1. What filler with hyaluronic acid actually is
Filler with hyaluronic acid is an injectable gel of cross-linked hyaluronic acid (HA), placed into or under the skin by a trained clinician to add volume or contour. It is a medical procedure, not a serum.
Hyaluronic acid is a glycosaminoglycan found naturally in the dermis, where it binds many times its weight in water. Native HA turns over in roughly a day, so it cannot simply be injected and left to work. Filler manufacturers chemically stabilise it, most commonly with the cross-linker BDDE (1,4-butanediol diglycidyl ether). This turns a runny solution into a cohesive gel that resists enzymatic breakdown for months.
Common injectable products contain roughly 15 to 24 mg/mL of HA, though the figure varies by brand and by indication. Softer, lower-concentration gels are used for fine lines and lips. Firmer, more heavily cross-linked gels are used for cheek or jawline structure. Many products also contain 0.3% lidocaine for comfort. Longevity varies from around six months to two years depending on the product, the site and the individual. Check the manufacturer’s data sheet rather than relying on a clinic’s marketing figure.
Two clinical points matter for anyone comparing options. First, HA filler can be dissolved with the enzyme hyaluronidase, which is why it is considered reversible. Second, risks are real: bruising, swelling and lumps are common and usually transient, while vascular occlusion is rare but serious and needs urgent medical attention. Choose a qualified medical practitioner, and discuss suitability, medications and history with them. Nothing in a skincare article replaces that consultation.
2. Topical hyaluronic acid is not a filler
Many serums are labelled ‘filler’, ‘plumping’ or ‘injectable-style’. Topical HA works on a different layer and by a different mechanism. Applied to skin, HA sits mainly in the stratum corneum, the outer 10 to 20 micrometres of dead keratinocytes. It acts as a humectant and film-former, drawing water into that layer and slowing its loss. The effect is real but temporary: smoother texture and a softer look to dehydration lines. It does not add volume to the dermis or subcutaneous tissue.
Molecular weight is the variable that separates formulas:
- High molecular weight (often above 1,000 kDa): too large to enter the skin; forms a light surface film that reduces water loss and feels cushioned.
- Medium and low molecular weight (roughly 50 to 300 kDa and below): may reach slightly deeper into the upper epidermis. Small, mostly manufacturer-funded studies suggest modest improvements in hydration and the appearance of fine lines, but the evidence is limited.
- Hydrolysed HA or sodium hyaluronate: the sodium salt is the usual form on labels and is functionally the same family. Brands rarely disclose molecular weights, so treat claims about ‘multi-weight’ HA as descriptive rather than proven.
Typical concentrations in serums are 0.1% to 2%. Higher is not better: very concentrated HA products can feel tacky and, applied to dry skin in a dry environment, may leave skin feeling tighter if not sealed with a moisturiser. The ingredient list tells you more than the percentage. HA near the top of the list, above preservatives and fragrance, suggests a meaningful dose, although brands are not required to state the figure.
HA is stable across a wide pH range, roughly 4 to 7, which is where most serums sit. Very low pH formulas can degrade it over time, which is one reason brands avoid combining it with strongly acidic systems. Topical HA also does not extend the life of an injected filler. No good evidence supports that claim, and it is worth being sceptical of anyone selling it that way.
3. Layering order and interactions with other actives
Hyaluronic acid is one of the most compatible ingredients in skincare. It carries no meaningful chemical conflict with retinoids, vitamin C, niacinamide, AHAs or BHAs. The mistakes people make are about sequence, skin dampness and total irritation load, not HA itself.
The general rule is to apply from thinnest and most water-based to thickest and most occlusive. For a morning routine:
- Cleanser.
- Vitamin C serum if you use one. L-ascorbic acid is typically formulated at 10% to 20% and needs a pH below about 3.5 to be effective. Wait a few minutes before the next step.
- Hyaluronic acid serum on slightly damp skin.
- Moisturiser, to seal in the water the HA has drawn in.
