Biostimulatory Fillers: Sculptra and Radiesse Explained

Part of our complete guide to Dermal Fillers.

Last updated: 5 March 2026

While hyaluronic acid fillers dominate the dermal filler market, and for good reason, they are not the only option. Biostimulatory fillers represent a fundamentally different approach to facial rejuvenation: rather than simply adding volume, they stimulate your body to produce its own collagen. This provides gradual, natural-looking improvement that can last significantly longer than traditional fillers. Sculptra and Radiesse are the two most widely used biostimulatory products, and understanding how they work helps determine whether they might be right for you.

What makes biostimulatory fillers different?

Traditional hyaluronic acid fillers work by physically occupying space in the tissue. They provide immediate volume where they’re placed, integrating into the tissue and attracting water to maintain their hydrating, volumising effect. When they’re metabolised (broken down by the body), the volume they provided disappears.

Biostimulatory fillers work on a fundamentally different principle. While they may provide some immediate volumising effect, their primary mechanism is triggering the body’s own collagen production, a process called neocollagenesis. The injected material acts as a scaffold that stimulates fibroblasts (the cells responsible for collagen production) to lay down new collagen fibres around and through the product. Over weeks to months, as the product is gradually absorbed, it is replaced by your own newly produced collagen.

This means results develop gradually, often over three to six months, rather than appearing immediately. The trade-off for this delayed gratification is results that can look exceptionally natural and last considerably longer than HA fillers, as the improvement is based on your own tissue rather than an injected substance.

Sculptra: Poly-l-lactic acid (PLLA)

Sculptra contains poly-L-lactic acid (PLLA), a biocompatible, biodegradable synthetic polymer that has been used in medicine for decades, most famously as the material in dissolvable sutures. When injected into the deep dermis or subcutaneous tissue, PLLA microparticles create a controlled, low-grade inflammatory response that stimulates fibroblasts to produce type I and type III collagen.

How Sculptra treatment works

Sculptra is reconstituted from powder form with sterile water (and sometimes lidocaine) before injection. The reconstituted product has a watery consistency, very different from the gel-like texture of HA fillers. It is injected in small aliquots across the treatment area using a specific fanning or cross-hatching technique.

Treatment typically requires a series of two to three sessions, spaced four to six weeks apart. This graduated approach allows the practitioner to assess the collagen response and adjust the treatment plan accordingly. It follows the principle of “treat, wait, assess”, injecting conservatively. This allows collagen production to develop, and adding more only as needed.

What Sculptra treats best

• Generalised facial volume loss: Sculptra excels at restoring diffuse volume depletion, the overall hollowing and thinning that occurs with ageing, creating a gaunt or drawn appearance.
• Temple hollowing: The temporal fossa is one of the most responsive areas to Sculptra, with excellent collagen stimulation and natural-looking volume restoration.
• Cheek and midface deflation: Gradual volume restoration in the cheeks and midface without the “pillow face” effect that can occur with HA filler overuse.
• Jawline and chin: Providing structural collagen support along the lower face.
• Body applications: Increasingly used for buttock enhancement and areas of skin laxity on the body.

Results and Duration

Visible improvement begins at approximately six to eight weeks after the first session, with progressive enhancement over three to six months. Full results are typically apparent three months after the final session. Results can last two years or longer, significantly exceeding most HA fillers.

Radiesse: Calcium hydroxylapatite (CaHA)

Radiesse contains calcium hydroxylapatite (CaHA) microspheres suspended in a carboxymethylcellulose gel carrier. CaHA is a mineral compound naturally found in bone, making it highly biocompatible. Like Sculptra, it stimulates neocollagenesis, but its mechanism and clinical properties differ in important ways.

How Radiesse works

Radiesse has a dual mechanism of action. The gel carrier provides immediate volume and structural support, giving an instant visible result similar to HA fillers. Meanwhile, the CaHA microspheres stimulate fibroblast activity and new collagen formation over the following months. As the gel carrier is absorbed (over approximately three months), it is progressively replaced by newly produced collagen around the CaHA microspheres, which themselves are eventually metabolised into calcium and phosphate ions.

