TCA CROSS method explained

A trained clinician cleans the area and uses a fine applicator to place acid into individual depressions, commonly narrow acne scars. The aim is precision: surrounding skin is exposed as little as possible. The acid creates a controlled injury, and the skin’s repair process may gradually improve the depth and edges of the scar.

A treated spot can turn white during application, followed by redness, tenderness, swelling or a crust. The surface appearance changes as the crust separates and fresh skin forms. Improvement is assessed over time, not during the first healing days. Wide, shallow, raised or tethered scars may need a different approach or combination plan.

Share your history of dark marks, delayed healing, cold sores, allergies, keloids, recent procedures and all skin medicines. The clinician may postpone treatment if the skin is sunburned, irritated or affected by active infection.

Follow the written aftercare exactly. Do not rub, peel or scratch treated points. Keep hands and pillowcases clean, avoid swimming and intense heat while advised, and protect the area from sunlight. Do not apply household chemicals or strong exfoliants to make the crust come away faster. Use a bland cleanser and prescribed healing product if recommended.

Call the clinic when discomfort is severe or worsening, redness spreads, the area becomes increasingly hot, or pus, foul odour, fever, marked blistering or unusual swelling appears. Urgent care is needed if swelling affects the eyes, breathing or vision. Ask for review if colour changes persist or the treated area becomes raised.

Ask how the applicator will be controlled, which scars will be treated, whether your current skincare should change, how long each healing stage may last, and how the clinician will decide whether another session is suitable.