Quick Comparison
| Glycolic Acid | Tranexamic Acid | |
|---|---|---|
| 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: 2-5% in serum or cream, applied twice daily. Oral (off-label for melasma): 250 mg twice daily — requires medical supervision. Can be combined with other brightening agents. Results visible at 8-12 weeks. Especially effective for melasma. |
| Application | Topical (toner, serum, peel, cleanser). Leave-on products are more effective than wash-off. Apply to dry skin at night. | Topical (serum, cream) or oral (tablets, off-label). Topical preferred for safety. Oral is more effective but carries systemic risks. |
| Research Papers | 9 papers | 10 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.
Tranexamic Acid
Tranexamic acid (TXA) is a lysine analogue that competitively inhibits plasminogen activation—binding lysine-binding sites and preventing conversion to plasmin by tPA and uPA. Plasmin normally activates multiple pathways: converts latent TGF-beta to active form, stimulates keratinocyte release of arachidonic acid and prostaglandins (PGE2, PGF2-alpha), and increases SCF and bFGF—all stimulating melanocyte proliferation and melanogenesis. By blocking plasmin, TXA interrupts this paracrine cascade, reducing melanin through a mechanism independent of tyrosinase. TXA also inhibits VEGF and reduces angiogenesis—addressing melasma's vascular component. May reduce UV-induced plasmin in keratinocytes. This unique mechanism makes TXA synergistic with tyrosinase inhibitors for stubborn melasma.
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.
Tranexamic Acid
Rare
Topical form has minimal systemic absorption and low risk.
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.
Tranexamic Acid →
Originally an oral medication for heavy menstrual bleeding, tranexamic acid (TXA) has emerged as one of the most effective treatments for melasma and stubborn hyperpigmentation that does not respond to conventional treatments. It works through a unique mechanism — blocking plasmin-mediated stimulation of melanocytes — that is different from tyrosinase inhibitors, making it an excellent combination partner.