Quick Comparison
| Aloe Vera | Lactic Acid | |
|---|---|---|
| Typical Concentration | Apply pure aloe vera gel or products containing high concentrations (>50% aloe). For sunburn: apply liberally and frequently. For daily use as a soothing moisturizer: apply after cleansing. Refrigerating aloe gel provides additional cooling relief. | Concentrations: 5-12% for daily use. 30-50% for professional peels. Start with 5% every other night. The Ordinary offers 5% (gentle) and 10% (moderate) options. Always use SPF during the day. |
| Application | Topical (gel, cream, lotion). Pure inner leaf gel or standardized extracts. Apply to clean skin. | Topical (serum, peel, toner). Apply to dry skin at night. Follow with moisturizer. |
| Research Papers | 10 papers | 10 papers |
| Categories |
Mechanism of Action
Aloe Vera
Acemannan (acetylated mannan polysaccharide) is the primary bioactive—it binds to macrophage mannose receptors and stimulates macrophage phagocytosis, cytokine release (IL-1, TNF-α), and fibroblast proliferation via growth factor induction, accelerating wound healing and granulation tissue formation. Acemannan also promotes keratinocyte proliferation and migration. Aloesin (a chromone) inhibits tyrosinase and tyrosinase-related protein-1 (TRP-1), providing mild brightening. Aloe-emodin has antibacterial activity against Gram-positive bacteria and antiviral effects. Salicylic acid naturally present in aloe inhibits cyclooxygenase (COX), providing mild anti-inflammatory and analgesic effects. The gel matrix forms a semi-occlusive film that reduces transepidermal water loss (TEWL). Aloe contains glucomannan, which acts as a humectant. Proteolytic enzymes (bradykinase) may contribute to anti-inflammatory activity. Use inner leaf gel to avoid anthraquinones in the latex that can cause irritation.
Lactic Acid
Lactic acid (90 Da, larger than glycolic acid) exfoliates via the standard AHA mechanism: chelating calcium at corneodesmosomes and promoting desquamation through protease activation. Unlike glycolic acid, lactic acid is a natural component of the skin's natural moisturizing factor (NMF) and functions as a humectant, drawing water into the stratum corneum through hygroscopic binding. It inhibits tyrosinase enzyme activity in melanocytes, providing mild brightening. At higher concentrations (10%+), lactic acid upregulates serine palmitoyltransferase and glucosylceramide synthase in keratinocytes, stimulating ceramide synthesis and improving barrier lipid composition. It also enhances filaggrin proteolysis to NMF components. This dual action—exfoliation plus barrier support—makes it the most moisturizing AHA and clinically useful for dry, sensitive, or barrier-compromised skin.
Risks & Safety
Aloe Vera
Common
May cause drying if used alone (aloe lacks occlusive properties, so moisture can evaporate).
Serious
None from topical use.
Rare
Allergic contact dermatitis (especially to compounds in the latex/outer leaf, not the inner gel). Oral aloe vera is a separate concern with laxative effects.
Lactic Acid
Common
Mild stinging, redness — less than glycolic acid at equivalent concentrations. Sun sensitivity.
Serious
None at cosmetic concentrations.
Rare
Over-exfoliation with daily high-concentration use.
Full Profiles
Aloe Vera →
One of the oldest and most recognized soothing ingredients, used for millennia for burns, wounds, and skin irritation. Aloe vera gel contains over 75 active compounds including polysaccharides, vitamins, minerals, and enzymes. It provides immediate cooling, hydration, and anti-inflammatory relief. The evidence is strongest for wound healing, sunburn recovery, and moisturization.
Lactic Acid →
A gentle AHA derived from milk that provides chemical exfoliation plus hydration — a unique dual benefit. Lactic acid has a larger molecular size than glycolic acid, so it penetrates more slowly and causes less irritation, making it ideal for sensitive skin and AHA beginners. It also has humectant properties, drawing moisture into the skin as it exfoliates.