What is the difference between fillers and biostimulators?

Fillers and biostimulators are two of my favorite aesthetic treatments that give the most impactful results, particularly for people experiencing collagen loss.

One of the most common questions I get asked as a nurse injector is ‘what is the difference between fillers and biostimulators?’ 

Both are great injectable treatments for people who want to look more refreshed, youthful, and refined. These are aesthetic treatments that are specifically made for people experiencing volume loss secondary to decreased collagen. When done by a skilled injector, the finished look will be both natural and transformative.

Let’s go over the main differences between HA fillers and biostimulators. 

Composition

When people talk about filler, they are typically referencing hyaluronic-acid (HA) based fillers. These fillers include popular names like Juvederm, Restylane, RHA, Revanesse Versa, and the newest edition Evolysse. 

Manufacturers create different HA fillers in the same product line (i.e. Juvederm Ultra vs Juvederm Voluma) that are meant to go in different areas of the face. This is because the fillers vary in their stretchiness and how soft or firm they are. So, if I am injecting cheeks, I want something that is more robust and is able to hold structure well. In comparison, if I’m injecting lips, I would want something softer and stretchier so that it moves with your natural mouth movements. 

Because these fillers are all made of hyaluronic acid, this type of filler can be easily dissolved if needed with hyaluronidase, an enzyme that breaks down HA. 

While there are many different kinds of biostimulators that are used globally, I will only be discussing the two that are FDA approved in the United States, which are Sculptra and Radiesse. 

Sculptra is made of poly-L-lactic acid (PLLA). It is made from the same material that is used to make biodegradable sutures. This PLLA comes in a powder form in a vial that is then mixed with sterile bacteriostatic water to make a thin, liquid suspension that’s ready to inject.

Radiesse is made from calcium hydroxylapatite (CaHA) microspheres that are suspended in a gel carrier. Radiesse comes in syringes that contain the CaHa, which will appear as a thick, white, and opaque gel. Radiesse can also be mixed with sterile bacteriostatic saline to make a more liquidy consistency similar to Sculptra. 

Biostimulators are not made of material that is naturally-occurring in our face. Therefore Sculptra and Radiesse can NOT be reversed once injected. However, they do break down over time.

How They Work

HA fillers are the most popular kind of filler on the market. These are the most commonly used dermal fillers because the HA mimics the naturally-occurring hyaluronic acid in our tissues. Hyaluronic acid is hydrophilic, meaning it loves water. Once the HA attracts water, it can expand your tissue in areas where you may be more hollow. HA can also be injected to add hydration to areas like the lips or even be injected superficially as a “skinbooster” – a product that boosts skin quality or hydration. 

When fillers are injected, they provide immediate volumization. With careful product selection and techniques, HA fillers are meant to mimic bone or fat. They provide structural support for areas for areas that are more hollow or need more structure such as cheekbones, jawline, or recessed chins. 

Unlike HA fillers that provide immediate volumization, biostimulators work by stimulating your body’s own collagen production. Once biostimulators are injected into your tissue, the particles signal your fibroblasts (aka cells that create collagen) to create more collagen, which will result in skin that will be more plump, tight, and firm. This process is gradual. 

On average, it takes about 6 weeks to begin to see changes from Sculptra. The changes are going to be very subtle and sometimes hard to tell if you’re looking at yourself in the mirror day by day. You won’t see the full results of it until several weeks later. 

Then there’s Radiesse, which is unique in that it is both a filler and a biostimulator. Therefore you will see some results from Radiesse immediately, but you will also continue to make collagen several weeks after. 

To learn more about Sculptra and Radiesse in depth, read my article about the differences between Sculptra and Radiesse.

Longevity

When people ask me how long my results will last, I always say it depends. Longevity varies from person to person depending on individual factors such as metabolism, lifestyle, and age. They also vary by product selection as well. 

With HA fillers, the body will break down and absorb the HA over time. Generally, HA fillers last 12-24 months on average. However, there are some studies that suggest that there may be remnants of HA that linger in the tissue for much longer. 

With both Sculptra and Radiesse, once your body breaks down and absorbs the original biocompatible material, you are left with the collagen that they created. This collagen that was created by biostimulation lasts 12-24 months on average.

Limitations

While it is technically true that HA fillers stimulate a little bit of collagen, they do not have the same collagen-inducing impact as biostimulators. 

Because HA fillers work by attracting water, too much filler in the wrong places can lead to unwanted outcomes, such as tyndalling (blue tint peeks through the skin), puffiness, or looking too “fake” or “overdone.”

HA fillers carry a higher risk of vascular occlusions (VO) because of their gel-like composition. If a HA filler is injected into a blood vessel, that cuts off oxygen and nutrients that are carried through the blood supply. If left untreated, it can lead to tissue ischemia, necrosis, and even blindness. 

The biggest limitation with biostimulators is that they take time to take effect. Also, depending on how much volume loss you have, it may require several sessions to get the desired results. Full results won’t be seen until several weeks to a few months later. 

Another limitation is once they are injected, they can not be reversed. This means that in the event of any unwanted aesthetic outcome, such as nodules, the injectable itself cannot be dissolved. However, the injector can do other things to reduce the appearance of unwanted outcomes, such as flushing the nodule with saline to try and break it up. 

Biostimulators also can not be injected everywhere in the face. They can not be injected in tear troughs, nose, forehead, lips, and smoker’s lines. 

Which Treatment is Right For Me?

As a nurse injector, I love both treatments. It just depends!

In summary, HA fillers provide instantaneous results with immediate filling effect. HA fillers will correct hollows and deficits. HA fillers are also great because of its ability to mimic bone, which provides lift and structure to areas like cheeks, jawline. and chin. HA fillers can give you the most transformative results in just one appointment. 

Biostimulators on the other hand are treatments that will take time to see full results. This makes them a good option for people who are wanting the most natural results possible. People who want to be more discrete about the aesthetic treatments they had done may favor this option because changes are very gradual. This treatment is also good for people who are wary of filler and don’t want to look overfilled; it is much harder to appear overfilled with biostimulators. 

I love both fillers and biostimulators, but my favorite is using BOTH. I like to use the analogy of building a house. When you use HA fillers, you are building your house– from its bones up and giving it structural integrity. Once you have finished building your house, you need to insure it. Biostimulators are your insurance, as they will help replace the degraded HA fillers and the loss of collagen over time.

Written by: Christy Nguyen BSN

Aesthetic Nurse Injector and Certified Laser Safety Officer