Dermal fillers

This article covers what filler materials can change, how those changes are measured, and where the limits of the evidence lie. Hyaluronic acid filler is at its centre. How it differs from other materials, the nose as a region, longevity, reversibility and vascular complications are considered together. The aim is not to recommend a product or a procedure but to explain what the statements made about fillers actually mean.

What is a filler?

Filler is the shared name for different substances injected in order to add volume to tissue or to reduce particular contour irregularities.¹ It does not describe a single material, a single treatment area, or a result that lasts the same length of time.¹ For that reason the information that "a filler was used" is not enough on its own to explain which substance was used, or what options exist if a problem arises.

Are hyaluronic acid and the other filler materials the same thing?

Hyaluronic acid (HA) is one of the substances used in filler products. The United States Food and Drug Administration (FDA) describes HA, along with calcium hydroxylapatite and poly-L-lactic acid, among the absorbable materials, and polymethylmethacrylate microspheres among the non-absorbable materials.¹ It cannot be said that every filler other than HA is permanent.¹

The effects of poly-L-lactic acid are reported to become increasingly apparent over a period of several weeks and may last up to 2 years, while the duration given for hyaluronic acid is approximately 6 to 12 months.¹ These are general institutional figures, not a schedule given to an individual. When the words "temporary", "semi-permanent" or "permanent" are read, which substance and which outcome is being spoken of has to be distinguished.

The word "filler" covers different substances; the possibility of dissolving that is described for hyaluronic acid is not generalised to every ready-made filler.² Poly-L-lactic acid, calcium hydroxylapatite and polymethylmethacrylate are stated not to be dissolvable with hyaluronidase.² That difference concerns not only how long the effect lasts but also which corrections may be possible in the face of an unwanted result.

How does it differ from botulinum toxin and fat injection?

Botulinum toxin does not add volume to tissue; it reduces muscle activity.³ Filler adds volume. The two address different aims and do not stand in for one another.³ The evidence and the limits concerning reduced muscle movement are taken up separately in the botulinum toxin article.

Hyaluronic acid filler is a ready-made substance; a fat graft requires tissue to be taken from the person's own body.^1,4 Fat injection concerns the transfer of the person's own tissue in place of a ready-made substance. Vascular complications have been reported with both approaches.⁵ The difference between using a person's own tissue and using a ready-made substance does not mean that either one carries no vascular risk.⁵

What changes are expected, and what are not?

How are volume loss and tissue descent distinguished?

Filler studies have assessed different features, such as lip fullness and the prominence of the nasolabial fold running from the side of the nose to the corner of the mouth.^6,7 An increase in fullness measured in a lip study does not show that the same result is achieved in every region of the face. In the same way, a reduction in the score of a fold is not a measurement that every sign of ageing in that face has improved.

Adding volume and repositioning tissues surgically are not the same aim. In reading filler data, instead of a broad description such as "a face-lift effect", what matters is which region and which change the study measured. The effectiveness data below concern lip fullness and fold severity; they are not a test of equivalence with surgery.^6,7

Naming the region alone is not enough in an assessment. Knowing the previous procedures and the substance used matters; the methods that can be chosen to reduce a filler differ according to the substance.² The FDA also asks that active infection or inflammation, bleeding disorders and a history of severe allergy be disclosed before assessment.⁸ This information indicates that a wish about appearance is not on its own a decision to have a procedure.

The expectation also has to be concrete. Describing the feature that is to change, rather than "looking younger", makes it easier to compare the result being described with the result the research measured. That a study shows a benefit does not mean that everyone with a similar appearance should have the procedure. Not having the procedure is also part of the assessment.

Does a nose filler take the place of surgery?

Nose filler is considered as a way of camouflaging particular contour irregularities by adding volume.⁴ In the review by Hall and Kontis it is stated that this aim has to be separated from people who need a reduction rhinoplasty; placing filler adds volume to the nose.⁴ For that reason seeing a change in profile does not mean the nose has been made smaller.⁴

Nose filler and rhinoplasty should not be read as equivalent options under the same heading. This page assesses the contour aim of filler and its vascular risk. Structural corrections made surgically are the subject of a separate article. The duration of effect or the success rate from the lip study is not used for the nose.