- Broad-spectrum sunscreen, SPF 30 or higher, always last.
In the evening, the same logic applies. If you use a retinoid such as retinol (commonly 0.1% to 1%) or adapalene 0.1%, HA can go before or after it. Applying HA first, then the retinoid, then moisturiser reduces irritation for some people by diluting contact, though it may marginally lower delivery. If you use an exfoliating acid such as glycolic acid (typically 5% to 10% at pH 3 to 4) or salicylic acid (0.5% to 2%), use it on a separate night from your retinoid unless a dermatologist has advised otherwise. HA is the hydrating step that follows either.
Where people go wrong is stacking several strong actives and expecting HA to offset the damage. It supports hydration; it does not repair a compromised barrier on its own. If skin is burning, peeling or persistently red, stop the actives and seek advice. Persistent redness or flushing may be rosacea, and itchy, inflamed patches may be eczema, both of which need a dermatologist rather than another serum.
It is hard to judge all of this from front-of-pack claims. Scanning a product barcode in Skin Scan Genius shows how a specific formula sits alongside the retinoid, acid or vitamin C you already use, which is the quickest way to catch a clash before it reaches your face.
4. Skincare before and after injectable filler
If you are having filler with hyaluronic acid injected, your clinician’s aftercare instructions override any general guidance here. They know the product, the site and your skin. Some principles are commonly given, though, and are worth understanding.
Before treatment. Clinicians often ask patients to pause strong exfoliants, retinoids and in-office resurfacing in the days beforehand, because irritated or compromised skin raises the risk of bruising, infection and a poor result. Ask exactly how long, as the window differs between practitioners. Also disclose supplements and medicines that increase bruising, such as fish oil, vitamin E, aspirin or other blood thinners. Do not stop prescribed medication without medical advice.
After treatment. For the first days, skincare is usually kept minimal: a gentle cleanser, a plain moisturiser and sunscreen once any redness has settled and the skin is intact. Many clinicians advise avoiding the treated area with acids, retinoids, scrubs, facial massage and heat-based devices until swelling and tenderness have gone, and avoiding saunas, intense exercise and facials for a period they will specify. Topical HA serum is generally low risk once the skin surface is intact, but check with your practitioner before introducing it.
Reading a label. When you return to actives, reintroduce one at a time. Look at the concentration where it is disclosed, the stated pH range for acids and vitamin C, and the position of fragrance, essential oils and denatured alcohol in the ingredient list. These are common irritants. Introduce a retinoid at the lowest strength, two or three nights a week, and add sunscreen every morning. UV exposure degrades collagen and undermines the results of any injectable treatment.
If a formula does not state pH or percentage, do not guess. Contact the brand, or compare it against your routine in Skin Scan Genius, which flags overlapping actives rather than inventing numbers the label does not give.
Check it against your own routine. Skin Scan Genius reads a product’s full INCI list and flags conflicts with the actives you already use, by skin type and concern.
Frequently asked questions
Is filler with hyaluronic acid permanent?
No. Cross-linked HA filler is gradually broken down by the body, usually over about six months to two years depending on the product, the area treated and individual metabolism. It can also be dissolved earlier with hyaluronidase if needed. Treatment must be repeated to maintain the effect.
Can a hyaluronic acid serum replace dermal filler?
No. A serum hydrates the outermost layer of skin and can soften the look of dehydration lines for hours. It cannot restore lost volume in the deeper tissue, which is what injectable filler does. They address different problems and can be used together.
Can I use retinol or vitamin C after having filler?
Not straight away in most cases. Many clinicians advise waiting until swelling, tenderness and redness have settled before using retinoids, acids or vitamin C on the treated area. The exact period depends on your practitioner and the product used, so follow their written aftercare.
Should hyaluronic acid go on before or after moisturiser?
Before. Apply HA serum to slightly damp skin after cleansing and any water-based actives, then seal it with a moisturiser. Sunscreen comes last in the morning. Putting HA over a thick cream blocks it from reaching the skin surface.
