend injury into the dermis, is anothercombination peel that is effective for medium-depth penetration. It has also been found useful formoderate actinic damage, pigmentary dyschro-mias, and minor wrinkles. Histologic studies showcomparable improvements with the Jessner’s plusTCA peel, with a more narrow grenz zone andelastotic band (2). The technique of application isdifferent, however, in that no cleansing or degreas-ing procedure is used prior to the application of theglycolic acid, and the glycolic acid is neutralizedwith water prior to the application of TCA (4).

Fig. 9. Acne scarring hypopigmentation. Fig. 10. Post-TCA hypopigmentation.

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Procedure for TCA peels

Preparation of the TCA solution

It is critical to standardize the preparation of TCAsolutions. Inconsistent preparations have resultedin inadvertently strong concentrations of TCA so-lution and resultant scarring (14). The weight/volume approach has become the standard in thepublished literature and should be used in almostall circumstances (3). It is important that thismethod not be confused with the weight/weight,weight/100 ml, and dilution of saturated TCAmethods of preparation, as these methods maylead to a higher concentration of the active ingre-dient than was intended (3).

The weight/volume method requires that thedesired concentration in grams of United StatesPharmacopeia (USP) TCA crystals be mixed withenough distilled water to make 100 cc of solution(1). For example, a 35% TCA solution is preparedby diluting 35 g of TCA crystals in distilled waterto make a total volume of 100 cc. In contrast, add-ing 35 g of TCA to 100 cc of water or 35 g to enoughwater to make 100 g of solution are both exam-ples of incorrect preparation methods. Once pre-pared, the solution is stable for at least 6 monthsat either room temperature or refrigerated (1).TCA should be stored in a glass container be-cause it is corrosive to many plastic containers aswell as wax paper covers. Amber or clear glass canbe used, since TCA does not seem to be light sen-sitive. TCA should not be left uncovered, becauseevaporation may cause an increase in concen-tration of the solution. Premixed commercialsolutions of TCA are available, as are paste for-mulations, but they do not seem to offer any ad-vantage to the correctly prepared TCA crystals insolution.

Eye protection

Because chemical peel solutions are caustic to vi-tal structures of the eyes, it is often recom-mended that the eyes be protected prior to initia-tion of the treatment with ophthalmic ointment,gauze pads and tape, or goggles (6), and moni-tored intermittently throughout the procedure. Ifa peel is performed directly to skin around theeyes, great care must be taken in positioning theangle of the head and in application of the solu-tion so that inadvertent seepage of the chemicalinto the eyes is avoided. The head of the patient

may be elevated to a 30 degree angle and a semi-dry applicator used to apply the solution within2–3 mm of the eyelid margin (4). A container ofsterile water should always be available to rinsethe eyes in the event of accidental exposure.

Precleansing

Because facial oils and compact keratin form abarrier to penetration of the peel solution, vigorouscleansing and degreasing is necessary for uni-form penetration of TCA into the skin and for aneven effect. Despite its flammability, acetone con-tinues to be the most commonly used degreasingagent, though rubbing alcohol and other scrubsmay be equally effective (Fig. 11). The patientshould remove makeup, cleanse the face with anantibiotic scrub such as chlorhexidine gluconate,and perform an initial acetone scrub with gauze.This is rarely sufficient, however, and the physi-cian or nurse should perform an additional scrubwith acetone-soaked gauze pads until sebaceousoils have been thoroughly removed from the face(6). A small fan should be used to disperse ace-tone fumes during these steps, and all sources ofheat and flame should be kept at a distance.

Application of TCA

The TCA is applied evenly with cotton-tip appli-cators or saturated 2 in.