Among the risks reported in the nose review are skin necrosis (death of tissue) and irreversible vision loss due to vascular occlusion.⁴ That a small change in appearance is the aim does not mean that any complication will also necessarily be small. At the same time, the existence of these risks and the probability of their occurring in one person are different questions; the evidence on regions is given below with that distinction.

What does the evidence on effectiveness show?

How is the effect measured in the studies?

In the review by Czumbel and colleagues on lip filler, 32 studies were assessed qualitatively and 10 studies were taken into the quantitative analysis.⁶ A response was defined as an improvement of at least 1 grade from baseline on a lip fullness scale.⁶ This threshold does not mean by what percentage a person's appearance improved, or whether they were satisfied with the procedure.

Time of assessment	Pooled proportion of responders	95 per cent confidence interval	Number of studies
2 months	91 per cent	85-96 per cent	5
3 months	71 per cent	55-87 per cent	8
6 months	74 per cent	66-82 per cent	5
12 months	46 per cent	28-65 per cent	4

The values in the table are results from the same review.⁶ Variation between studies is high; at the time points the I² values were reported as 82.7, 97.91, 66.88 and 93.21 per cent respectively.⁶ That measure serves to assess how similar the study results are to one another; it is not the probability of failure in one person.

In untreated groups the response at 2 months was reported in 3 studies as 21 per cent, 95 per cent confidence interval 6-40 per cent.⁶ That information should not be used to read all the time points as a single treated-versus-untreated experiment. The sets of studies in the table differ; the rise in the proportion from 3 months to 6 months does not mean that the effect strengthened again in the same people.⁶

How long does the visible effect last?

For the nasolabial fold, the review by Stefura and colleagues used another measure, the Wrinkle Severity Rating Scale (WSRS).⁷ A lower score indicates a less prominent fold.⁷ The values below belong only to the combined HA column; they have not been merged with the results for other materials.⁷

Time	Mean WSRS	95 per cent confidence interval	Number of studies
Baseline	3.26	3.21-3.30	10
1 week	2.91	2.82-2.99	2
2 weeks	1.91	1.83-2.00	4
1 month	2.04	1.98-2.10	4
2 months	1.83	1.79-1.87	7
3 months	2.13	2.03-2.22	3
4 months	1.97	1.93-2.01	8
5 months	2.00	1.72-2.28	1
6 months	2.08	2.04-2.11	12
9 months	2.29	2.20-2.38	2
12 months	2.46	2.38-2.54	3

These findings show that improvement in the measured fold severity was reported.⁷ Each row is not, however, the sequential follow-up of the same group of patients. Combining the post-baseline scores from different studies does not produce a result curve that can be applied to everyone. Nor can the response percentage in the lip table be added to the mean score here, or used in its place.

The question "how long does it last?" therefore first requires knowing which outcome was followed. Finding an improvement on a scale at a given time does not say how much of the substance remained on that day. A person's wanting a repeat procedure is not the measurement in these tables either. No interval for repeat treatment suitable for every facial region, and no definite end date for an individual, can be derived from these studies.^6,7

What does finding filler on imaging mean?

Master and colleagues assessed mid-face MRI examinations of 33 people who reported that at least 2 years had passed since their last HA injection. Of these, 24 were without symptoms and 9 were assessed because of concern about oedema; the reported time since the last procedure was 2 to 15 years, and a signal consistent with HA was found in all of them.⁹

This study is not a review of 33 pieces of research, nor a follow-up in which everyone was observed for 15 years. It contains the imaging of selected people; in 17 of them the product is not known, and the information about previous procedures rests on patient history.⁹ These conditions limit generalising the finding to everyone who has had filler.

