Diluted (hyperdilute) Radiesse: stimulating collagen instead of filling volume

What is diluted Radiesse?

Diluted Radiesse is regular Radiesse, tiny microspheres of calcium hydroxylapatite in a carrier gel, mixed before treatment with saline or with a local anesthetic. Mixing makes it more fluid, so it flows easily through a fine cannula and spreads in an even layer under the skin¹.

In its regular, undiluted form, Radiesse is a filler: it gives immediate volume and is used for folds, the jawline and the back of the hand. When it is diluted, there is almost no immediate volume. What remains is the biological action: the microspheres stay in the skin for a long time and stimulate cells called fibroblasts to produce new collagen around them¹². That is why most doctors consider this use a skin-quality treatment rather than a filling treatment.

Information about the product itself, its registered indications and the controlled trials of the regular form, is on the Radiesse page.

What is the difference between diluted and hyperdilute?

The difference is how much solution is added to the material: at a regular dilution the material still gives the tissue a little support, and at a high dilution, called hyperdilute, it is used almost only to stimulate collagen. The 2018 international consensus describes both levels and matches them to different areas, according to skin thickness and the goal¹.

A 2026 review tried to organize the variety of published protocols, and proposes classifying them by degree of dilution, the injection layer and the clinical goal. The authors stress that this is a descriptive framework only, because most of the data come from pilot studies, case series and consensus².

The doctor sets the dilution level for each area according to the skin at the examination. There is no single dilution that suits everyone.

Who is diluted Radiesse suitable for?

Diluted Radiesse mainly suits people whose skin has become thin, lax or covered in fine crepey wrinkles, not people who lack volume or have a large amount of excess skin. It works on the quality of the skin itself, so the result is subtle and gradual.

• Thin, wrinkled skin, such as fine lines on the neck and décolletage, or skin on the arms that looks like crepe paper.
• Mild to moderate laxity in the cheeks, along the jawline or under the chin.
• Skin changes after weight loss or pregnancy, on the abdomen and arms, when there is no significant excess skin.
• Wide, depressed acne scars, usually as part of a combination of treatments. Details on the Radiesse for acne scars page.

People with a large amount of excess skin, significant sagging or prominent neck bands will get limited improvement from a diluted injection. In such cases the examination also covers other options, such as dissolvable threads, botulinum toxin or surgery.

How is the injection done?

The injection is usually done with a cannula, a fine tube with a rounded tip, inserted through a few entry points, through which the material is fanned out under the skin. The consensus describes injection into the layer just under the skin, with even distribution and small amounts per pass, followed by massage of the area so the material spreads evenly¹.

1. Examination and marking: assessment of skin thickness, laxity and movement of the area, and marking of the treatment area.
2. Preparing the material: mixing Radiesse with the solution until the mixture is uniform.
3. Injection: a few entry points, and spreading the material with a cannula in fan-shaped movements.
4. Massage immediately after the injection, to smooth out the mixture.

The treatment usually takes less than an hour. Afterwards there may be swelling, redness and small bruises at the entry points, which usually resolve within days⁸.

How many treatments are needed, and when is a change seen?

Usually a series of several treatments is planned a few weeks apart, and the improvement builds slowly, over weeks to months, because that is how long the skin takes to produce collagen. The consensus describes repeat treatments according to the area and the response, not a single treatment¹.

In the first weeks there is hardly any visible change, and sometimes the swelling of the first day gives a misleading impression. The real change is felt gradually, in the texture, elasticity and overall appearance of the skin. How long the effect lasts depends on age, skin quality, sun exposure and the area, so maintenance treatments are usually planned.

Important to know: a 2024 systematic review notes that there are still no controlled trials of diluted injection in the face, so expectations should rest on an honest explanation at the examination, not on a promise⁴.

Is diluted Radiesse approved?

In the United States, Radiesse at a 1:2 dilution was approved in 2026 for décolletage wrinkles. Other diluted uses, such as on the neck, arms or abdomen, are off-label. The international consensus itself also defines diluted injection for skin tightening as a new off-label use¹³.

A 2026 review of uses outside the face concludes that most uses on the body are still off-label, and that calcium hydroxylapatite is approved in the United States for the back of the hand and the décolletage⁵.

In Israel, Radiesse is listed in the Ministry of Health medical device registry (AMAR) as an "aesthetic filler," for use by a physician. The listing does not specify areas or dilutions, so diluted injection in areas not tested in trials is an off-label use⁷. Off-label use is accepted practice in medicine, but it requires an explanation of what is known and what is not yet known, and a shared decision.

What are the risks?

The common effects are swelling, redness and small bruises, and the best-known complication of calcium hydroxylapatite is small nodules under the skin. In a review of 21 studies with more than 2,700 patients, nodules made up most of the reported side effects, and about half of them appeared in areas that move a lot. Most nodules were not visible and resolved without treatment⁶.

• The material cannot be dissolved with an enzyme, unlike hyaluronic acid. That is why the dilution, layer and distribution are especially important.
• Mobile areas and thin skin, such as the neck, are more prone to nodules, so a high dilution and the correct layer are used there.
• Blood vessel occlusion is a rare complication of all fillers and requires immediate treatment⁸.

Details on each effect and what is done about it are on the Radiesse side effects page.

Who is it not suitable for?

It is not injected during pregnancy or breastfeeding, when there is active inflammation or infection in the area, or when there is a tendency to unusual reactions to fillers, until this is clarified. According to the FDA, the safety of fillers has not been tested in pregnancy, breastfeeding or under age 22⁸.

Tell the doctor before treatment about blood thinners, clotting disorders, autoimmune diseases, allergies and a tendency to thick scars. Do not stop a prescribed medication on your own.

How is it done at Dr. Dana Buchbut's clinic?

Dr. Dana Buchbut, physician (M.D.), examines the skin herself and injects herself. Diluted Radiesse is one of the collagen stimulators at the clinic, alongside Sculptra and Aesthefill, and the choice between them is made according to the area, skin thickness and the goal.

For depressed acne scars, when subcision is performed, Dr. Dana always combines a collagen stimulator, diluted Radiesse or Aesthefill, together with PRP. The reason: subcision releases the fibers that pull the scar inward, the collagen stimulator builds new tissue and supports the area so the depression does not return, and PRP brings growth factors from the patient's own blood that speed up healing and tissue building.

Before treatment, the doctor explains what is known from research and what is not yet known, and that diluted use in most areas is off-label. After treatment there is a follow-up, to check the response and plan the next session.

Terms on this page: Radiesse (CaHA) · dissolvable threads · botulinum toxin · hyaluronic acid · vascular occlusion · Sculptra (PLLA) · Full glossary

The information on this page is general educational information only and is not a substitute for an examination, diagnosis or personal medical advice. The decision on treatment is made only after an examination.