3

2 in. gauze pads withsmooth strokes (Figs. 12 and 13). The pads shouldbe wrung out sufficiently to prevent a splash ef-fect that could be injurious to the eyes or causetreatment of unintended areas of skin. The handthat is holding the TCA gauze should be glovedand dry gauze should be held in the other hand toabsorb any excess drip and to avoid inadvertentapplication of the chemical. Since the patient willfeel a moderate sting when TCA is applied, coolcompresses may be applied to each area as it istreated and a small fan may be held and directedby the patient to the uncomfortable area (6). To re-lieve some anxiety, the patient can be reassuredthat once the stinging and burning begins, thesensations are already nearing their peak and a de-nouement should gradually begin. Preoperativesedation is generally not necessary, though lightsedation with a benzodiazepine or narcotic can beused preemptively for an apprehensive patient.

Anatomic subunits of the face are peeled se-quentially, with feathering into the hairline andat the treatment margins. One pattern may begin

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from the forehead to the temples and cheeks, fol-lowed by the lips, nose, and eyelids (4). Often,broad strokes of 2 in.

3

2 in. TCA-soaked gauzeare used for even application to larger regions,and wide strokes with cotton-tip applicators areused for smaller areas (4).

The endpoint of treatment

As the skin is treated, a white color change or“frost” results from epidermal and dermal proteincoagulation (Fig. 14). Some authors feel that mon-itoring this frost (e.g., color intensity and time toclear or fade) is a reliable indicator of peel depth.Others suggest that the depth of injury cannot beappreciated from color alone, and that this indi-cator is unreliable (1). Nevertheless, diffuse red-ness with light cloudy-white frosting that clears in10–15 minutes indicates superficial injury (epi-dermis) and is generally the desired endpoint ofTCA concentrations of less than 35%. A more uni-

form white frost is indicative of epidermal andpapillary dermal injury and is the endpoint for35–40% TCA peels, and also clears over 10–15minutes. A dense, white, uniform frost is indica-tive of deep papillary to reticular dermal injuryand is the endpoint for medium-depth peels with50% TCA alone. This deeper frost usually clears in40–45 minutes (9). A yellow-gray frost representsdeep injury to the mid- to deep reticular dermisand forecasts a prolonged healing time. It gener-ally does not clear even after 40 minutes. AfterTCA is applied, a dry gauze pad should be used toblot (not wipe) the excess from the skin (6).

Reapplication of TCA during the same and subsequent patient visits

When using 50% TCA as a sole agent for medium-depth peels, reapplication during the same pa-

Fig. 12. TCA application with gauze.

Fig. 13. TCA application with Q-tips.

Fig. 14. TCA frost 35 percent.

Fig. 11. Acetone preparation.

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tient visit is usually not recommended, since theeffects are already somewhat unpredictable. Al-though the decision is sometimes made to re-apply TCA to areas with less apparent frost, thisresults in increased protein coagulation andwounding, and is generally unnecessary if thearea was not missed with the first application (1).Reapplication can be useful, however, in selectedsun-damaged areas with impaired penetration,such as those areas with actinic keratoses (1). Re-application on a subsequent visit should notbe performed for at least 6 months, and mostpatients do not require re-treatment for severalyears.

For superficial peels using 10–35% TCA, an evenredness or light whitish film is sought, and reappli-cation to uneven or unresponsive areas during thesame visit is appropriate (1). One practitioner sug-gests that several repeat applications of 15–25%TCA may be performed at 3-minute intervals dur-ing the same visit to induce more erythema andfrost, and improved clinical results (1). These super-ficial peels may safely be repeated at 1- to 2-weekintervals, and are often applied in a series of aboutsix treatments, beginning with low concentrationsand increasing the strength of TCA as tolerated.

Postpeel care

Postoperative care for medium-depth TCA peelsinvolves the application of a thin coat of antibi-otic or Vaseline/Aquaphor ointment three to fivetimes per day after gentle cleansing (Fig. 15). Be-ginning at day 4–5, wet dressings applied twice aday after cleansing may aid in the exfoliation. Ap-plication of ointment between wet dressingsshould be continued, and at no time should a crustbe allowed to form. Reepithelialization should becomplete in 7–10 days, after which applicationof ointment may be discontinued. Thereafter,gentle cleansers, moisturizers, and exfoliationwith routine application of tretinoin or glycolicacid-based maintenance creams are continued.Sun protection must always be stressed to mini-mize postinflammatory hyperpigmentation.