An MRI finding is not a measurement that the visible effect has been maintained for the same length of time.⁹ When appearance on a scale, detection on imaging and the request for a repeat procedure are kept separate, research reporting different durations does not in itself constitute a contradiction. The question of one piece of research is "does the improvement on a fullness scale persist", and of another "is there a signal consistent with HA in the tissue".^6,9

How are authorisation and product suitability assessed in Türkiye?

Are a certificate and a facility's authorisation the same thing?

How health services for aesthetic and cosmetic purposes are to be provided in private outpatient diagnosis and treatment facilities is governed by the Regulation on Private Health Facilities Providing Outpatient Diagnosis and Treatment, dated 19 April 2025.¹⁰

The provision in force requires three conditions together. Health services for aesthetic or cosmetic purposes may be provided within a medical centre, a polyclinic or a doctor's practice; within the competences physicians have acquired through their training curriculum or through a certificate; within the medical procedures permitted at the facility where they work; and provided that the physical space and minimum medical equipment defined for a polyclinic room are in place.¹⁰

The certificate referred to in the regulation is one registered under Ministry legislation.¹⁰ Filler appears as a heading in both the theoretical and the practical training in the Ministry's Standard for the Certified Training Programme in Aesthetic and Cosmetic Applications, dated 3 September 2025.¹¹ Its being in the same programme as botulinum toxin does not mean that every application requires the same competence or the same conditions.

The physician's competence and the facility's authorisation are separate things and both are required.¹⁰ A diploma alone, or any course certificate alone, does not show that all of these conditions are met. Nor is a training centre's authorisation to provide training the same thing as a physician's authorisation to carry out the procedure.^10,11

This provision covers private outpatient diagnosis and treatment facilities. A complete list of authorisation by profession and title, for every type of institution, cannot be derived from this text.¹⁰

What can be asked about the product?

Where the product stands in the legislation is a separate question from a person's authorisation to carry out the procedure. The Communiqué of the Turkish Medicines and Medical Devices Agency dated 14 March 2024 concerns the non-medical-purpose product groups listed in Annex XVI of the Medical Device Regulation. Article 5(4) expressly covers facial, dermal and mucous-membrane filler substances used by subcutaneous, submucous or intradermal injection or by another route of application.¹²

The Ministry of Health's Product Tracking System (ÜTS) is a system for the registration and traceability of medical devices and cosmetic products.¹³ A product's registration information does not take the place of a physician's competence or a facility's authorisation. The traceability of a product and the benefit and risk expected in a particular person are also separate assessments.

Among the questions that make a product assessment concrete are what the product used is and to which area each product is to be applied.³ The Ministry states that, through the ÜTS mobile application, both members of the public and health personnel can query information about the medical device or cosmetic product to be used.¹³ Saying only the product family, or the word "filler", does not answer all of these questions.

FDA approval in the United States relates to particular areas of use; it cannot be generalised to every region, nor to the conditions for authorisation in Türkiye.^3,10 Without understanding the physician's competence, the services permitted at the facility and the suitability of the product together, the word "approved" alone does not constitute a sufficient explanation.

What are the risks and unwanted effects?

Early reactions and problems that appear late

Swelling, bruising, redness, pain and tenderness are among the reactions reported after injection. The FDA states that many of these can subside within days or weeks.³ That general information does not mean that every complaint which begins later, or which steadily increases, is to be accepted as ordinary.

Problems such as nodules (a lump that can be felt), inflammation, infection and displacement of the material have also been reported.² The type of problem and the substance used can affect the assessment and the correction options.² It should not be assumed that early swelling and a late nodule occur at the same frequency and follow the same course.

For some of these risks there is numerical research below; a single total risk percentage covering every material and every region is not given. A problem that is not described with a number is not counted as less important. That different studies record different events makes direct comparison of the rates difficult.

