Dermal fillers approved by the FDA are made mainly of one of four materials: hyaluronic acid, calcium hydroxylapatite, poly-L-lactic acid, or tiny polymethylmethacrylate (PMMA) beads suspended in a collagen gel, and some also contain the numbing medicine lidocaine. The material affects how long a filler lasts, whether it can be broken down if needed, and which allergies matter. Here is what each one is and what to ask before treatment.
What are dermal fillers made of?
The FDA regulates dermal fillers, which it notes are also called soft tissue fillers, facial fillers or wrinkle fillers, as medical device implants. They are approved to help create a smoother or fuller appearance in specific areas of the face and the back of the hands. The FDA groups the approved materials into two categories:
- Absorbable (temporary) materials, which the body gradually breaks down: hyaluronic acid, calcium hydroxylapatite and poly-L-lactic acid.
- Non-absorbable materials, which the body does not break down: PMMA beads.
Fillers can also be sorted by origin. Hyaluronic acid is a substance also found in skin, and calcium hydroxylapatite is a mineral found in teeth and bone. Poly-L-lactic acid and PMMA are synthetic fillers, meaning man-made polymers. Synthetic does not mean permanent: the FDA describes poly-L-lactic acid as biodegradable and PMMA as non-biodegradable.
The FDA notes that approvals are specific. Absorbable fillers are approved for uses such as moderate to severe facial wrinkles and folds and augmentation of the lips, cheeks, chin or back of the hand, depending on the product. The non-absorbable filler is approved only for nasolabial folds and cheek acne scars. Approval depends on the exact product, area and purpose, so ask which product is proposed and whether your plan is on-label or off-label.
What is hyaluronic acid filler?
The FDA describes hyaluronic acid as a type of sugar (polysaccharide) that is naturally present in body tissues such as skin and cartilage. For use as a filler, it may be chemically modified, or crosslinked, so it lasts longer in the body. The FDA notes that the hyaluronic acid in fillers can come from bacteria or from rooster combs, and that its effects last approximately 6 to 12 months.
The source material can matter for allergies. For example, the FDA-reviewed patient brochure for one hyaluronic acid lip filler says it should not be used in people with a history of allergic reactions to the bacterial material used to make its hyaluronic acid.
Hyaluronic acid fillers have another practical difference. Clinicians may use hyaluronidase off-label to reduce HA filler; its FDA labeling (for example, Hylenex) covers uses such as helping other injected drugs and fluids disperse, not dissolving filler. It does not dissolve the other filler materials described here. Cleveland Clinic also notes that a provider will ask about bee-venom allergy before using it.
What are calcium hydroxylapatite and poly-L-lactic acid fillers?
Calcium hydroxylapatite is a mineral commonly found in human teeth and bones, according to the FDA, which describes its effects as lasting approximately 18 months. The FDA adds that this material can be visible on x-rays and may obscure underlying features, which is worth mentioning to anyone who takes imaging of your face.
Poly-L-lactic acid is a biodegradable, biocompatible man-made polymer. The FDA notes that it is given as a series of injections over several months and that its effect may last up to 2 years. The FDA adds that its effects generally become more apparent over several weeks, so changes appear gradually rather than right away.
What is PMMA filler, and why does the collagen matter?
PMMA, or polymethylmethacrylate, is a non-biodegradable man-made polymer. The FDA describes PMMA filler as tiny, round, smooth beads that are not absorbed by the body, suspended in a gel-like solution that contains cow (bovine) collagen.
Because the beads stay in the tissue, this type of filler cannot simply fade or be dissolved the way a hyaluronic acid filler can. Bellafill contains bovine collagen and requires an allergy skin test, with a four-week observation period, before treatment; tell your provider about previous collagen reactions.
Why does filler longevity differ?
The material is only part of the answer. The FDA states that how long the effect lasts depends on the filler material and the area where it is injected, and that results depend on the underlying tissue structure and on the volume and type of filler used. Because absorbable fillers are gradually broken down, the FDA notes that the procedure may need to be repeated to keep the added facial volume.
