An Evidence-Based Review

Melasma is a chronic skin condition characterized by symmetric brown or grayish-brown patches primarily on the face, most commonly affecting women with darker skin types. Its treatment remains challenging due to the complex interplay of genetic, hormonal, and environmental factors. Chemical peels are a widely used intervention aimed at exfoliating pigmented skin layers and promoting skin regeneration. This article synthesizes current evidence to determine which chemical peel is best suited for melasma management.

Understanding Chemical Peels in Melasma Treatment

Chemical peels work by applying acidic agents to induce controlled skin exfoliation and regeneration, targeting epidermal and sometimes dermal pigmentation. Peels differ by their active agents and depth of penetration:

• Superficial peels (e.g., glycolic acid, lactic acid) exfoliate the epidermis.

• Medium peels (e.g., trichloroacetic acid or TCA) penetrate to the upper dermis.

• Deep peels (e.g., phenol) affect deeper dermal layers but are less commonly used due to safety concerns.

Comparative Efficacy of Common Chemical Peels for Melasma

Trichloroacetic Acid (TCA) Peels

TCA peels (10–20%, commonly 15%) are medium-depth peels that promote shedding of pigmented epidermal layers and dermal remodeling through collagen stimulation.

• A recent randomized controlled trial reported that 15% TCA peel resulted in the greatest reduction in Melasma Area and Severity Index (MASI) scores, outperforming 15% phenol and 2% glycolic acid peels, with an average MASI score drop of 8.5 points (out of severity scale).

• The TCA peel group also experienced fewer side effects such as redness and irritation compared to phenol and glycolic acid groups, underpinning its favorable balance of efficacy and safety.

Glycolic Acid Peels

Glycolic acid (GA) peels are superficial alpha hydroxy acid (AHA) peels that enhance epidermal turnover and reduce melanin concentration in the upper skin layers.

• Studies comparing 40% GA to 60% lactic acid peels in epidermal melasma found both effective in MASI reduction; however, GA peels exhibited slightly higher side effects including burning and erythema.

• Another study showed 30% GA peels are as effective as 15% TCA peels in reducing melasma severity, though TCA had slightly more adverse effects.

Lactic Acid Peels

Lactic acid (LA), also an AHA, is milder and suitable for sensitive skin.

• In comparative trials, 60% lactic acid peel demonstrated good efficacy with fewer and less severe side effects than glycolic acid peeling for epidermal melasma.

• Lactic acid peels are thus favorable for patients prone to irritation or post-inflammatory pigmentation.

Phenol Peels

Phenol is a deep peeling agent with strong exfoliating and bleaching effects but is less favored in melasma due to high risks of complications. A comparative trial found phenol less effective and with more side effects than TCA and glycolic peels.

Summary Table: Chemical Peels for Melasma

Safety and Treatment Considerations

• Patient Skin Type: Darker-skinned individuals are at higher risk of post-inflammatory hyperpigmentation (PIH) after deeper peels like TCA and phenol. Use of lower concentrations and careful monitoring is crucial.

• Side Effects: Common side effects include transient redness, burning, and peeling. TCA peels may cause more discomfort but provide faster improvement.

• Priming and Post-Care: Use of topical agents such as hydroquinone before and after peeling, strict photoprotection, and moisturization improves outcomes and reduces complications.

• Treatment Regimen: Multiple sessions at 2–4 week intervals yield the best results, with MASI scores typically assessed to monitor progress.

Conclusion

Current evidence indicates that 15% TCA peels offer superior efficacy and safety for melasma treatment compared to phenol and glycolic acid peels, providing rapid and significant reduction in pigmentation with manageable side effects. Glycolic acid peels remain a good alternative, particularly for those with mild melasma or sensitive skin, while lactic acid peels offer a gentler option with fewer side effects. Phenol peels are infrequently used due to higher risk.

Selection of the optimal peel should be individualized based on skin type, melasma severity, and tolerance for downtime, ideally under dermatologist guidance.

References

Dayal, S., & Sahu, P. (2023). Comparative efficacy of 15% trichloroacetic acid, 15% phenol, and 2% glycolic acid in melasma treatment: A randomized controlled trial. Journal of Cosmetic Dermatology, 22(10), 4025–4033. https://doi.org/10.1111/jocd.14988

Khan, M. A., & Ahmed, S. (2019). Comparison of the efficacy and safety of 40% glycolic acid and 60% lactic acid chemical peel in the treatment of epidermal melasma. Journal of Pakistan Association of Dermatologists, 29(4), 332–337. https://doi.org/10.5455/jpad.1427

Sahu, P., & Dayal, S. (2020). Most worthwhile superficial chemical peel for melasma of skin of color: Glycolic acid, trichloroacetic acid, and lactic acid peel comparison. Dermatologic Therapy, 33(6), e14693. https://doi.org/10.1111/dth.14693

Sarkar, R., & Gokhale, N. (2017). Chemical peels in melasma: A review with consensus statements. Journal of Cutaneous and Aesthetic Surgery, 10(3), 123–133. https://doi.org/10.4103/JCAS.JCAS_46_17