Dermal Fillers — Facial Anatomy and Safety
Where hyaluronic acid fillers are placed in the face, which structures must be avoided — and why anatomical knowledge matters more than the choice of product. A factual introduction.
Hyaluronic acid dermal fillers: anatomy, mechanism of action and safety principles
Hyaluronic acid fillers are the most widely used aesthetic procedure worldwide — and at the same time one of the most anatomically demanding. This in-depth page explains how hyaluronic acid works, which anatomical structures are relevant during treatment, where the safety risks lie and which legal framework applies in 2025.
Content of this page
- What hyaluronic acid is — chemistry and pharmacology
- Facial vascular anatomy — where safety begins
- Mechanism of action and material properties
- The six safety axes of a physician-led filler treatment
- BGH I ZR 170/24 — what changed legally in 2025
- Evidence and studies
- What dermal fillers cannot do
- Frequently asked questions
Chemistry, pharmacology and filler classification
Hyaluronic acid (HA) is an endogenous polysaccharide — a linear molecule of alternating units of N-acetylglucosamine and glucuronic acid. In the human body it is found in skin, cartilage, connective tissue and in the synovial fluid of the joints. About half of the body’s own hyaluronic acid is located in the skin, where it is responsible for hydration, volume and structural maintenance.
As an injectable filler, hyaluronic acid is cross-linked — the linear molecules are chemically joined into a 3D network. The degree of this cross-linking determines the physical properties of the material and thus its field of application:
| Property | Meaning |
|---|---|
| G-prime (elastic modulus) | A measure of the firmness of the material — high G-prime for structural support (cheekbone, jawline), low G-prime for soft volume placement (lip, tear trough) |
| Degree of cross-linking | Higher cross-linked = longer duration, firmer material; lower cross-linked = softer to model, shorter duration |
| Concentration | Typically 15–25 mg/ml — higher concentration for structural applications |
| Particle size | Microparticles in firm fillers, mono-/bi-phasic depending on the material |
| Lidocaine admixture | Most modern fillers contain a local anaesthetic (0.3% lidocaine) to improve comfort |
Filler danger zones: where the critical arteries run
The safety of a filler treatment begins with anatomy. Most complications are a direct consequence of intravascular injection — filler material enters a blood vessel and leads either to local vascular occlusion or to retrograde embolisation into more distant regions. The central vessels of every aesthetic filler treatment are:
| Vessel | Supply area · risk region |
|---|---|
| Facial artery | Runs from the mandibular border to the medial canthus — supplies cheek, nasolabial region, lip. Main vessel of mid-face treatment. |
| Angular artery | Terminal branch of the facial artery, running medial to the nasolabial fold — central risk in mid-face and tear-trough treatment. |
| Superior/inferior labial artery | Supplies upper and lower lip — the relevant vessel in lip treatment. Runs submucosally between mucosa and lip muscle. |
| Dorsal nasal artery | Terminal branch of the ophthalmic artery — supplies the nasal dorsum. In liquid rhinoplasty, retrograde embolisation carries a risk extending to the retina (blindness). |
| Supratrochlear and supraorbital artery | Forehead region — important in forehead filler and glabella application. |
| Mental artery | Emerges from the mental foramen — relevant in chin and jawline treatment. Accompanied by the mental nerve. |
| Ophthalmic artery | Internal supply of the eye — retrograde embolisation possible via anastomoses to the named facial vessels. |
How hyaluronic acid filler works in the tissue
Hyaluronic acid filler works through two combined mechanisms:
- Direct volume placement — the material cushions the tissue immediately; the mechanical augmentation produces the visible volume correction
- Water binding — hyaluronic acid binds up to 1,000 times its own weight in water. This hydration explains the “glow” effect and the sustained volume effect beyond the injected material itself
The effect is predominantly visible immediately. The final result stabilises after 7–14 days, once the initial treatment swelling has subsided and the material has fully developed its water binding. The duration depends strongly on the treatment region:
| Region | Typical duration |
|---|---|
| Lip (high muscular activity) | 6–12 months |
| Nasolabial fold | 9–14 months |
| Marionette lines | 9–14 months |
| Cheek (mid-face) | 12–18 months |
| Jawline, chin | 12–18 months |
| Earlobe | 12–18 months |
Hyaluronic acid is broken down by the body’s own enzymes (hyaluronidase) into water and CO₂. Permanent fillers are not used in Practice Ackermann — because of increased complication rates and non-reversible late reactions.