More recently, Radiesse has been used in a diluted, hyperdiluted form for skin quality improvement rather than pure volumisation. When diluted and injected superficially across larger areas, it acts primarily as a biostimulator, improving skin thickness, elasticity, and overall quality without adding significant volume.

What Radiesse treats best

• Cheek augmentation: The immediate volumising effect combined with long-term collagen stimulation makes it well-suited for cheek enhancement.
• Jawline definition: Its firm consistency provides excellent structural support along the mandible.
• Nasolabial folds and marionette lines: Deep fold correction with lasting results.
• Hand rejuvenation: Radiesse holds specific approval for hand volume restoration, camouflaging visible tendons and veins.
• Skin quality (hyperdiluted): Neck, decolletage, arms, and areas of crepey skin respond well to hyperdiluted Radiesse.

Results and Duration

The immediate volumising effect of the gel carrier means results are visible from day one. As collagen production develops over three to six months, the quality of the result often improves. Total duration is typically 12 to 18 months, though some patients report lasting improvement beyond this timeframe.

Key considerations and safety

Biostimulatory fillers have specific considerations that differ from HA fillers:

• Not reversible: Unlike hyaluronic acid fillers, which can be dissolved with hyaluronidase, biostimulatory fillers cannot be easily reversed. If a complication or unsatisfactory result occurs, it must be managed rather than simply dissolved. This makes accurate injection technique and appropriate patient selection even more critical.
• Nodule risk: Both Sculptra and Radiesse carry a risk of nodule formation, small, palpable lumps caused by localised product accumulation or inflammatory response. Proper injection technique (correct depth, appropriate dilution, adequate massage for Sculptra) significantly reduces this risk. Nodules are generally manageable but can occasionally require treatment with intralesional steroid injections.
• Not suitable for lips or tear troughs: Biostimulatory fillers should not be used in areas requiring very precise placement, soft tissue integration, or where nodules would be problematic. The lips and tear troughs are treated exclusively with HA fillers.
• Gradual results require patience: Patients expecting immediate transformation will be disappointed. The best candidates understand and appreciate the gradual, natural-looking improvement that biostimulators provide.

Frequently asked questions

How do I choose between Sculptra and Radiesse?

The choice depends on your treatment goals, the areas being treated, and your practitioner’s experience and preference. Sculptra is often preferred for diffuse volume loss across larger areas, while Radiesse may be chosen for areas requiring some immediate structure as well as long-term stimulation. Some practitioners use both products in different facial zones within the same treatment plan. Your practitioner will recommend the most appropriate option during your consultation.

Can biostimulatory fillers be combined with HA fillers?

Yes, this combination is increasingly common and can be very effective. Biostimulatory fillers might be used for overall facial volume restoration and skin quality, while HA fillers provide precise enhancement in specific areas like lips, tear troughs, or fine lines. This combination approach leverages the strengths of each product type.

Are biostimulatory fillers suitable for younger patients?

While there is no strict age restriction, biostimulatory fillers are most commonly used in patients over 35 who are experiencing genuine collagen loss and volume depletion. Younger patients with good collagen production and minimal volume loss may achieve their goals more efficiently with HA fillers or skin quality treatments. However, individual assessment is more important than age alone.

How many treatments will I need?

Sculptra typically requires two to three sessions, spaced four to six weeks apart. Radiesse may achieve results in one to two sessions, depending on the treatment area and goals. Maintenance treatments are usually needed annually or biannually to sustain results, though many patients find they need less product at maintenance sessions as residual collagen from previous treatments persists. Book a consultation with a clinical team to discuss which biostimulatory approach is right for you.

This article is for informational purposes only and does not constitute medical advice. Biostimulatory fillers are medical treatments with potential risks that should be discussed thoroughly with a qualified practitioner before proceeding.