TCA Peel

Clinical application guide for trichloroacetic acid peels — 9 strengths (T1–T9) from superficial to CROSS-technique spot treatment

Contraindications

• Active herpes simplex infection at the peel site
• Isotretinoin use within the prior 6 months
• Personal or family history of keloid/hypertrophic scarring
• Fitzpatrick V–VI phototype (relative; limit to T1–T2 only)
• Pregnancy or lactation
• Active dermatitis, eczema, or infection at the intended site
• Facial surgery, laser, or radiation within the prior 3 months
• Immunosuppression (systemic steroids, biologics, chemotherapy)
• Unrealistic expectations or inability to tolerate 7–10 days of downtime
• Uncontrolled diabetes mellitus or cardiovascular disease (for medium-depth)
• Bleeding disorders or active anticoagulation (for medium-depth)
• Open wounds or abrasions at the peel site

Stop Procedure If

1. Prolonged or progressive frosting beyond target endpoint
2. Grey-white dusky discoloration (suggests too deep — possible full-thickness injury)
3. Immediate blistering or epidermal sloughing during the procedure
4. Severe escalating pain disproportionate to the strength used
5. Clinical signs of herpes simplex reactivation (clustered vesicles, prodromal tingling)

Stop the procedure and neutralize with cold water or sodium bicarbonate.

• Photoaging
• Melasma
• Acne Scars (CROSS)
• Pigmentary Dyschromia
• Fine Rhytides
• Seborrheic Keratoses

1. 01

   Cleanse & Degrease

   2–3 min

   Cleanse with gentle non-residue cleanser to remove makeup, sunscreen, and surface impurities. Degrease thoroughly with acetone or 70% isopropyl alcohol on gauze until the skin squeaks.

   • Uniform degreasing is critical for even TCA penetration. Uneven degreasing is the leading cause of patchy frost and unpredictable depth.
2. 02

   Patch Test

   10 min

   First session only: apply a small amount of TCA 25% behind the ear or on the inner forearm. Observe for 10 minutes for adverse reaction.

   • First session only. If erythema, itching, swelling, or prolonged frost occurs, do not proceed.
3. 03

   Apply TCA 25% (T2)

   3–5 min

   Using a fan brush or folded gauze, apply 1–2 layers of TCA 25% in a thin, even coat. Work systematically: forehead, temples, cheeks, nose, chin, upper lip. Avoid eyelids, lip vermilion, and nostrils.

   • Canonical T2 (25%) protocol. For T1 (15%) reduce to 1 layer; for T3–T4 refer to the standalone strength switcher and use only if formally trained in medium-depth peeling.
4. 04

   Observe Frost Endpoint

   3–5 min

   Monitor continuously for the Level I–II pink-white frost endpoint (Obagi classification) — blotchy speckled white frost with underlying pink showing through. Contact time 3–5 minutes.

   • Target endpoint for T2: Level I–II. Do NOT pursue Level III (dense opaque white frost) with 25% — that is medium-depth territory and requires 35% TCA + Jessner's or formal medium-depth training.
5. 05

   Neutralize / Settle

   10 min

   TCA is self-limiting — once the frost reaches target depth, the reaction stops on its own. Apply cool water compresses for 10 minutes to reduce stinging and calm the skin.

   • No chemical neutralizer is needed for TCA. Cool compresses provide symptomatic relief only.
6. 06

   Post-Peel Care & Discharge

   3–5 min

   Apply bland emollient (petrolatum or ceramide cream) and SPF 50+ sunscreen. Provide written post-care instructions. Prescribe valacyclovir 500mg BID × 5 days for patients with HSV history (started 1 day pre-peel per Rendon 2010).

   • Strict photoprotection for 4 weeks. No picking, scrubbing, or makeup until re-epithelialization (day 7–10 for superficial).

This in-app guide reflects the canonical T2 (25%) protocol. For full per-strength protocols across all 9 variants (T1–T9) including CROSS technique details and frost endpoint references, see the standalone strength switcher at /docs/tca-peel-procedure-guide.html.