Radiesse is made of calcium hydroxylapatite (CaHA) microspheres suspended in a water-based gel called carboxymethylcellulose (CMC). By weight, the microspheres make up 30% of the product and the carrier gel makes up 70%. This two-part composition is what sets Radiesse apart from hyaluronic acid fillers: it provides immediate volume from the gel, then stimulates your body to build new collagen as the microspheres interact with surrounding tissue.
The Two Main Ingredients
Calcium hydroxylapatite is a mineral that naturally exists in human bones and teeth. In Radiesse, it’s manufactured into smooth, uniform microspheres, tiny enough to pass through a needle but large enough that your immune cells don’t immediately clear them away. These particles are biocompatible, meaning your body recognizes them as a familiar substance rather than a foreign invader.
The carrier gel, carboxymethylcellulose, is a water-soluble material derived from cellulose (plant fiber). It serves two purposes: it keeps the microspheres evenly distributed throughout the syringe so they inject smoothly, and it provides the initial volume correction you see right after treatment. Think of the gel as a temporary scaffolding that holds everything in place while the microspheres do their longer-term work.
How the Ingredients Break Down Over Time
The carrier gel dissipates first, gradually absorbing into your body over the weeks following injection. As the gel disappears, the CaHA microspheres remain at the injection site, where they activate fibroblasts, the cells responsible for producing collagen. This process, called neocollagenesis, is why Radiesse is classified as both a filler and a biostimulator.
Eventually, your body breaks down the microspheres too. Immune cells called phagocytes dissolve the CaHA into calcium and phosphate ions, the same minerals your body already uses. CT scans show that CaHA is clearly visible immediately after injection, but only residual amounts remain at 12 months. The collagen your body built around the microspheres persists after the filler material itself is gone, which is why results can last beyond the life of the product.
How Radiesse Differs From Hyaluronic Acid Fillers
Most popular injectable fillers (Juvederm, Restylane) are made of hyaluronic acid, a sugar molecule naturally found in skin. One practical difference in composition matters: hyaluronic acid fillers can be dissolved with an enzyme called hyaluronidase if something goes wrong or the results aren’t what you wanted. Radiesse cannot be dissolved this way. Calcium hydroxylapatite does not respond to hyaluronidase, so once it’s injected, you’re waiting for your body to metabolize it naturally.
This isn’t necessarily a drawback for most people, but it does mean placement accuracy matters more. If too much is injected or it ends up in the wrong spot, correction options are limited compared to hyaluronic acid fillers.
FDA-Cleared Uses
The FDA first approved Radiesse in December 2006 for correcting moderate to severe facial wrinkles and folds, particularly the nasolabial folds (the lines running from your nose to the corners of your mouth). It has since gained additional clearances for hand volume loss and jawline contouring.
A version called Radiesse Plus allows the product to be mixed with 2% lidocaine before injection, resulting in a final lidocaine concentration of 0.3%. This simply adds a local anesthetic to reduce discomfort during the procedure. The active filler ingredients remain the same.
Hyperdilute Radiesse for Skin Tightening
Beyond its use as a traditional filler, practitioners increasingly dilute Radiesse with saline or lidocaine to create a thinner mixture that can be spread over larger areas like the neck, chest, and hands. This “hyperdilute” approach focuses on collagen stimulation rather than volume. The idea is to distribute microscopic CaHA particles across a broad surface to improve skin texture and reduce fine wrinkling.
Dilution ratios typically range from 1:1 (equal parts Radiesse and saline) to 1:4 (one part Radiesse to four parts saline), depending on the treatment area and the patient’s age. Higher dilutions spread more thinly and are often used in younger patients or areas with thinner skin, while lower dilutions deliver more concentrated stimulation for older skin with greater laxity. Consensus guidelines from dermatology groups have endorsed ratios of 1:1 to 1:2 for skin tightening on the face and body.
Common Side Effects
Because Radiesse is made of biocompatible materials, most reactions are related to the injection itself rather than the filler’s composition. In FDA clinical trials tracking 175 patients for 28 days after treatment, the most common responses were swelling (85.7% experienced some degree, though most was mild), lumps or bumps at the injection site (73.7%, again mostly mild to moderate), and redness (39.4%). Only one patient in the trial experienced severe swelling and bruising, which resolved within 16 days without additional medical treatment.
The lumps and bumps statistic can sound alarming, but this largely reflects the normal feeling of filler settling beneath the skin in the first few weeks. About 10.9% of patients had an injection site mass noted as an adverse event. Because CaHA is radiopaque (it shows up on X-rays and CT scans, just like bone), you should let any imaging provider know you’ve had Radiesse so they don’t mistake the particles for something concerning.