The durations above are approximate, not predictions. In the clinical study described in the RHA 3 patient brochure, the lip filler still had a visible effect in 78 percent of evaluated patients at 12 weeks and in 48 percent at one year. The FDA also notes that the safety of using fillers repeatedly over a long period has not been evaluated in controlled clinical studies, and that it may be difficult or impossible to remove filler material, especially permanent fillers or fillers not made of hyaluronic acid. Ask how long the proposed material usually lasts in the area you want treated, and what a repeat treatment would involve.
What happens during the injection, and why does lidocaine matter?
Filler is an injectable treatment, but the FDA says having it injected should be considered a medical procedure, not a cosmetic treatment. Approved fillers are injected with a syringe and a needle or cannula. Each clinician has their own process. The RHA 3 brochure describes one example: the doctor reviews your medical history, medicines, previous facial treatments and goals, examines and may photograph the treatment area, cleans the skin and may mark the injection sites. The filler is then injected slowly in small amounts, which the brochure says takes 15 to 30 minutes for most patients, and a touch-up may be offered a few weeks later. Ask about limits on exercise, sun and heat in the first day, and when makeup can be applied.
The FDA notes that some fillers contain lidocaine, which is intended to decrease pain or discomfort from the injection. Lidocaine is a medicine, so it adds its own allergy question. The RHA 3 brochure notes that it can leave numbness or tingling around the injection area for a few hours, during which you may not feel heat or cold normally there. The same brochure lists allergic reactions to lidocaine or similar numbing medicines, a history of severe allergic reactions (anaphylaxis) or multiple severe allergies, and bleeding disorders among reasons it should not be used.
Each product has its own labeling. Before treatment, ask for the product name, read its patient information, and give your provider a full list of allergies, medicines and supplements. The FDA also notes that the safety of fillers is unknown during pregnancy, while breastfeeding, and in people under 22, so mention any of these if it applies. For how fillers differ from neuromodulators, read Botox vs dermal fillers.
Some products and methods should not be used at all. The FDA warns that injectable silicone is not approved for any aesthetic procedure, including facial and body contouring or enhancement, and that it can lead to long-term pain, infections and serious injuries such as scarring, disfigurement, embolism, stroke and death. The FDA also states that needle-free devices are not approved for injecting dermal fillers.
The FDA advises not injecting yourself and not buying filler online, because products sold that way could be counterfeit or not approved for use in the U.S. It recommends choosing a health care provider who is trained to perform filler injections. Ask what product is in the syringe and where it came from.
What warning signs need urgent care?
The FDA describes unintentional injection into a blood vessel as one of the most serious risks of any filler. Injury to the blood supply can lead to tissue death, vision problems including blindness, or stroke.
Seek emergency care for any change in vision, or signs of a stroke such as sudden trouble speaking, face drooping, numbness or weakness, severe headache, dizziness or confusion. Seek immediate medical assessment and alert your injector for white, gray or blue skin or unusual pain during or shortly after treatment; do not wait for a callback. Call 911 for trouble breathing or signs of a severe allergic reaction.
Bruising, redness, swelling, tenderness and itching are common after filler. Report these to your provider if they worry you or last longer than you were told to expect, and report any lump or hardening that appears weeks or months later. The FDA lists less common complications, including raised bumps (nodules or granulomas) that may need treatment, infection, and swelling or redness near the injection site after an illness, vaccination or dental procedure. It adds that side effects from any filler can appear weeks, months or years after the injection.
Questions to ask about your filler
- What is the product name, and what is it made of?
- Is it approved for the area you plan to treat?
- Does it contain lidocaine, and do any of my allergies matter?
- Can it be dissolved if there is a problem?
- How long does this material usually last, and what happens as it breaks down?
- Which symptoms should prompt a same-day call or emergency care?
Explore facial aesthetics at Anew Laser MD, or use the contact page to ask which fillers are offered at your location.
Independent sources
- FDA: dermal fillers (soft tissue fillers)
- FDA: FDA-approved dermal fillers (materials)
- FDA: RHA 3 patient information brochure (example hyaluronic acid filler labeling)
- FDA: Bellafill (PMMA collagen) labeling, including the required skin test (P020012)
- Cleveland Clinic: dissolving lip filler
- FDA: Hylenex recombinant (hyaluronidase) prescribing information
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General educational information is not a diagnosis or treatment recommendation. Consult a qualified clinician about your individual circumstances.