Vascular occlusion and conditions affecting vision

Filler that passes into a blood vessel can disrupt blood flow; serious consequences such as tissue loss, vision loss and stroke have been reported.⁸ The FDA states that the probability of these events is low, and that when they do occur the consequences can be serious and permanent.⁸ The frequency with which an event occurs and the probability of recovery after an event has occurred are given separately below.

The study by Alam and colleagues rests on the retrospective reports of 370 dermatologists.¹⁴ The denominator is not the number of people but the equivalent of 1 mL of filler injected. The volume here indicates only the unit of calculation used in the research; it is not a recommendation about how much to use.¹⁴

Material	Vascular occlusion with needle / volume equivalent	Vascular occlusion with cannula / volume equivalent
All materials	176/1128192	13/531466
Hyaluronic acid	162/927841	12/420281
Poly-L-lactic acid	4/82593	0/39550
Polymethylmethacrylate	0/24034	1/14647
Calcium hydroxylapatite	10/64399	0/40118

The table shows the material groups of the study.¹⁴ The row for all materials is not arrived at by adding the rows beneath it. For HA, approximately 1 event per 5727 volume equivalents and 1 per 35023 volume equivalents were reported.¹⁴ A retrospective observational association does not show that the cannula protects under all conditions; nor does a group in which zero events were reported mean zero risk.

The review by Doyon and colleagues, on the other hand, examined not the number of procedures but 365 new cases in which vision loss had developed.¹⁵ In the 318 cases with a visual outcome reported, complete recovery was 6.0 per cent, partial recovery 25.8 per cent and no recovery 68.2 per cent.¹⁵ Different filler materials are present in this review; the figures are not the outcome for everyone using HA.¹⁵

These three percentages are the distribution of cases in which vision loss had already developed and an outcome was reported. They do not give the probability of a person who has filler losing their vision, and they cannot be added to Alam's volume denominator. One describes how often occlusion was reported, the other what followed in selected complication cases.^14,15

Are the nose, the glabella and other regions at the same risk?

The consensus by Goodman and colleagues divides regions into relative risk classes with respect to vision loss.⁵ This classification is not a frequency table measuring how many events were seen in how many procedures in each region.⁵

Relative class in the consensus	Regions
Very high	Glabella (between the eyebrows), nose, forehead
High	Temples, nasolabial folds, tear troughs, peri-orbital region, medial cheek
Moderate	Lips, perioral region, anterior cheek
Low	Jawline, marionette region, lateral cheek, sub-malar region, preauricular region, chin

The four classes in the table are taken from the same consensus.⁵ The medial cheek is defined as lying between the mid-pupillary line and the side of the nose, the anterior cheek between the mid-pupillary line and a vertical line through the lateral canthus, and the lateral cheek lateral to that line.⁵ The "low" class does not mean a safe or risk-free region.

The anatomical basis for this distinction is the connections between the facial vessels and the circulation of the eye; material entering a vessel can affect the ocular circulation through these connections.⁵ The separate emphasis on the nose and the glabella rests on that framework. A personal risk percentage cannot be derived from the distribution of case reports across regions.

When should a doctor be contacted?

When unusual pain, a white, grey or blue change of colour in the skin, or a change in vision occurs during the procedure or shortly afterwards, immediate medical assessment is needed.⁸ Sudden difficulty speaking, weakness in the face or limbs and other signs suggesting a stroke also require urgent assessment.⁸

Suspected vision loss is a vascular emergency; the consensus states that specialist assessment has to be reached without delay.⁵ The complaint is not expected to run the ordinary course of swelling. A lump appearing later, a discharging wound or inflammation are also different problems requiring assessment.³ Rather than counting all of these at the same level of urgency, sudden visual and circulatory signs are set apart.

What can dissolving with hyaluronidase reverse?

