Hyaluronic acid (HA) might be the most misunderstood ingredient in skincare. Despite its name, it has nothing to do with acids that exfoliate — it’s actually a humectant, meaning it attracts and holds moisture. Here’s everything you need to know to use it correctly.
What Is Hyaluronic Acid?
Hyaluronic acid is a naturally occurring sugar molecule (glycosaminoglycan) found throughout your body — in your joints, eyes, and skin. In the skin, it’s responsible for that plump, bouncy, hydrated look. One molecule of HA can hold up to 1,000 times its weight in water, making it the most efficient hydrating ingredient in skincare.
As we age (and with sun damage), our skin’s natural HA levels decline, leading to dryness, fine lines, and loss of plumpness. Topical HA helps restore surface-level hydration — though it works differently depending on the molecular weight of the formula.
Molecular Weight Matters
This is where HA gets interesting. Different sized molecules behave differently on skin:
- High molecular weight HA — sits on the surface, forms a protective film, provides immediate plumpness and smoothness
- Low molecular weight HA — penetrates deeper into the skin, more effective for long-term hydration and fine lines
- Sodium hyaluronate — the salt form of HA, smaller molecule, penetrates more easily, commonly used in serums
The best serums combine multiple molecular weights for both immediate surface hydration and deeper moisturisation.
The Most Common Mistake with HA
Applying HA to dry skin can actually pull moisture out of your skin rather than adding it, especially in dry climates. HA works by drawing moisture from its environment — ideally from the air around it, or from the layers beneath.
The fix: Apply HA to damp skin (just after cleansing, or mist your face with water first), then immediately seal it in with a moisturiser or face oil. This traps the water HA has drawn in and prevents it from evaporating.
How to Layer Hyaluronic Acid
- Cleanse, then leave skin slightly damp
- Apply HA serum and gently press into skin
- Immediately follow with your moisturiser to seal the hydration in
- In the morning, finish with SPF
HA is suitable for morning and evening use. It works beautifully as a base layer under other active ingredients like peptides, niacinamide, or retinol.
Who Should Use Hyaluronic Acid?
Everyone. Genuinely. HA is non-comedogenic (won’t clog pores), fragrance-free in most formulations, and suitable for all skin types including oily, acne-prone, and sensitive. It’s one of the few active ingredients with virtually no risk of irritation.
Hyaluronic Acid vs Sodium Hyaluronate
You’ll see both on ingredient labels. Sodium hyaluronate is the sodium salt of hyaluronic acid — it has a smaller molecular size, penetrates skin more easily, and is more stable in formulations. Both are effective; sodium hyaluronate is often found in higher-quality serums.
Best Hyaluronic Acid Serums
The Ordinary Hyaluronic Acid 2% + B5 is an excellent affordable option that combines HA with Vitamin B5 (panthenol) for extra skin-soothing hydration. The Inkey List Hyaluronic Acid Serum is another budget-friendly choice with multiple molecular weights. For a more premium option, Neutrogena Hydro Boost Serum delivers high-performance hydration at a mid-range price.