Quick Comparison
| Aloe Vera | Glycerin | |
|---|---|---|
| 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: 2-10% in most products (often higher in moisturizers). Pure glycerin is too sticky — always diluted in formulations. Works best below 20% concentration. No maximum daily use limit. |
| Application | Topical (gel, cream, lotion). Pure inner leaf gel or standardized extracts. Apply to clean skin. | Topical (present in virtually all moisturizers, serums, and toners). Apply as part of regular skincare routine. |
| Research Papers | 10 papers | 9 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.
Glycerin
Glycerin (glycerol) is a small three-carbon polyol (92 Da) that penetrates the stratum corneum via intercellular lipid and transcellular routes. It acts as a humectant through osmotic mechanisms—creating a concentration gradient that draws water from the atmosphere (when humidity >65%) and from deeper epidermal layers. Glycerin upregulates aquaporin-3 (AQP3), a glycerol-permeable water channel in keratinocyte membranes that facilitates water and glycerol transport. It supports the natural moisturizing factor (NMF)—amino acids, lactate, and urea that maintain stratum corneum water-holding capacity. Glycerin modulates keratinocyte differentiation and may enhance lipid lamellae organization. Mild antimicrobial activity occurs through osmotic stress. Clinical studies demonstrate hydration efficacy comparable to or exceeding hyaluronic acid.
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.
Glycerin
Common
Stickiness at high concentrations. May cause mild breakouts in some acne-prone individuals (varies by person).
Serious
None. Extremely safe.
Rare
Allergic reaction is extremely rare.
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.
Glycerin →
The most effective and best-studied humectant in skincare. Glycerin (glycerol) is a small molecule that penetrates the stratum corneum readily, drawing water from the atmosphere and deeper skin layers to hydrate the outer skin. Present in virtually every moisturizer and many serums. Studies show it rivals or outperforms hyaluronic acid for hydration efficacy at a fraction of the cost.