Hyaluronic Acid Injections versus Topical Application: What are the Differences?

The hyaluronic acid is a glycosaminoglycan with a very high affinity for water. Studies in vitro have even shown that it can capture and retain up to 1000 times its weight in water. Extremely gentle and possessing anti-inflammatory properties, the topical application of hyaluronic acid is suitable for sensitive skin and this active ingredient can even be used to improve the symptoms of certain dermatoses such as eczema and rosacea. Ideal for people with dehydrated skin, the hyaluronic acid strengthens the skin barrier application after application and helps to prevent dehydration fine lines.

When applied topically, the firming and soothing effects of hyaluronic acid are generally observed after 4 weeks, which is the duration of a cellular regeneration cycle. As for its moisturising virtues, these are visible immediately after application and gradually intensify over the weeks. Overall, studies show that hyaluronic acid can increase the hydration of the stratum corneum by about 10%. Several forms of hyaluronic acid can be used in topical application (Hyaluronic Acid, Sodium Hyaluronate, Sodium Hyaluronate Crosspolymer, Sodium Acetylated Hyaluronate...). High molecular weight forms (1000 - 1400 kDa) remain on the skin surface and primarily play a moisturising role, while low molecular weight forms (20 - 300 kDa) can penetrate the stratum corneum, stimulate fibroblasts and have an anti-inflammatory action.

Key Takeaway : Non-irritating and suitable for all skin types, topical application of hyaluronic acid enhances hydration, soothes the skin, and promotes healing.

In aesthetic medicine, the form of hyaluronic acid most commonly used is cross-linked hyaluronic acid. This is achieved by chemically cross-linking hyaluronic acid chains to create a three-dimensional structure, making it particularly resistant to enzymatic degradation. The purpose of cross-linking is indeed toextend the duration of action of hyaluronic acid. More invasive than simple applications of hyaluronic acid, injections also have a broader range of uses. They can be used to fill wrinkles, increase lip volume, redefine facial contours, or even reduce the appearance of certain scars. However, hyaluronic acid injections are contraindicated for pregnant or breastfeeding women, as well as people on anticoagulants, suffering from an autoimmune disease, or presenting a skin infection. Furthermore, exposure to the sun should be avoided in the days leading up to the procedure.

Hyaluronic acid injections are administered into the dermis using a cannula with a rounded tip. Although generally not painful, some individuals may experience a tingling sensation during the injection. To prevent this, dermatologists or aesthetic doctors apply a local anaesthetic cream beforehand. Depending on the extent of the area to be treated, the procedure lasts between 10 and 30 minutes and the effects are visible one to four weeks after the session. As hyaluronic acid is a biodegradable molecule, the results achieved are temporary and typically last between 6 and 24 months. Due to the sensitisation caused by the injections, sun exposure should be avoided for the week following. Although rare, adverse effects are possible, ranging from simple redness, temporary bruising or swelling to tissue necrosis, and even bacterial infections. Early identification and swift intervention significantly reduce the risk of long-term consequences.

Key Takeaway : Relatively invasive, hyaluronic acid injections target numerous skin concerns and deliver good results. However, these results are temporary and the procedure is not without risk.

The choice between applying and injecting hyaluronic acid largely depends on the results you wish to achieve and the price you are willing to pay. Indeed, the cost of a serum, cream, lotion or mask containing hyaluronic acid typically ranges between 10 and 80 euros, whereas an injection can cost between 200 and 500 euros. Considering that multiple sessions may be required to achieve the desired results, it's clear that hyaluronic acid injections require a certain budget. If you simply wish to give your skin a hydration boost, soothe it or aid its healing process, the topical application of hyaluronic acid is sufficient.

However, if you wish to rid yourself of wrinkles, scars or even reduce the dilation of your pores, hyaluronic acid injections are a more appealing option that has proven its effectiveness in numerous studies. It should be noted, however, that this procedure comes with potential side effects detailed above. We advise you to think carefully before taking the plunge and only have it done by a professional you trust.

It is possible tocombine application and injection of hyaluronic acid. These two procedures, cosmetic and medical-aesthetic, are complementary: neither of them can gather all the benefits of their combined action.

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

• BOYD T. & al. Efficacy Evaluation of a Topical Hyaluronic Acid Serum in Facial Photoaging. Dermatology & Therapy (2021).

• GIANNINI A. & al. Multicentre evaluation of a topical hyaluronic acid serum. Journal of Cosmetic Dermatology (2022).