Dermal fillers fall into four main categories based on what they’re made of: hyaluronic acid, calcium hydroxylapatite, poly-L-lactic acid, and polymethylmethacrylate. The first three are temporary and gradually absorbed by the body over months to years. The fourth is the only FDA-approved permanent filler. Beyond these synthetics, fat transfer from your own body is a fifth option. Each type works differently, lasts a different amount of time, and suits different goals.
Hyaluronic Acid Fillers
Hyaluronic acid (HA) fillers are by far the most popular type. Hyaluronic acid is a sugar molecule your body already produces naturally in your skin, joints, and eyes. It’s remarkably good at holding water: a single gram can retain up to six liters. When injected as a gel, it physically fills space under the skin, attracting and binding water to plump the area instantly. You see results the same day.
Brand names you’ll encounter include Restylane (the first non-animal-derived HA filler to market), Juvederm, and Belotero. These products come in different thicknesses for different purposes. Thinner formulas work for fine lines and lips, while thicker versions add volume to cheeks or jawlines. Depending on the product and where it’s placed, HA fillers last 6 to 12 months, though deeper injections can last up to two years with newer formulations.
The biggest advantage of HA fillers is reversibility. An enzyme called hyaluronidase can dissolve them if something goes wrong or you don’t like the result. This is considered the gold standard safety net, and it’s the reason many practitioners recommend HA fillers for first-timers. No other filler type can be reversed this way.
Calcium Hydroxylapatite Fillers
Calcium hydroxylapatite (CaHA) is the same mineral found naturally in your bones and teeth. In filler form, sold as Radiesse, it consists of tiny microspheres (25 to 45 microns in diameter) suspended in a water-based gel. This gives it a dual action: the gel provides immediate volume, while the microspheres create a scaffold that your skin cells use to build new collagen over the following months.
CaHA fillers are thicker and firmer than HA, making them well suited for structural areas like the jawline, chin, cheeks, and nasolabial folds (the lines running from your nose to the corners of your mouth). They’ve also been used for hand rejuvenation. Because the product is denser, it’s generally not used in the lips, where a softer filler is needed. Results typically last 12 to 18 months. Unlike HA fillers, CaHA cannot be dissolved with an enzyme if you’re unhappy with the outcome.
Poly-L-Lactic Acid Fillers
Poly-L-lactic acid (PLLA), sold as Sculptra, works completely differently from the fillers above. It doesn’t fill space directly. Instead, it triggers a controlled response in your skin that stimulates your cells to produce new collagen. The PLLA particles act directly on the collagen-producing cells in your skin, significantly increasing their output. The material itself is gradually absorbed, but the collagen it helped build stays behind.
This means results aren’t immediate. Improvements develop over two to three months and can continue building for up to six months after treatment. Most people need a series of sessions spaced several weeks apart to reach their goal. The tradeoff for this slower timeline is longevity: because you’re rebuilding your own structural support rather than relying on injected material, results can last two years or longer. PLLA is especially popular for treating broad volume loss across the cheeks, temples, and lower face rather than filling a single line or crease.
PMMA Fillers: The Only Permanent Option
Polymethylmethacrylate (PMMA) is the only non-absorbable filler material the FDA has approved. Sold as Bellafill, it contains roughly six million tiny PMMA microspheres suspended in bovine (cow-derived) collagen gel with a small amount of lidocaine for comfort. The collagen gel provides immediate volume while the microspheres remain permanently in the tissue, stimulating ongoing collagen production around them.
Bellafill is FDA-approved specifically for nasolabial folds and acne scars. Because it’s permanent, there’s no going back easily if you’re unsatisfied, which makes it a bigger commitment than temporary options. A skin test is required beforehand to rule out an allergy to the bovine collagen component. In clinical use, it has shown high patient satisfaction and a good safety profile, but the permanence is a double-edged sword: if complications arise, they’re harder to manage than with absorbable fillers.
Fat Transfer
Fat grafting uses your own body fat as a filler. Fat is harvested from the abdomen or thighs through a gentle form of liposuction, minimally processed, then reinjected into the face. Because the material comes from your own body, there’s no risk of allergic reaction.
The procedure is more involved than a standard filler appointment. Harvesting fat requires local anesthesia and can cause some discomfort, bruising, and soreness at the donor site. Results can last up to two years, which is comparable to some of the longer-lasting synthetic fillers. Fat transfer tends to appeal to people who want a natural material and don’t mind the extra complexity, or those who need larger volumes of correction than synthetic fillers can practically deliver in a single session.
Biostimulators vs. Traditional Fillers
One useful way to think about fillers is by dividing them into two functional categories. Traditional volumizing fillers, like HA and the gel component of CaHA, work by physically occupying space under the skin. You get instant plumping because the product itself creates volume. Biostimulatory fillers, like PLLA and the microsphere component of CaHA, trigger your body to rebuild its own collagen and structural support over time.
This distinction matters for expectations. If you want visible improvement before a wedding next weekend, a volumizing HA filler makes sense. If you’re more interested in gradually reversing broad facial volume loss over several months, a biostimulator may produce more natural-looking, longer-lasting results. Some products, like Radiesse, straddle both categories by offering immediate volume plus long-term collagen stimulation.
Common Side Effects
Most side effects from injectable fillers are mild and temporary. In a large meta-analysis of HA filler treatments, swelling was the most common reaction, occurring in about 41% of patients. Bruising affected roughly 11%, pain about 10%, and lumps or bumps about 9%. Redness occurred in around 5% of cases. These typically resolve within days to two weeks.
Serious complications are rare but real. Vascular occlusion, where filler is accidentally injected into or compresses a blood vessel, can cause tissue damage or, in the worst cases, vision loss. A review of vascular complication cases found that blindness accounted for the majority of severe reports, with only about 28% of those cases showing partial or full recovery. This is why choosing an experienced, qualified injector matters enormously, and why the reversibility of HA fillers with hyaluronidase is such an important safety feature.
What the FDA Has and Hasn’t Approved
The FDA groups approved dermal fillers into absorbable (temporary) materials, which include hyaluronic acid, calcium hydroxylapatite, and poly-L-lactic acid, and non-absorbable (permanent) materials, which includes only PMMA microspheres. Liquid silicone and silicone gel are not approved for injection anywhere in the body for filling wrinkles or augmenting tissue.
The FDA has also issued specific warnings about unapproved versions of popular products circulating in the U.S. Juvederm Ultra 2, 3, and 4, for example, are not approved for use in the U.S. and have been sold through online retailers. Approved fillers are prescription devices that should only be injected by or under the direction of a licensed provider. If a deal seems unusually cheap or the product name doesn’t match what’s on the FDA’s approved list, that’s a red flag worth paying attention to.