Postoperative care for superficial TCA peels isminimal, and consists of routine gentle cleans-ing. Patients can usually return to their normalactivities promptly, and may use moisturizersand cosmetics to conceal the erythema. Tretinoinusually should not be applied for the first 3–7 daysto avoid further irritation of the healing skin (1).

Conclusion

The preoperative consultation is essential for as-sessing and guiding patient expectations, as wellas determining the appropriateness of chemicalpeels for the patient’s skin. More than one tech-nique and peeling agent is available to achievethe desired depth and benefit. TCA is a valuableagent for both superficial and medium-depthpeels, and its effectiveness has been well demon-strated. Used properly, TCA peels continue to bea safe and reliable method for rendering histo-logic and clinical improvement to the skin. TCA isparticularly safe when used as a superficial peelor in “combination peels” of medium depth. As asole agent in higher concentrations, its predict-ability is less certain and should generally beavoided by the novice practitioner. Since all re-surfacing techniques are quintessentially opera-tor dependent, it is important to develop a thor-ough understanding of and comfort with the

Fig. 15. Postoperative wound care.

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peeling agent. This is best accomplished both bya careful review of the literature and, if possible,by the personalized attention of an experiencedpractitioner.

References

1. Brody HJ. Chemical peeling and resurfacing, 2nd ed. St.Louis: CV Mosby, 1997: 1–14, 60–78, 109–136.

2. Roenigk RK, Resnik SS, Dolezal JF. Chemical peel withtrichloroacetic acid. In: Roenigk RK, Roenigk HH, eds.Dermatologic surgery: principles and practice, 2nd ed.New York: Marcel Dekker, 1996: 1121–1145.

3. Coleman WP, Brody HJ. Advances in chemical peeling.

Dermatol Clin 1997:

15:

19–26.4. Monheit GD. Medium depth chemical peeling. In: Cole-

man WP, Lawrence N, eds. Skin resurfacing. Baltimore:Williams & Wilkins, 1998: 57–70.

5. Hayes DK, Berkland ME, Stambough KI. Dermal healingafter local skin flaps and chemical peels. Arch Otolaryn-gol Head Neck Surg 1990:

116:

794.

6. Otley CC, Roenigk RK. Medium-depth chemical peel-ing. Semin Cutan Med Surg 1996:

15:

145–154.7. Stegman SJ. A comparative histologic study of the ef-

fects of three peeling agents and dermabrasion on nor-mal and sundamaged skin. Aesthetic Plast Surg 1982:

6:

123–135.8. Brodland DG, Roenigk RK, Cullimore KC, Gibson LE.

Depths of chemexfoliation induced by various concentra-tions and application techniques of trichloroacetic acid ina porcine model. J Dermatol Surg Oncol 1989:

15:

967–971.9. Dinner MI, Artz JS. The art of the trichloroacetic acid

chemical peel. Clin Plast Surg 1998:

25:

53–62.10. Duffy DM. Alpha hydroxy acids/trichloroacetic acids:

risk/benefit strategies. Dermatol Surg 1998:

24:

181–189.11. Kotler R. Chemical rejuvenation of the face. St. Louis:

CV Mosby, 1992: 136–179.12. Ragland HP, McBurney EI. Complications of resurfac-

ing. Semin Cutan Med Surg 1996:

15:

200–207.13. Brody HJ, Hailey CW. Medium depth chemical peel-

ing of the skin: a variation of superficial chemosurgery.J Dermatol Surg Oncol 1986:

12:

1268–1275.14. Bridenstine JB, Dolezal JF. standardizing chemical peel

solution formulations to avoid mishaps. great fluctua-tions in actual concentrations of trichloroacetic acid.J Dermatol Surg Oncol 1994:

20:

813.