No. Unlike hyaluronic acid, biostimulators cannot be dissolved. That is exactly why treatment is deliberately conservative and staged over several sessions with review in between.
Overview
Collagen grown, not volume injected
Where the loss is structural, the answer is structural collagen — grown, not injected.
Two families do the structural work, and they do not work the same way. Poly-L-lactic acid provokes a deliberate, low-grade, localised foreign-body response: immune cells wall off the microparticles, and in doing so your own fibroblasts build a collagen capsule around them. Human biopsy work shows exactly that architecture — macrophages and myofibroblasts, type III collagen immediately against the particles and type I at the periphery. The particles are slowly metabolised; the capsule remains. Calcium hydroxylapatite works differently: its microspheres activate fibroblasts by direct contact, while the gel they are suspended in gives an immediate correction that resorbs over the following months. Diluting it heavily turns a volumiser into a biostimulator by spreading the microspheres and reducing the carrier effect.
Neither behaves like a hyaluronic acid filler, and one difference matters more than all the others: neither can be dissolved. There is no antidote, no equivalent of hyaluronidase. That is the real trade-off behind the phrase “more natural”, and it is the reason these are injected conservatively, under-corrected on purpose, and reviewed before more is added.
In scar work, calcium hydroxylapatite has a specific and useful role: placed beneath a scar that has just been released by subcision, it supports the floor while new collagen forms in the space that was opened.
At a glance
- Treatment time30–45 minutes
- AnaestheticTopical anaesthetic; lidocaine is often in the product
- DowntimeSwelling and possible bruising for 2–5 days
- Sessions1–3, spaced 4–8 weeks apart
- ResultsBuild over 3–6 months; last 2 years or more
- Combines withSubcision, energy devices, hyaluronic acid
How it works
A scaffold, then a response
The response to poly-L-lactic acid is, in plain terms, a controlled and deliberately subclinical foreign-body reaction. That sounds alarming and is not: measured against baseline, the degree of inflammation in human tissue studies was mild or absent at three, six and twelve months. It is simply the accurate description of the mechanism, and it explains both why the result is gradual and why it cannot be reversed. Particles have been recovered from tissue twenty-eight months after injection.
Because the effect accumulates and cannot be dissolved, treatment is deliberately conservative. Under-correcting and reviewing at eight weeks is the correct approach; chasing an immediate result with a biostimulator is how over-correction appears six months later, when there is nothing to be done but wait.
Technique accounts for most of the complication rate. Poly-L-lactic acid is reconstituted well in advance — longer hydration produces more collagen and fewer particles clumping — injected deeply rather than superficially, kept away from thin-skinned areas, and followed by a massage protocol that is demonstrated to you before you leave. Papules or nodules occurred in about one patient in six in the registration trial, and in roughly 28 per cent of patients across all treated facial areas in the larger five-year study that followed it — a rate that exceeded the threshold set in advance, and which rises with the volume injected. Most of what is reported in practice traces back to placement that was too shallow or too concentrated.
Indications
Suited to
- Generalised loss of facial support and structure
- Temples, mid-face and jawline where volume has receded
- Skin thinning across the lower face and neck
- Supporting a scar floor released by subcision
- Décolletage, upper arms and knees
- Patients who prefer a gradual, unannounced change
- Thin-skinned, highly mobile areas — around the eyes and in the lips, where nodules are far likelier
- A patient who wants a result this month, or wants the option of reversing it
- Active autoimmune or granulomatous disease
- A tendency to keloid or hypertrophic scarring
- Active infection anywhere in the treatment field
- Pregnancy and breastfeeding
In the clinic
Step by step
Planning
The pattern of loss is assessed with the face at rest and in movement, and a conservative dose is planned across one to three sessions.
Injection
Product is placed in the relevant plane with a needle or cannula. Most preparations contain lidocaine, which makes the procedure comfortable.
Massage
Where the product requires post-treatment massage, the technique and schedule are shown to you before you leave.
Review at eight weeks
Assessment of the response and a decision on whether a further session is warranted.
The endpoint at three to six months
This is where the treatment is judged — and where its longevity begins.