With hyaluronic acid fillers, hyaluronidase can be used to reduce unwanted volume.¹⁶ Hyaluronidase is an enzyme that breaks down HA; it is not a route of reversal that applies to all other substances.^2,16 A fat graft is likewise not regarded as a material that can be reversed in the same way as HA filler.⁴

The review by Borzabadi-Farahani and colleagues included 5 randomised controlled trials and a total of 53 people.¹⁶ The experiments examined the dissolution of uncomplicated HA deposits in the skin of the forearm, upper arm or back.¹⁶ That finding supports the biological effect of dissolving; it does not measure the treatment of facial vascular occlusion or vision loss in the same way.

This distinction is not a dismissal of the benefit. Evidence about reducing unwanted HA volume and evidence about undoing damage that has occurred do not answer the same question. The review's search extends to May 2022; the absence of controlled trials should be read within the limits of that search and those selection criteria.¹⁶

Are unwanted volume and a vascular complication the same problem?

Reducing excess volume in a region and the healing of tissue whose blood supply has been cut off are different outcomes. In Doyon's case review, visual improvement was reported in some people, but no significant association could be shown between the treatments examined and visual improvement.¹⁵ That this association could not be shown in observational case data is not proof that the treatments are ineffective, nor a reason to forgo urgent intervention.^5,15

There is also a possibility of an allergic reaction to the dissolving procedure itself.¹⁶ That substances other than HA cannot be dissolved with the same enzyme does not mean that all correction options are impossible either; the substance used and the problem are assessed separately.² The words "reversible" should therefore not be used as a guarantee without explaining which outcome can be changed by which method.

What is known about pregnancy and breastfeeding?

The FDA states that the safety of filler products during pregnancy and breastfeeding is not known.⁸ That statement does not mean that safe use in these periods has been shown; nor is it a rate showing that every exposure causes harm. An absence of data should not be turned into either of these two conclusions.

Data concerning pregnancy or breastfeeding for botulinum toxin do not constitute an answer for filler, which is a different substance. What the product is and its own safety information are the basis for assessment. This article does not set out a framework recommending the aesthetic use of filler during pregnancy or breastfeeding.

How should the marketing language be read?

The words permanent, reversible and natural

These words can merge different questions into a single favourable impression. When "permanent" is said, it has to be asked whether what is meant is that the substance is not absorbed or that the appearance does not change. Information about the presence of non-absorbable microspheres is not a measurement that a person's appearance will always remain the same.¹ In the same way, finding a signal on MRI does not mean that the aesthetic effect has been maintained for the same length of time.⁹

The expression "reversible" is likewise not sufficient without the substance being stated. That HA volume can be reduced, that every filler can be dissolved, and that vascular damage can be undone are not the same claim.^2,15,16 If a text skips these distinctions, the word used may carry a broader assurance than the research shows.

"A natural appearance" is not on its own a scientific outcome measure. Without stating which region was followed, on which scale and for how long, this expression should not be read as a research result. Nor does the same appearance have to be the aim for everyone; a change on a scale does not decide a matter of personal preference.

Does needle-free filler give the same assurance?

The FDA states that needle-free systems that deliver filler under pressure are not approved for filler injection and that serious harm has been reported with them.³ The absence of a needle does not mean that the substance is not delivered into the tissue, or that vascular and tissue harm has been removed.³

What is described here by "needle-free" are systems that deliver filler material into the tissue under pressure. It should not be assumed that any product applied to the surface is the same procedure. Before the naming, what is applied and by which route has to be understood. The FDA's statement also does not take the place of the texts that determine the authorisation of people and facilities in Türkiye.

How should the numbers in this article be read?

The lip table describes a particular scale response, the nasolabial table a mean fold severity, and the MRI study detection on imaging. A single duration of persistence cannot be produced from these.^6,7,9 A study's follow-up time is not a date for repeat treatment for everyone.

A confidence interval shows the uncertainty of the estimate in the research; it is not a guaranteed range of results for an individual. That the numbers of studies change over time and that the results differ from one another also have to be taken into account when the tables are read. That a mean or a response percentage exists does not show that everyone will experience that value.

