# Biostimulators: Collagen-Stimulating Facial Injections > Biostimulators are substances injected into the face that stimulate the skin's own collagen production. How they differ from fillers, where they are used,… Published: 3 November 2026 · Medically reviewed by: Op. Dr. Murat Alpay **Biostimulators are substances injected into the face that stimulate the skin's own collagen production. How they differ from fillers, where they are used, when results appear, their risks and who should not have them.** Biostimulators are substances that, when injected into the face, **stimulate the skin's own collagen production**. Unlike hyaluronic acid fillers, which fill a space immediately, they aim to activate the collagen-producing cells (fibroblasts) in the deeper layers of the skin. In everyday language this approach is sometimes called a "liquid facelift." It is not an operation, however, and it does not replace a surgical facelift; the sources describe it as an injection approach with a gradual result, for people who have facial volume loss and laxity and are not considering surgery. This article explains how biostimulators work, how they differ from fillers, where they are used, when results appear, their risks and who should not have them. For general information see our [filler](https://www.muratalpay.com.tr/en/tedaviler/dolgu/) page, and for types of fillers see [what is facial filler](https://www.muratalpay.com.tr/en/blog/yuz-dolgusu-dermal-filler-nedir-turleri-ve-riskleri/). ## What Is a Biostimulator? Biostimulators are substances that are compatible with the body and break down on their own over time. They are described not as passive fillers that only take up space but as substances that stimulate cells in the tissue. The three groups most often mentioned for the face are: - **Poly-L-lactic acid (PLLA):** A synthetic substance from the same family as the dissolvable surgical suture material. It comes as a powder and is mixed with a liquid before injection. - **Calcium hydroxylapatite:** Contains tiny calcium-based microspheres in a gel carrier. - **Polycaprolactone:** A long-lasting medical polymer made of small microspheres in a gel carrier. What matters is less the product name than the type of substance, the area treated and the technique of the physician. ## How Does It Work? When the microspheres or particles are placed in the tissue, they start a mild, controlled inflammatory response in the deeper skin, a kind of "foreign body reaction." This stimulates the collagen-producing cells. Over time **type 1 and type 3 collagen** and elastic fibres increase. The substance itself gradually breaks down into water and carbon dioxide and is cleared by the body. So the result comes less from the injected substance than from the new tissue your body produces. That is why the effect is gradual. ## How Does It Differ From Hyaluronic Acid Filler? - **Source of volume:** Hyaluronic acid binds water and gives volume as soon as it is injected. With biostimulators, the volume in the first days comes largely from the carrier fluid and swelling and recedes within days. The real firming and fullness arrive over weeks as your own collagen forms. - **Reversibility:** Hyaluronic acid filler can be dissolved with a special enzyme (hyaluronidase) if needed. Poly-L-lactic acid, calcium hydroxylapatite and polycaprolactone **cannot** be dissolved with this enzyme. This is why technique and area choice matter so much. - **Visibility on X-ray:** Calcium hydroxylapatite can be seen on X-ray and CT; hyaluronic acid cannot. If you have had it, it is sensible to tell your physician before imaging. - **Duration:** Sources report about 18-24 months for poly-L-lactic acid, 12-18 months for calcium hydroxylapatite and 1-4 years for polycaprolactone. These vary from person to person. ## Where Is It Used? Biostimulators are usually considered for: - The mid-face and cheekbone area - The jawline and chin - Temple hollows - Lines from the nose to the lips and from the corners of the mouth downward - The neck, décolleté and back of the hands **Areas that are avoided** include the eye area, the body of the lips and the area around the mouth, where the skin is very thin or the circular muscles are very active. The risk of firm lumps (nodules) is high there, so poly-L-lactic acid and calcium hydroxylapatite are not recommended. ## Who Is It Considered For? The sources describe this approach mainly for people with general loss of facial volume (a "hollowed" look) and laxity, who want a natural, gradual renewal and are not considering surgery. Who is suitable is decided at the examination, looking at facial structure, skin quality, expectations and medical history. Where wrinkles rather than volume loss are the main concern, other methods may be more suitable. For other skin-renewal approaches such as mesotherapy see our [mesotherapy](https://www.muratalpay.com.tr/en/tedaviler/mezoterapi/) page. ## When Are Results Seen? How Many Sessions? - **Results:** The first collagen response begins in about 1-2 months. The full result usually appears in 3-4 months, and in 3-6 months according to some sources. So a clear result is