Educational guide · 11 min read
Hyaluronic acid (HA) is the most-marketed humectant in modern skincare. It works — but only if you understand molecular weight, why it must be applied to damp skin, and how to layer it with a moisturizer to prevent the opposite-of-intended dehydration effect.
Last updated: August 23, 2026 · Sources: Papakonstantinou 2014, Bukhari 2018, Essendoubi 2016 penetration review
Hyaluronic acid (HA) is a long-chain sugar molecule (glycosaminoglycan, or GAG) that your body naturally produces. About 50% of the HA in your body is in your skin — in the dermis and the spaces between skin cells. HA holds up to 1,000 times its weight in water, which is why it's the primary water-binding molecule in human connective tissue.
In skincare, HA is used as a topical humectant — it draws water from the environment (or from deeper skin layers) into the upper stratum corneum. The native HA molecule your skin makes is large (1,000+ kDa), but skincare products use HA fragments of varying sizes — and the size determines whether the HA stays on the surface or penetrates.
The bottom line: HA is the most effective humectant in skincare, but it must be applied to damp skin and sealed with a moisturizer to work. On dry skin or in dry climates, HA can actually dehydrate you by pulling water OUT of deeper skin layers.
HA is a humectant — a water-attracting molecule. The hydroxyl (-OH) groups along the HA chain bind to water molecules through hydrogen bonding. When applied to the skin, HA:
What HA does not do: it does not stimulate collagen production (that's vitamin C and retinoids). It does not exfoliate (that's AHAs/BHA). It does not treat hyperpigmentation (that's niacinamide and arbutin). HA is purely a hydration molecule — and that's exactly why it's the most important base layer in a routine.
Visible results timeline: immediate for surface smoothing and glow; 2–4 weeks for consistent hydration if used daily; long-term for cumulative barrier support when paired with ceramides.
HA is one molecule, but the broader "HA family" includes 6 formulations you can buy OTC. They differ in molecular weight (size) and penetration depth.
Combines low + medium + high MW HA in one formula. Layered hydration — surface smoothing AND penetration. The modern formulation standard since Bayer 2018.
Try: The Ordinary HA 2% + B5 · CeraVe Hydrating HA Serum · La Roche-Posay Hyalu B5 · Paula's Choice HA Booster · Medik8 Hydr8 B5
Small enough to penetrate the upper stratum corneum. Provides deeper hydration than higher-MW HA. Best for layering under heavier products.
Sits on the surface, draws water in from the air. The most common HA weight in mass-market products. Best for daily hydration under moisturizer.
Try: Bioderma Hydrabio Serum · Most mass-market HA creams
Too large to penetrate. Forms a surface film that smooths and provides immediate plumping. Best for dry or mature skin that needs a topical occlusive effect.
Try: Neutrogena Hydro Boost Water Gel
Chemically broken-down HA fragments that penetrate more easily than native HA. Common in K-beauty and J-beauty. Lightweight feel.
Try: The Ordinary Marine Hyaluronics
The salt form of HA. Slightly smaller and more stable than native HA. Used in most mass-market products because it's cheaper to produce. Effective at surface hydration.
Try: Olay Regenerist Micro-Sculpting Cream · Many Neutrogena HA products
The single most common complaint about HA is "it made my skin drier." Almost always, the cause is incorrect layering. HA is a humectant — it draws water TO the highest-concentration area. If you apply HA to dry skin, the highest water concentration is in the deeper skin layers, so HA pulls water OUT.
Gentle cleanser (CeraVe, La Roche-Posay Toleriane, or Bioderma Sensibio). Pat skin with towel — do not rub dry.
After cleansing, skin should be damp but not dripping. Pat-dry excess water, but leave the surface damp. The window to apply HA before skin air-dries is about 60 seconds.
2–3 drops for the whole face. Press into skin with palms — do not rub. HA will pull the surface water INTO the stratum corneum.
Ceramide-rich moisturizer (CeraVe, La Roche-Posay Cicaplast) to lock the HA-bound water in. HA without sealing evaporates quickly — and takes your skin's water with it.
HA makes the skin temporarily more photosensitive. SPF 50+ in the AM protects against UV-induced free-radical damage to the freshly-hydrated stratum corneum.
Climate caveat: HA works best in humid climates (Bangkok, Singapore, coastal AU). In dry climates (arid, high-altitude, winter heating), HA can pull water FROM deeper skin layers even when applied to damp skin. In dry climates, use heavier occlusive moisturizers (squalane, shea butter, ceramide creams) INSTEAD of pure HA.
Neutrogena Hydro Boost Water Gel (oil-free, mattifying) or The Ordinary Marine Hyaluronics (lightweight, non-comedogenic). Skip heavy creams. Layer HA under a gel moisturizer, not a cream.
CeraVe Hydrating HA Serum or La Roche-Posay Hyalu B5. Multi-MW HA paired with ceramide moisturizer gives the deepest hydration. Layer under a rich cream (CeraVe Moisturizing Cream, not Lotion).
