Quick Comparison
| Glycolic Acid | Green Tea Extract (EGCG) | |
|---|---|---|
| Typical Concentration | Daily use: 5-10% at pH 3-4. Weekly peel: 10-30%. Professional peel: 30-70%. Start with 5% every other night. Increase concentration/frequency gradually. Always use SPF — AHAs increase sun sensitivity by up to 50%. Buffered formulations are gentler than free acid. | Topical: 1-5% green tea extract in formulations. Look for products with EGCG specifically listed. Oral: 400-800 mg green tea extract (standardized to EGCG) daily. Apply topical products before sunscreen for additional photoprotection. |
| Application | Topical (toner, serum, peel, cleanser). Leave-on products are more effective than wash-off. Apply to dry skin at night. | Topical (serum, cream, toner) or oral (supplement, tea). Topical is effective for localized skin benefits. |
| Research Papers | 9 papers | 9 papers |
| Categories |
Mechanism of Action
Glycolic Acid
Glycolic acid disrupts ionic bonds between corneocytes (dead skin cells) in the stratum corneum by chelating calcium ions and lowering the calcium concentration at desmosomal junctions. This weakens corneodesmosome integrity and activates endogenous proteases (kallikrein 5 and 7), accelerating desquamation. At higher concentrations, glycolic acid penetrates the viable epidermis and dermis, where it stimulates keratinocyte differentiation and upregulates transforming growth factor-beta (TGF-β) signaling in fibroblasts. This promotes glycosaminoglycan (GAG) synthesis, type I and III collagen production via procollagen gene expression, and elastin remodeling. Its small molecular size (76 Da) and high water solubility give it the deepest penetration of any AHA. The exfoliation also improves barrier function over time by promoting proper corneocyte maturation and reducing stratum corneum compaction.
Green Tea Extract (EGCG)
EGCG scavenges ROS (superoxide, hydroxyl radical, peroxynitrite) and chelates iron/copper that catalyze Fenton reactions. Inhibits MMP-2 (gelatinase A) and MMP-9 (gelatinase B) that degrade collagen types I, III, IV and elastin in photoaged skin — these enzymes are UV-upregulated via AP-1 and NF-kappa B. Reduces sebum by inhibiting 5-alpha reductase type 1 (testosterone to DHT conversion in sebaceous glands). Anti-inflammatory: NF-kappa B inhibition (I-kappa B degradation prevention), COX-2 suppression, TNF-alpha/IL-1beta reduction. Promotes keratinocyte differentiation via involucrin and filaggrin upregulation. Catechol structure enables dual antioxidant and metal-chelating activity. Topical EGCG reduces UV-induced erythema and prevents collagen degradation when used before sun exposure.
Risks & Safety
Glycolic Acid
Common
Stinging, redness, peeling, sun sensitivity. Over-exfoliation damages the skin barrier.
Serious
Chemical burns from professional-strength peels without proper protocol.
Rare
Scarring from improper high-concentration use.
Green Tea Extract (EGCG)
Serious
None topically. Oral high-dose EGCG supplements have rare liver toxicity reports.
Rare
Contact dermatitis.
Full Profiles
Glycolic Acid →
The smallest and most penetrating alpha-hydroxy acid (AHA). Derived from sugarcane, glycolic acid exfoliates by dissolving the bonds between dead skin cells on the surface, revealing smoother, brighter skin underneath. It is the most studied AHA with robust evidence for improving texture, fine lines, hyperpigmentation, and overall skin radiance. The gold standard chemical exfoliant.
Green Tea Extract (EGCG) →
Epigallocatechin gallate (EGCG) is the primary polyphenol in green tea and one of the most potent topical antioxidants. It has been shown to reduce UV damage, decrease sebum production, reduce inflammation, and inhibit the enzymes that break down collagen and elastin. Green tea extract is one of the few antioxidants with evidence for both topical and oral skin benefits.