A naturally occurring glycosaminoglycan found in skin, joints, and connective tissue. HA is one of the most widely used humectants in modern skincare, valued for its water-binding capacity and compatibility with most skin types and formulations.
Hyaluronic Acid (INCI: Hyaluronic Acid, CAS 9004-61-9) is a linear glycosaminoglycan composed of repeating disaccharides of β4-glucuronic acid and β3-N-acetylglucosamine (CIR, 2023). It is found naturally in the skin, connective tissue, synovial fluid, and eyes, and functions primarily as a humectant — drawing moisture from the surrounding environment and helping the skin retain water. The CIR Expert Panel concluded that Hyaluronic Acid and related hyaluronate ingredients are safe as used in cosmetics (2023).
Under ideal laboratory conditions, HA has a very high water-binding capacity (often cited as up to 1,000× its weight), but this theoretical maximum does not directly translate to real-world skin performance, which depends on molecular weight, concentration, formulation, and environmental humidity. The molecular weight of cosmetic-grade HA ranges from 5 to 1,800 kDa. For cosmetic use, HA is derived via bacterial fermentation (using Streptococcus equi subsp. zooepidemicus) or extraction from rooster combs. The CIR Panel noted that bacterially-derived HA is nearly endotoxin-free and preferred over animal sources, which may contain proteins, DNA, and chondroitin sulfate impurities.
According to 2023 FDA VCRP data, Hyaluronic Acid is reported in 663 cosmetic formulations. (Note: Sodium Hyaluronate is a separate INCI ingredient with its own CAS number, reported in 4,713 formulations.) Dermal penetration studies show that molecular weight influences distribution depth — lower MW variants tend to reach deeper into the epidermis, while higher MW variants remain closer to the stratum corneum. However, the CIR Panel emphasised that as a group, hyaluronate ingredients are generally not expected to have significant percutaneous absorption due to their large molecular size. Penetration also depends on the formulation vehicle, skin condition, and application method.
HA has a high water-binding capacity under ideal conditions. In skincare, it helps draw moisture into the stratum corneum and support skin hydration. The actual depth and degree of hydration depend on the product's molecular weight, formulation, and environmental humidity.
By improving skin hydration, HA can reduce the appearance of fine lines caused by dryness. This is a surface-level plumping effect from increased moisture — not a structural change to the skin.
Higher MW HA tends to remain near the skin surface, forming a hydrating film that may help reduce trans-epidermal water loss (TEWL). This film-forming property complements occlusive ingredients in supporting the skin's moisture barrier.
Helps calm irritated skin and supports wound healing. HA plays a natural role in tissue repair and maintaining skin's moisture balance.
Generally suitable for: Most skin types, including dry, oily, combination, sensitive, and acne-prone skin. Individual tolerance may vary depending on the overall formulation and concentration.
The CIR Expert Panel (July 2023) reviewed all available data and concluded that all 7 hyaluronate ingredients — including Hyaluronic Acid — are safe in cosmetics at present practices of use and concentration. EU approved with no restrictions.
In low-humidity environments, using a humectant like HA alone — without an occlusive layer — may feel less effective, as there is less ambient moisture for the humectant to draw upon. Pairing with an occlusive moisturizer (ceramides, squalane, or petrolatum) is standard practice to help lock in hydration.
The CIR Panel (2023) stressed that animal-derived HA (rooster combs) may contain infectious agents, proteins, and endotoxins. Look for bacterially-fermented HA, which is nearly endotoxin-free.
This assessment covers topical cosmetic use only. Cross-linked HA dermal fillers have separate INCI names and are not covered by this safety review. The CIR Panel also noted insufficient data to assess safety via airbrush delivery systems.
The CIR 2023 report reviewed animal developmental and reproductive toxicity studies: subcutaneous injection of HA (up to 60 mg/kg/d) and Sodium Hyaluronate (up to 50 mg/kg/d) in rats and rabbits showed no fetal abnormalities. Oral studies with Sodium Hyaluronate (up to 1,333 mg/kg bw/d) found no maternal toxicity or teratogenicity. As a topical cosmetic ingredient with limited percutaneous absorption, HA is generally considered a low-risk option during pregnancy and nursing. However, these findings are from animal studies — no large-scale clinical trials have specifically studied pregnant human populations. Consult your healthcare provider for personal advice.
Strengthens the skin barrier while HA hydrates. Complementary mechanisms, no conflict.
HA hydrates and plumps; Vitamin C brightens and fights free radicals. Apply Vitamin C first.
Occlusives that seal in the moisture HA delivers. The ideal HA follow-up, especially in dry climates.
HA can help counteract the dryness and irritation retinol may cause. Applying an HA product as a hydrating base layer before retinol is a common approach to improve comfort during retinoid use.
Very low pH products can temporarily reduce HA efficacy. Wait 5–10 minutes between acid and HA application.
In low-humidity environments, using HA without an occlusive layer may feel less effective. Pairing with a moisturizer or occlusive helps ensure more consistent hydration results.
Found in 2,973 product variants in our database. Here are some well-known options:
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