Bioderma Hydrabio Serum or a single-ingredient HA serum with minimal additives. Avoid HA serums with fragrance, essential oils, or multiple actives.
The Ordinary HA 2% + B5 — multi-MW, lightweight, and the B5 supports barrier function without adding heaviness. Apply on damp skin only on cheeks and forehead; skip if T-zone is overly oily.
Multi-MW HA is safe — no irritation, no photosensitivity concerns (beyond standard SPF). CeraVe Hydrating HA or Paula's Choice HA Booster for daily hydration without disrupting the melanin barrier.
Yes. Topical HA is considered safe during pregnancy and breastfeeding — it's a molecule your body already produces, and topical application has minimal systemic absorption. It is one of the recommended hydrators for pregnancy-safe skincare routines (alongside niacinamide, vitamin C, and glycerin).
Almost always one of two reasons: (1) you applied HA to dry skin instead of damp, so it pulled water OUT of deeper layers, or (2) you didn't seal with a moisturizer, so the HA-bound water evaporated. Fix: apply to damp skin within 60 seconds of cleansing, then seal with ceramide moisturizer.
Yes — and you should. HA does not exfoliate, so it doesn't compound retinol irritation. Layer HA on damp skin, then apply retinol, then seal with moisturizer. The HA + ceramide buffer significantly reduces the peeling that comes with the first 6–8 weeks of retinol use.
Sodium hyaluronate is the salt form of HA. It is slightly smaller (better penetration into the upper stratum corneum), more stable in solution, and cheaper to produce. Most skincare products use sodium hyaluronate because of stability. The biological effect is essentially the same.
Yes. Moisturizer contains occlusive and emollient ingredients that seal water IN, but it doesn't add water TO the skin. HA actively draws water into the upper stratum corneum. The combo (HA + moisturizer) gives significantly better hydration than moisturizer alone in clinical trials.
Not really. HA can hold water temporarily, but it doesn't form a barrier to prevent evaporation. In very humid climates (Bangkok, Singapore), HA alone may feel sufficient for a few hours, but a light moisturizer will extend hydration significantly. Don't skip the seal.
These 10 brands are featured on every vitfacts.com comparison page. We track them for ingredient transparency, third-party testing, and Thailand availability.
Since 2013
A clinical-active cult brand built around single-molecule formulas at price points that disrupted the skincare industry. Sold at Sephora, Chemist Warehouse, and most Thai beauty retailers.
Since 2005
A dermatologist-developed US brand built around ceramides + MVE controlled-release technology. Sold at Chemist Warehouse, Watsons, Boots, and most major pharmacies worldwide.
Since 1952
A 70-year-old P&G mass-market skincare brand with clinical retinol offerings in the Regenerist line. Widely stocked at supermarkets, Watsons, Boots, and Chemist Warehouse.
Since 1930
A dermatologist-recommended US brand with a deep retinol catalog (Rapid Wrinkle Repair, Stubborn Texture). One of the most-searched retinol brands on both AU and TH retail sites.
Since 1975
A French pharmacy-grade dermocosmetics brand endorsed by dermatologists worldwide. Their Retinol B3 serum and Redermic lines are bestsellers in both Australian and Thai pharmacies.
Since 1995
A research-driven US skincare brand founded by chemist Paula Begoun. The Clinical 1% Retinol Treatment is one of the most-cited retinol products in dermatology literature. Sold via own site, iHerb, and Sephora.
Since 2009
A UK professional-grade skincare brand built around CSA philosophy (Vitamin C + Sunscreen + Vitamin A). Their Crystal Retinal series is one of the most stable retinaldehyde products on the market.
Since 1977
A French dermo-cosmetic brand under the NAOS group, widely sold at Watsons, Boots, and Thai independent pharmacies. Recently expanded retinol line with the Retinol+C10 serum.
Since 2012
A US premium "biocompatible" skincare brand owned by Shiseido. The A-Passioni 1% Retinol Cream is widely considered the gold standard in the premium retinol segment. Sold at Sephora, Mecca, and iHerb.
Since Thailand (founded year unverified — about/story page does not state a year)
A Thai clinical-skincare brand (อิงกุ) built around ingredient transparency and research-led formulations. Operates two product lines: topical skincare (Green Tea Biome Balance cleansers/creams, Green Tea Retinol Serum Shot, Vitamin C AOX Glowing Serum, broad-spectrum sunscreens) and an oral INU range (astadaily / astanext Astaxanthin + Vitamin E antioxidant supplements).
Why these 10? See the VitFacts editorial policy page (forthcoming) for the criteria — minimum 10 years of documented safety record, public certificate-of-analysis policy, and verifiable Thailand distribution.
Not medical advice. This article is for educational purposes only and does not constitute medical advice. Consult a board-certified dermatologist before starting any new active skincare ingredient, especially if you have eczema, rosacea, or a pre-existing skin condition.