Hyaluronic acid: what it is used for and what the scientific evidence says

August 16 2026, 3 min reading time

Hyaluronic acid is one of the ingredients with the most studies behind it. We tell you what the evidence says about its effectiveness and how to use it properly.

Few facial cosmetic ingredients have been studied for as many years as hyaluronic acid. If you're wondering what it's really for and if its reputation is justified, we'll explain it here, based on available evidence, without exaggerated promises.

What is hyaluronic acid?

Hyaluronic acid is a molecule that the skin naturally produces, and its main function is related to water retention. This is why it plays an important role in skin hydration and frequently appears in serums, toners, ampoules, and creams. With age, various natural components of the skin change; in cosmetics, this ingredient is mainly used to provide a feeling of hydration and comfort.

What is it for? What the studies say

Measurable Hydration: A clinical study on a topical hyaluronic acid serum observed improvements in skin hydration measurements during the evaluated period.
Skin Appearance: Some studies on hyaluronic acid formulations and supplementation have evaluated parameters such as hydration, elasticity, and the appearance of fine lines. Results may vary depending on the formula, method of use, and study type.
Tolerance Profile: It is a common ingredient in facial cosmetics, and many formulas are well-tolerated, although the experience may vary depending on the complete product composition and individual sensitivity.

An important nuance: hyaluronic acid applied in cosmetics can provide superficial hydration and temporarily improve the appearance of dehydrated skin. It does not replace medical treatments or clinical procedures; injectable fillers, for example, belong to another category and must be administered by qualified professionals.

How to use it correctly in your routine

Hyaluronic acid can be incorporated after cleansing and before a moisturizer when used in serum or ampoule format. Many people prefer to apply it to slightly damp skin and then follow with a cream for comfort; always follow the usage instructions for each product.

Cleanse your face. Use a product suitable for your skin type and gently remove makeup, sunscreen, sweat, or excess sebum.
Apply a hydrating product. You can incorporate a formula with hyaluronic acid, such as Anua's Heartleaf 77 Toner or Heartleaf 80 Ampoule, following the brand's instructions.
Complete with moisturizer. A cream suitable for your preferences can help finalize your hydration routine. In the morning, apply sunscreen as the last step of your facial care.

The feeling provided by hyaluronic acid depends on the complete formula, the amount applied, and the other products in the routine. If you're looking for more comfort, combining a humectant product with a moisturizer can be a practical alternative.

What skin types can it suit?

Formulas with this ingredient can usually fit into routines for dry, combination, oily, or sensitive skin, as they aim to provide hydration. However, each skin reacts differently: review the ingredient list, introduce new products one by one, and discontinue use if you notice irritation.

In a daily routine, hyaluronic acid can be especially comfortable for those who prefer light, easy-to-combine textures. There's no need to accumulate products: a simple and consistent sequence is usually easier to maintain.

Frequently Asked Questions

Can it be used every day?
It can be used daily if the formula is well tolerated and the manufacturer indicates such use. Always follow the recommended frequency on the packaging.

Does it combine with other active ingredients?
Generally, it can be part of a routine with niacinamide, vitamin C, or other cosmetic ingredients. Introduce new products gradually and avoid adding several intense active ingredients at once if your skin is sensitive.

Why don't I sometimes feel hydration with hyaluronic acid?
The final sensation depends on the formula, the other products you use, and your skin's needs. Applying it within a simple routine and following with a moisturizer can help provide greater comfort.

In summary

Hyaluronic acid has evidence supporting its humectant function and can be a useful option within a hydration-focused routine. Choose a formula that you find comfortable, follow the usage instructions, and complete your daytime care with sunscreen. You can start with our Heartleaf 77 Toner or Heartleaf 80 Ampoule from our Korean facial care collection.