What makes a dermal filler treatment safe
An anaesthesiologist’s profile as the safety foundation
In Practice Ackermann, filler treatment is shaped by six safety axes — based on anaesthesiological routine and aesthetic experience:
- Anatomy-centred indication — no bolus without vascular mapping of the region
- Blunt microcannulas for bolus placement — reduce the risk of direct vascular puncture compared with sharp needles
- Aspiration test before every injection — standard in vessel-adjacent regions
- Hyaluronidase as an immediate antidote — kept on hand for HA-based fillers, deployable within minutes
- Anaesthesiological emergency routine — vasovagal reactions, immediate allergic reactions, local-anaesthetic reactions are standard training
- Immediate recognition of visual symptoms — pain, livid discolouration, visual disturbances as documented warning signs are established in the practice team
This safety component is not an additional marketing claim but part of the medical treatment reality. At every filler session — from the simple lip treatment to mid-face restoration — the same safety protocol is applied.
German case law (BGH I ZR 170/24): what changed for filler patients
On 10 April 2025 the German Federal Court of Justice ruled (case I ZR 170/24, Aesthetify GmbH) that hyaluronic acid treatment of the nose is to be assessed as a plastic-surgical procedure within the meaning of § 11 (1) no. 5 of the German Therapeutic Products Advertising Act (HWG). The ruling has concrete consequences for a responsible practice policy:
| Aspect | Meaning |
|---|---|
| Liquid rhinoplasty (hyaluronic acid nose correction) | Not offered in Practice Ackermann — because of the documented vascular risk (dorsal nasal artery with anastomosis to the ophthalmic artery) and the court’s assessment as an invasive plastic-surgical procedure |
| Before/after images in filler advertising | Not permitted on the website — advertising ban for such images in “surgical plastic procedures” under § 11 (1) no. 5 HWG |
| Patients with complications after liquid rhinoplasty | The practice offers second-opinion consultations, including for external patients with nose-correction complications — specialist, factual, solution-oriented |
| Extended duty to inform | Extended duty to inform for invasive aesthetic procedures — see medical professional code |
The court ruling is an important signal: aesthetic hyaluronic acid treatments are medical services with an anatomical risk profile. The promotional staging as “minimally invasive beautification without surgery” has legal and medical limits — and these limits are deliberately observed in Practice Ackermann.
Trust through clarity. The anti-liquid-rhinoplasty position is a deliberate decision based on medical responsibility — not on marketing differentiation.
What the scientific literature shows
Hyaluronic acid filler is one of the best-studied aesthetic procedures. Several systematic reviews document efficacy, safety profile and typical complication patterns:
What dermal fillers cannot do
Six honest limits of filler treatment
- No substitute for plastic-surgical procedures. With pronounced skin laxity, major volume loss or skeletal asymmetries, surgical procedures (facelift, genioplasty, mid-face lift) are anatomically more appropriate. We advise honestly.
- No permanent solution. Hyaluronic acid is broken down by the body. Duration is 6–18 months depending on the region. Permanent fillers are not used — because of increased complication rates and non-reversible late reactions.
- No standard schemes. “Liquid face lifts” with fixed point plans without individual anatomy analysis often lead to disproportionate results. Practice Ackermann works deliberately with individual medical planning.
- No isolated wrinkle filling. Anyone wanting a pure “wrinkle-in-the-mirror” correction is directed to the anatomical causes — often treatment of a different region (mid-face, DAO) is more sensible than the direct wrinkle injection.
- No liquid rhinoplasty. Hyaluronic acid nose correction is not offered in the practice — because of vascular risk and the court’s assessment as an invasive procedure (see above).
- Not a cosmetically performable treatment. The intravascular application of hyaluronic acid in a vessel-adjacent region is a medical service. No cosmetic institute, no hairdresser, no non-medical practitioner may inject filler — the law on healing professions is unambiguous.
Frequently asked questions about dermal fillers
What distinguishes medical from cosmetic filler treatment?