Recovery
Downtime, honestly
The same day
Swelling, and with calcium hydroxylapatite an immediate fullness from the carrier gel that is not the result — it is temporary and will go. Poly-L-lactic acid gives you the volume of the fluid it is suspended in, and nothing else.
Days one to five
Swelling and bruising settle. Where massage is part of the protocol it starts now and is not optional.
Weeks two to eight
The apparent correction disappears as the carrier resorbs. Patients who were not warned about this are the ones who call. Collagen is being laid down in the background.
Months two to six
The actual result arrives, gradually enough that most people around you will not identify what changed. Review at eight weeks, and add only then if it is genuinely needed.
Beyond
Effect from poly-L-lactic acid was demonstrated to thirteen months in the registration trial and followed to twenty-five. For diluted calcium hydroxylapatite, type I collagen was still significantly raised at seven months in the key study, with type III already declining.
Risks
What can go wrong
Expected
Swelling, bruising and tenderness for a few days. A period in the second month where it looks as though nothing has happened.
Uncommon
Papules and nodules — about one patient in six in the registration trial for poly-L-lactic acid, and roughly 28 per cent across treated facial areas in the five-year follow-up study, typically traceable to superficial or over-concentrated placement. Visible or palpable lumps in mobile areas. Asymmetry from uneven collagen response.
Rare but serious
True inflammatory granuloma, reported at roughly one patient in a thousand in the largest long-term study, and sometimes appearing long after treatment. Vascular occlusion, as with any filler — and here it matters much more, because neither product can be dissolved. There is a published case of blindness following calcium hydroxylapatite.
This is the paragraph a biostimulator page usually leaves out, and it is the one that should change how the treatment is given: conservative volumes, correct plane, cannula where anatomy allows, and no attempt to achieve in one session what should take three.
Evidence
What the evidence shows
Strong for PLLA, thin for skin-quality claimsPoly-L-lactic acid has what almost nothing else on this site has: a randomised, evaluator-blinded, controlled registration trial, with 233 subjects, a primary endpoint at thirteen months and an extension to twenty-five. Its mechanism has been characterised in human biopsy tissue rather than inferred. When we say it builds collagen, that is a supported statement.
The skin-quality case for heavily diluted calcium hydroxylapatite is weaker and should be labelled as such. The study everyone cites — and it is genuinely interesting, with biopsies showing significantly increased type I and type III collagen, elastin and new vessels at four and seven months — is a twenty-subject pilot with no control arm. The consensus documents built on top of it are expert opinion, not evidence.
Two words we avoid as a result. “Tightening”, because it implies something comparable to an energy device or to surgery that this data does not support; firmness and skin quality are the honest terms. And “permanent”, because the demonstrated effect runs to one or two years, not indefinitely.
If you are travelling
A session is thirty to forty-five minutes and you can fly the following day. Where a massage protocol applies, it has to be done properly for several days afterwards, so it is worth arriving with a clear few evenings rather than a schedule.
The course is usually two or three sessions four to eight weeks apart. That is the main planning constraint, and the review at eight weeks can be done on photographs.
One request we make of international patients specifically: do not have more added elsewhere between sessions. These products accumulate, cannot be removed, and the commonest cause of an over-filled face is two clinicians each adding a conservative amount.
Questions
Good to know
If your question is not here, ask it in the enquiry form — Dr. Henningsen answers these personally.
Ask a question- Is this reversible?
- How long does it last?
Often two years or more, because what remains is collagen you produced rather than a product that degrades.
- Can lumps or nodules occur?
Rarely, and the risk is minimised by correct dilution, correct plane, appropriate volumes and post-treatment massage where the product requires it. This is a treatment where the operator's technique matters a great deal.
- Is it used in scar treatment?
Yes. Calcium hydroxylapatite in particular is useful beneath a scar released by subcision, supporting the floor while new collagen forms. It is not appropriate in the same session as tumescent anaesthesia, which would simply wash it away.
Consultation
Ready to talk about your skin?
Consultations with Dr. Henningsen are arranged individually. Tell us what you would like to change and we will come back to you with the options, the honest downtime and the realistic result.