not expected right after the procedure. - **Sessions:** Usually 3-5 sessions are planned at 4-8 week intervals at first. The gap between sessions is waited out so the effect of the previous one can be assessed. - **Maintenance:** The sources note that a yearly reminder session may be suggested to sustain the effect. - **Approach:** The sources stress a "less is more" principle. Under-correction is preferred over trying to correct too much in the first session. ## How Is It Done? The substance is placed deep under the skin or just above the bone. Placing it at the surface of the skin or inside the muscle is not advised because of the nodule risk. After the procedure, some substances, especially poly-L-lactic acid, need a massage programme described by the physician so the product spreads evenly. In the sources this programme is mentioned as 5 times a day, 5 minutes each, for 5 days; the right programme depends on the substance and the person and is set by the physician. ## What Are the Risks and Side Effects? - **Temporary effects:** Swelling, bruising, redness and tenderness. Swelling can be more noticeable with biostimulators than with fillers. It usually settles within days. - **Nodules and papules:** Firm lumps that can be felt under the skin without pain may form. Placement too close to the surface, an unsuitable technique or inadequate massage increases this. Treatment of these lumps can include massage, breaking them up with a needle, treatments given into the lump, or rarely surgical removal. Hyaluronidase does not dissolve these substances. - **Blocked blood vessel:** A very rare but serious complication. If the needle enters a vessel or pressure from outside restricts it, tissue circulation can be impaired. Slow injection, checking by drawing back and using a suitable needle tip or cannula lower the risk. - **Late granuloma:** Rarely, lumps caused by a strong reaction of the body to the foreign substance can appear months later. Because of these risks, the procedure should be performed by a physician who knows facial anatomy well and can manage complications. ## Who Should Not Have It? - People with an active infection or inflammation in the area to be treated - During pregnancy and breastfeeding - People with a known hypersensitivity to the product's components or to the local anesthetic used (an anesthetic that numbs the area) - People with an active autoimmune or connective tissue disease or taking drugs that suppress immunity (for some substances the opinion of the relevant specialist is needed) - People with a bleeding disorder or taking blood thinners - People with unrealistic expectations or a body image disorder ## What to Watch for Afterwards - In the first 24 hours, avoid touching the area, wearing makeup and heavy exercise - In the first days, stay away from hot baths, saunas and steam baths - Use intermittent cold application for swelling and bruising - Protect yourself from the sun and use the sunscreen your physician recommends regularly - Follow the massage programme your physician describes - See your physician without delay if you notice a firm lump, increasing pain, colour change or redness ## Frequently Asked Questions ### Does a biostimulator replace a surgical facelift? No. A biostimulator is an injection approach; it does not surgically reposition the skin and tissues. If sagging is marked, the suitable method is decided at the examination. ### Are the results seen immediately? No. The volume in the first days comes largely from swelling and the carrier fluid and recedes. The real result forms over weeks and months as your own collagen is produced. ### Is it used together with hyaluronic acid filler? The sources describe approaches in which fillers, biostimulators and neurotoxins are planned together. Which combination is needed is decided for each person. ### Can it be reversed if something goes wrong? Hyaluronic acid filler can be dissolved, but biostimulators cannot be dissolved with this enzyme. This makes planning and area choice before the procedure even more important. ### Is it done around the eyes and lips? Because the nodule risk is high in these areas, the sources do not recommend poly-L-lactic acid and calcium hydroxylapatite there. Results of any surgical or interventional procedure may vary from person to person. It is recommended that you get detailed advice from your physician before the procedure. Written and reviewed by **Op. Dr. Murat Alpay** Specialist in Obstetrics and Gynaecology · Istanbul University, Istanbul Faculty of Medicine (Çapa) [Full biography →](https://www.muratalpay.com.tr/en/hakkinda/) [← All posts](https://www.muratalpay.com.tr/en/blog/) --- Original page: https://www.muratalpay.com.tr/en/blog/biyostimulatorler-nedir-kolajen-uyaran-yuz-enjeksiyonlari-kimlere-uygun/ Last updated: 2026-11-03 Op. Dr. Murat Alpay — Specialist in Obstetrics and Gynaecology Op. Dr. Murat Alpay Practice, Tekelioğlu Cd. No:51 B Kat:2, Filo Apt., 07160 Muratpaşa / Antalya 0505 351 77 88 · Monday – Saturday 09:00 – 18:00 · Closed on Sunday *This information is for general guidance only and does not replace examination, diagnosis or treatment.*