An Evidence-Based Review

Acne scars are a common and often distressing consequence of moderate to severe acne. Chemical peels are a popular dermatological procedure touted for their ability to improve skin texture and reduce the appearance of scars. But how effective are they for acne scars, and what does the evidence say?

How Chemical Peels Work

Chemical peels use acids or other chemicals to exfoliate the top layers of skin, stimulating new skin growth and collagen production. This process can smooth the skin’s surface and lighten pigmentation, making scars less noticeable.

Types of Chemical Peels for Acne Scars

Chemical peels are classified by their depth of penetration:

Superficial peels are generally less effective for deep acne scars but can help with mild discoloration and textural irregularities. Medium and deep peels penetrate further and are more effective for moderate to severe atrophic (depressed) scars.

Evidence for Chemical Peels in Treating Acne Scars

Superficial Peels

• Glycolic Acid (AHA) and Salicylic Acid (BHA):
  These peels can improve mild acne scars and post-inflammatory hyperpigmentation. Studies show that concentrations of 30–70% glycolic acid and 30% salicylic acid, performed in a clinical setting, can reduce the appearance of superficial scars after several sessions.

• Lactic and Mandelic Acid:
  Gentler acids like lactic and mandelic are suitable for sensitive skin and mild textural issues, but are less effective for deeper scars.

Medium and Deep Peels

• Trichloroacetic Acid (TCA):
  TCA peels, especially when used in the CROSS (Chemical Reconstruction of Skin Scars) technique with high concentrations (65–100%), have demonstrated significant improvement in atrophic acne scars, particularly ice pick scars. Multiple studies report that 70% or more of patients experience good to excellent improvement after several treatments.

• Jessner’s Solution:
  Often combined with TCA, Jessner’s solution enhances penetration and efficacy for moderate scarring.

• Phenol Peels:
  Deep phenol peels are rarely used due to higher risks and side effects, and are generally less favored compared to laser resurfacing for severe scars.

Clinical Outcomes and Limitations

• Effectiveness:
  Chemical peels can significantly improve the appearance of mild to moderate atrophic scars and post-acne pigmentation. They are less effective for deep, hypertrophic (raised), or keloid scars.

• Comparative Efficacy:
  Microneedling and laser treatments often outperform chemical peels for deeper scars, but peels remain a valuable option for patients seeking less invasive or more affordable treatments.

• Skin Type Considerations:
  Chemical peels are generally safe for lighter skin tones. Darker skin types may experience post-inflammatory hyperpigmentation, though careful agent selection and professional supervision can minimize risks.

Safety and Side Effects

• Common Side Effects:
  Redness, peeling, temporary darkening, and sensitivity are expected. Medium and deep peels carry higher risks, including prolonged redness, pigment changes, and, rarely, scarring.

• Aftercare:
  Sun protection and proper skincare are essential after a peel to prevent complications and optimize results.

Conclusion

Chemical peels can reduce the appearance of acne scars, especially mild to moderate atrophic scars and post-inflammatory pigmentation.
Medium and deep peels, particularly those using TCA, are most effective for deeper atrophic scars. However, chemical peels are less effective for raised or very deep scars, where other treatments may be preferred. Always consult a dermatologist to determine the best approach for your skin type and scar severity.

Key Takeaways:

• Chemical peels improve mild to moderate acne scars and pigmentation.

• TCA peels (especially with the CROSS technique) are most effective for atrophic scars.

• Multiple sessions are usually required for best results.

• Deeper scars may need alternative treatments like microneedling or lasers.

• Professional assessment is essential for safety and optimal outcomes.