Hyaluronic acid is one of the most ubiquitous ingredients in modern skincare — found in moisturisers, serums, toners, and even cleansers. It is also one of the most misunderstood in terms of how it works and what it actually delivers. The marketing around hyaluronic acid tends toward the dramatic (“holds 1000 times its weight in water”). The clinical reality is more nuanced.

What Hyaluronic Acid Is

Hyaluronic acid (HA) is a glycosaminoglycan — a long chain sugar molecule — that is naturally present in large amounts in the dermis, where it plays a critical role in tissue hydration, volume, and structural support. Dermal HA is responsible for much of the plumpness and hydration of young skin; its concentration decreases significantly with age and UV exposure. In injectable form (fillers, skin boosters), HA directly replaces or supplements this dermal reservoir. In topical form, the story is more complicated.

What Topical HA Actually Does

Topical hyaluronic acid primarily works at the skin’s surface and in the superficial epidermal layers. It is a humectant — it attracts water from the environment and from the deeper layers of the skin, drawing moisture to the surface. The result is immediate surface hydration and a plumping effect that is visible but temporary. High-molecular-weight HA (the most common form in products) does not penetrate beyond the epidermis. Lower-molecular-weight HA fragments show some evidence of deeper penetration, but clinical evidence for significant dermal HA replacement via topical application remains limited.

The Important Caveat for Indian Skin

In humid conditions — which apply for significant parts of the year across most of India — topical HA performs well, drawing moisture from the air to the skin surface. In dry, air-conditioned environments, the reverse can occur: HA draws moisture from deeper skin layers to the surface, where it evaporates, leaving the skin more dehydrated than before. This is why HA serum should always be sealed with an occlusive moisturiser, particularly in air-conditioned environments. Applied correctly — on damp skin, sealed with a moisturiser — it is a genuinely effective hydration tool. Applied to dry skin in a dry environment without an occlusive, it can worsen dehydration.

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— Dr. Nishita Ranka | Consultant Dermatologist | Dr. Nishita’s Clinic for Skin, Hair & Aesthetics, Hyderabad