The denominator of the vascular occlusion table is a volume equivalent. The denominator of the visual recovery rates is the cases in which vision loss developed and an outcome was reported.^14,15 These rates are not added together, are not converted into one another, and are not to be read as a person's total risk. The regional classification is not a measured frequency table either.⁵ What research data contribute to making a decision is understood when these distinctions are preserved.

References

1. U.S. Food and Drug Administration. FDA-Approved Dermal Fillers. fda.gov ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

2. Kroumpouzos G, Treacy P. Hyaluronidase for Dermal Filler Complications: Review of Applications and Dosage Recommendations. JMIR Dermatol. 2024;7:e50403. doi:10.2196/50403 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

3. U.S. Food and Drug Administration. Dermal Filler Do's and Don'ts for Wrinkles, Lips and More. Content current as of 7 July 2023. fda.gov ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

4. Hall SS, Kontis TC. Nonsurgical rhinoplasty. World J Otorhinolaryngol Head Neck Surg. 2023;9(3):212-219. doi:10.1002/wjo2.104 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

5. Goodman GJ, Magnusson MR, Callan P, et al. A Consensus on Minimizing the Risk of Hyaluronic Acid Embolic Visual Loss and Suggestions for Immediate Bedside Management. Aesthet Surg J. 2020;40(9):1009-1021. doi:10.1093/asj/sjz312 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰

6. Czumbel LM, Farkasdi S, Gede N, et al. Hyaluronic Acid Is an Effective Dermal Filler for Lip Augmentation: A Meta-Analysis. Front Surg. 2021;8:681028. doi:10.3389/fsurg.2021.681028 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹

7. Stefura T, Kacprzyk A, Droś J, et al. Tissue Fillers for the Nasolabial Fold Area: A Systematic Review and Meta-Analysis of Randomized Clinical Trials. Aesthetic Plast Surg. 2021;45(5):2300-2316. doi:10.1007/s00266-021-02439-5 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

8. U.S. Food and Drug Administration. Dermal Fillers (Soft Tissue Fillers). fda.gov ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

9. Master M, Azizeddin A, Master V. Hyaluronic Acid Filler Longevity in the Mid-face: A Review of 33 Magnetic Resonance Imaging Studies. Plast Reconstr Surg Glob Open. 2024;12(7):e5934. doi:10.1097/GOX.0000000000005934 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

10. Republic of Türkiye Ministry of Health. Regulation on Private Health Facilities Providing Outpatient Diagnosis and Treatment. Official Gazette, 19 April 2025, no. 32875. Articles 4(1)(j) and 6(10). saglik.gov.tr ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷

11. Republic of Türkiye Ministry of Health. Standard for the Certified Training Programme in Aesthetic and Cosmetic Applications. 3 September 2025. saglik.gov.tr ↩ ↩²

12. Turkish Medicines and Medical Devices Agency. Communiqué on the Determination of Common Specifications for the Groups of Products Without an Intended Medical Purpose Listed in Annex XVI of the Medical Device Regulation. Official Gazette, 14 March 2024, no. 32489. Article 5(4). resmigazete.gov.tr ↩

13. Republic of Türkiye Ministry of Health. The Product Tracking System has come into operation. saglik.gov.tr ↩ ↩²

14. Alam M, Kakar R, Dover JS, et al. Rates of Vascular Occlusion Associated With Using Needles vs Cannulas for Filler Injection. JAMA Dermatol. 2021;157(2):174-180. doi:10.1001/jamadermatol.2020.5102 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶

15. Doyon VC, Liu C, Fitzgerald R, et al. Update on Blindness From Filler: Review of Prognostic Factors, Management Approaches, and a Century of Published Cases. Aesthet Surg J. 2024;44(10):1091-1104. doi:10.1093/asj/sjae091 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸

16. Borzabadi-Farahani A, Mosahebi A, Zargaran D. A Scoping Review of Hyaluronidase Use in Managing the Complications of Aesthetic Interventions. Aesthetic Plast Surg. 2024;48(6):1193-1209. doi:10.1007/s00266-022-03207-9 ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