What are the potential risks associated with hyaluronic acid?

Naturally present in the body, the hyaluronic acid is a polysaccharide of the glycosaminoglycan family. It is found in large amounts in the dermis, around the joints and in the eyes. In the skin, the hyaluronic acid plays mainly a hydrating role. Combined with collagen and elastin fibres in the extracellular matrix, it forms a compressible gel that retains water like a sponge, also allowing its circulation and that of dissolved molecules. It is also found in the epidermis to bind water molecules retained by the hydrolipidic film. However, its concentration decreases over time, partly explaining why the skin becomes drier with age.

This is why hyaluronic acid is highly popular in cosmetics and aesthetic medicine: to compensate for its gradual decline within the skin.

Note : The hyaluronic acid is not limited to its hydrating properties. It also possesses soothing, healing and antioxidant properties, making it a versatile active ingredient suited to various skin concerns.

When applied topically, hyaluronic acid is an active ingredient recognised for its high tolerability.

It is suitable for all skin types, including sensitive, atopic or redness-prone skin. Moreover, this active ingredient is neither irritating, nor allergenic, nor photosensitising, making it a safe option in all seasons, including before exposure to sunlight. European cosmetic regulations do not, moreover, impose a maximum concentration for this ingredient. In practice, formulations generally employ hyaluronic acid at concentrations between 0.1% and 3%, depending on the intended effect. Whether incorporated into a serum, a cream or a mask, it can be used daily with confidence.

The side effects associated with hyaluronic acid are very rare and are limited to mild redness that may correspond to an allergic reaction. A study conducted by Tort and Karakucuk assessed the tolerance of various serums containing 0.5%, 1% or 2% hyaluronic acid of low molecular weight (400 kDa). These serums were applied under occlusion to the forearms of 15 volunteers for periods of 30 minutes, 72 hours, 96 hours and 7 days. No signs of irritation were observed in any participants, even with the higher-concentration formulations or after one week under occlusion. Although the small sample size limits the scope of the conclusions, this study is reassuring regarding the good tolerability of hyaluronic acid.

Hyaluronic acid in topical products is also considered safe for pregnant or breastfeeding women. A review by the Scientific Committee on Consumer Safety (SCCS), an independent scientific panel managed by the European Commission, compiled data from around ten studies on the safety of hyaluronic acid during pregnancy. These studies were performed on rats or rabbits and, in the vast majority of cases, no side effects or foetal abnormalities were observed. However, in one experiment in which rats received up to 60 mg/kg body weight of a 1% hyaluronic acid solution by subcutaneous injection, nodular hyperplasia of the reticular-zone cells was evident in the adrenal glands of the treated mothers.

It is important to place this result in its proper context: this observation originates from a single animal experiment with the product administered by injection rather than topically. To date, hyaluronic acid has been used for several decades in cosmetic products, with no reported adverse effects in pregnant or lactating women, nor in their offspring. Although no clinical study has been conducted in pregnant women for clear ethical reasons, the available data and extensive usage history support its good tolerability. As always, however, it remains preferable to seek the advice of a healthcare professional before any application, particularly on damaged skin or simply if in doubt.

Even though hyaluronic acid is generally very well tolerated, it is still advisable to exercise caution when using a new cosmetic product, including those containing this active ingredient.

Indeed, the full formulation of the treatment may include other ingredients capable of causing reactions cutaneous, particularly in sensitive or allergy-prone skin, such as fragrances, essential oils or alcohols. To minimise any risk, it is therefore recommended to carry out a preliminary test on a small patch of skin, such as the inside of the wrist or elbow, by applying a small amount of the product and monitoring the reaction over 24 to 48 hours. Should redness, itching, burning sensations or any other discomfort occur, do not apply the product to the face or body, as this indicates that your skin cannot tolerate it.

In aesthetic medicine, hyaluronic acid is renowned for producing excellent results, particularly in reducing wrinkles, firming the facial area, or diminishing the appearance of scars. Moreover, according to the French National Agency for the Safety of Medicines and Health Products (ANSM), the adverse effects associated with injections of hyaluronic acid affect only 0.1 to 1% of individuals. The most common are oedema, redness, itching and mild bruising that clear up within a few days. Post-operative complications remain exceptional but do occur. They mainly involve bacterial infections and tissue necroses. These side effects must be addressed promptly to prevent long-term consequences.

Contraindication : Hyaluronic acid injections are not suitable for pregnant or breastfeeding women, individuals on anticoagulants, those with an autoimmune disease, or anyone with a skin infection.

• MASSON F. Acide hyaluronique et hydratation cutanée. Annales de Dermatologie et de Vénéréologie (2010).

• BASENDWH M. A. & al. Complications of hyaluronic acid fillers and their managements. Journal of Dermatology & Dermatologic Surgery (2016).

• TORT S. & KARAKUCUK A. Serum type hyaluronic acid formulations: In vitro characterization and patch test study. Journal of Pharmaceutical Sciences (2021).

• BRAVO B. & al. Benefits of topical hyaluronic acid for skin quality and signs of skin aging: From literature review to clinical evidence. Dermatologic Therapy (2022).

• Cosmetic Ingredient Review. Safety assessment of hyaluronates as used in cosmetics (2023).