Hyaluronic acid in skincare.
Hyaluronic acid (HA) is a glycosaminoglycan that occurs naturally in skin and connective tissue. As a topical ingredient, it's a humectant — it draws and binds water. Different molecular weights penetrate different layers of skin: high-molecular-weight HA sits on the surface providing immediate plumping and hydration; low-molecular-weight HA penetrates deeper for longer-lasting hydration. Many modern serums use a mix of weights.
What it does
Binds water in the skin (up to 1,000× its weight). Provides immediate visible plumping. Improves hydration sustainment over hours. Supports the skin's natural moisture barrier. Useable on every skin type and at every age. The standard hydration intervention in most modern skincare routines.
The evidence
Strong for surface-level hydration; mixed for deeper anti-ageing claims. The plumping and hydration effects are well-documented. Claims about HA driving collagen synthesis or major anti-ageing benefits beyond hydration are weakly supported.
Who should use it
Effectively everyone. Particularly useful for dry, dehydrated, mature, or post-procedure skin. No contraindications. Safe in pregnancy. Useable AM and PM.
What it pairs with
Everything. HA is the most universally compatible ingredient in skincare. Apply to slightly damp skin for maximum hydration draw, then seal with moisturiser. Pairs particularly well with niacinamide (barrier support), retinol (offsets retinol-induced dryness), and peptides.
What to buy in Australia
The Ordinary Hyaluronic Acid 2% + B5 — AU$13, the affordable benchmark. La Roche-Posay Hyalu B5 Serum — AU$50, the pharmacy premium with multi-weight HA blend. Laneige Water Bank Hydro Cream — AU$70, the K-beauty hydration leader.
Frequently asked questions.
- Can hyaluronic acid dry out my skin?
- Yes, in low-humidity environments. HA draws water from wherever it's available — including from deeper skin layers if there's no humidity in the air. Apply to damp skin and always follow with a moisturiser to prevent reverse-osmosis dryness.
- What molecular weight of HA is best?
- A blend of weights. High-molecular-weight HA provides surface plumping; low-molecular-weight HA delivers longer-lasting deeper hydration. Multi-weight serums (La Roche-Posay Hyalu B5, The Ordinary Hyaluronic Acid 2% + B5) are the standard.
- Can I use HA every day?
- Yes, twice a day. No tolerance window required.
- Is hyaluronic acid an anti-ageing ingredient?
- It plumps and hydrates, which softens the appearance of fine lines. It does not drive collagen synthesis or other deeper anti-ageing mechanisms — for that, use retinol or peptides.