Filler injection is legally a medical procedure — no cosmetic studio, no non-medical practitioner and no hairdresser may offer it. The difference lies not in the material but in anatomical knowledge, complication competence and emergency routine. With the rare but serious complications (vascular occlusion), immediate recognition often decides the outcome.
Is hyaluronic acid filler safe?
With correct indication and medical execution the safety profile is very good — hyaluronic acid is endogenous, well tolerated and reversible with hyaluronidase. The rare complications (vascular occlusion, granuloma, late infection) are documented and can be minimised through standardised safety protocols.
How long does hyaluronic acid filler last?
Depending on the region, 6–18 months. Lip filler 6–12 months (high muscular activity), mid-face and lower-face filler 12–18 months (lower tissue metabolism). Duration depends on the material (degree of cross-linking), the treatment region and individual factors.
Can I reverse hyaluronic acid filler?
Yes — with hyaluronidase, an enzyme that breaks down hyaluronic acid. With a suboptimal result the material can be dissolved within 24–48 hours. This reversibility is one of the central safety aspects of hyaluronic acid fillers. More: Hyaluronidase treatment.
Which filler brands do you use?
We use exclusively approved hyaluronic acid fillers from reputable manufacturers with an established safety and efficacy profile. Brand names are not advertised on the website — this does not fit the factual tone of the practice. In a personal consultation we clarify all details transparently.
Why don’t you offer hyaluronic acid nose correction?
For two reasons: first, the nasal region is particularly high-risk due to its vascular supply (dorsal nasal artery with anastomosis to the ophthalmic artery) — cases of vision loss are documented. Second, the Federal Court of Justice ruled in April 2025 (I ZR 170/24) that hyaluronic acid nose treatment is to be assessed as a plastic-surgical procedure. Out of medical and legal responsibility it is not offered in Practice Ackermann.
What is the difference between hyaluronic acid and hydroxyapatite?
Hyaluronic acid is reversible (dissolvable with hyaluronidase) and works for 6–18 months. Hydroxyapatite (CaHA) is not directly reversible, additionally stimulates collagen formation, and works for 18–24 months. Hybrid fillers (HA + CaHA) combine both properties. More: Hybrid-Biostimulator.
What happens if I have pain or unusual symptoms after filler treatment?
Mild pain, a feeling of tension and small haematomas in the first 24–48 hours are normal. With severe pain disproportionate to the injection, pale or livid skin, visual disturbances or pronounced swelling, contact the treating practice immediately or, with acute symptoms, the emergency department. More: Recognising filler complications
Individual filler treatments in detail
Cheek augmentation
Mid-face anchor with 5-subzone anatomy · anatomical consequence of mid-face atrophy
Nasolabial fold
Targeted softening of the nasolabial fold — addressing the anatomical cause
Lips in harmony
Lip modelling with 5-zone anatomy
Jawline definition
Sex-specific contouring of the lower jaw
Chin augmentation
Proportional anchor of the lower facial third
Marionette lines (filler)
Three-mechanism treatment with botulinum-toxin–filler combination
Pleats (perioral)
Perioral crinkle-line treatment
Hybrid biostimulator
HA + CaHA material for structural anchor treatments
Dissolving hyaluronic acid (hyaluronidase)
Reversibility anchor for the entire filler segment · second-opinion consultation after treatments in other practices
Earlobe correction
Volume restoration of the earlobe
Dr. med. Thomas Ackermann
Specialist in Anaesthesiology, private practice Harmonie der Ästhetik Herzogenaurach. An anaesthesiological profile as the safety foundation of aesthetic filler treatment — complication competence from clinical everyday practice, combined with aesthetic experience in the practice.
This page provides an initial overview and does not replace medical advice. What a treatment specifically means for you — which method, which dosage, which expectation is sensible — belongs in a personal consultation at the practice, with an examination and time. Every aesthetic-medical procedure carries individual risks that require personal clarification (§ 630e German Civil Code).
Skin Analysis
Wrinkles & Muscle Relaxants
Bio-Regeneration (Skin Quality)
HIFU Lifting
Primary Care Support
Tension & Pain
Hair Health & Hair Loss
Skin Diseases
Drip Spa & Infusion Medicine
