Microneedling With Glycolic Acid or Trichloroacetic Acid for Atrophic Acne Scars

Atrophic acne scars are a common long-term consequence of acne vulgaris. They may appear as ice-pick, boxcar, or rolling scars and can affect facial appearance and quality of life. Available treatments include microneedling, chemical peeling, laser procedures, dermabrasion, subcision, and other scar-directed interventions. The choice of treatment may depend on scar morphology, skin type, recovery time, cost, and risk of adverse effects.

Microneedling creates controlled microchannels in the skin and may promote dermal remodeling through wound-healing mechanisms, including fibroblast activation and new collagen formation. Glycolic acid is a superficial chemical peeling agent that promotes epidermal exfoliation and remodeling. Trichloroacetic acid produces controlled protein coagulation and a wound-healing response. Combining microneedling with chemical peeling may provide complementary effects on atrophic acne scars.

This single-center randomized controlled study was conducted in the Dermatology and Venereology Department at Kafrelsheikh University Hospitals. A total of 60 adults with atrophic acne scars were allocated equally to one of three groups: microneedling followed by 35% glycolic acid peeling, microneedling followed by 15% trichloroacetic acid peeling, or microneedling alone.

Microneedling was performed with a Dermapen device after topical anesthetic application and skin cleansing. In the glycolic acid group, a 35% glycolic acid peel was applied immediately after microneedling and neutralized according to the clinical endpoint and participant tolerance. In the trichloroacetic acid group, a 15% trichloroacetic acid peel was applied immediately after microneedling until an appropriate frosting endpoint was observed. The microneedling-alone group received no chemical peel. Participants received post-procedure instructions that included sun avoidance, sunscreen use, moisturizer as needed, and topical antibiotic use for 3 days.

Standardized facial photographs were obtained before and after treatment and during follow-up. Two dermatologists who were blinded to treatment allocation assessed clinical response by comparing standardized photographs. The study also collected participant-reported satisfaction, procedure-related pain, post-procedure downtime, and treatment-related adverse effects, including prolonged erythema and post-inflammatory hyperpigmentation.

The study evaluates whether microneedling combined with either 35% glycolic acid or 15% trichloroacetic acid can improve atrophic acne-scar severity more than microneedling alone. It also compares the two combination approaches with respect to treatment tolerance, recovery time, participant satisfaction, and safety.

Inclusion criteria

• Adults of either sex aged 18 years or older.
• Presence of atrophic acne scars of any type or duration.
• Fitzpatrick skin type I to IV.

Exclusion criteria

• Active inflammatory acne lesions, skin infection, or a tendency to develop keloids.
• Immunocompromised state, facial cancer, or severely damaged facial skin.
• Known hypersensitivity to glycolic acid or trichloroacetic acid.
• Oral isotretinoin use within 6 months before enrollment.
• Pregnancy or breastfeeding.
• Inability or unwillingness to adhere to study procedures.
• Unrealistic expectations regarding treatment outcomes.