Biostimulator injections are aesthetic treatments that rejuvenate the skin by leveraging the body’s natural regenerative capabilities. Unlike traditional dermal fillers, which instantly add volume using a gel-like substance, biostimulators prompt the body to create its own new tissue. These injectables are composed of biocompatible materials introduced into the deeper layers of the skin, such as the dermis. This process gradually restores lost structure and firmness, offering a subtle, natural-looking improvement over time.
The Science of Collagen Induction
The fundamental action of a biostimulator is to initiate neocollagenesis, the formation of new collagen. When injected into the dermis, the material triggers a controlled, mild inflammatory response. This response is the body’s natural reaction to the foreign particles, attracting specialized immune cells called macrophages.
These macrophages then secrete growth factors, which activate fibroblasts, the skin’s primary collagen-producing cells. Activated fibroblasts begin laying down a network of new collagen fibers, initially depositing Type III collagen, which is later remodeled into the stronger Type I collagen. This regenerative process creates a new structural scaffold within the skin, leading to improved skin thickness, elasticity, and firmness.
The material acts as a temporary framework or signal for the cells, and the eventual aesthetic result is achieved by the patient’s own newly synthesized collagen. This biological mechanism leads to long-lasting improvements in skin quality that continue to evolve over several months.
Primary Types of Biostimulatory Materials
The most widely used biostimulatory materials are Poly-L-lactic acid (PLLA) and Calcium Hydroxylapatite (CaHA).
Poly-L-lactic Acid (PLLA)
Poly-L-lactic acid (PLLA) is a biocompatible, synthetic polymer composed of microscopic particles. Once injected, PLLA slowly degrades through non-enzymatic hydrolysis, breaking down into water-soluble molecules. These breakdown products are eventually metabolized into carbon dioxide and water, being completely eliminated from the body over a period of 18 months or more. The PLLA particles act as a scaffold promoting new collagen growth before the material is fully absorbed. Its effect is purely gradual, focusing on long-term stimulation with minimal immediate volume.
Calcium Hydroxylapatite (CaHA)
Calcium Hydroxylapatite consists of smooth, spherical micro-particles suspended in a gel carrier. Unlike PLLA, CaHA often provides some immediate volume from the gel, which is then gradually absorbed. The CaHA microspheres stimulate fibroblasts to produce new collagen and elastin. While the gel is absorbed, the CaHA micro-particles remain to sustain the collagen-building process before they are also metabolized by the body over time.
Common Treatment Areas and Results
Biostimulators are frequently used to address areas of volume loss and skin laxity that occur with aging across the face and body. On the face, common sites include the temples, mid-face, cheeks, and jawline. They also improve skin quality in areas like the neck, décolletage, and hands.
The results from these injections are characteristically gradual, reflecting the time required for the body to produce new collagen. Patients typically begin to see subtle improvements in skin texture and firmness within a few weeks. Full results are observed several months after the initial treatment, generally appearing over a period of three to six months as the collagen network matures.
Because the outcome relies on the body’s regenerative response, multiple treatment sessions are often required to achieve optimal correction. The sustained collagen production leads to long-lasting benefits, with results often enduring for up to two years or more, depending on the material used and individual patient factors.
What to Expect During and After Treatment
A biostimulator injection session is a minimally invasive procedure, often completed in under an hour. The treatment area is typically numbed with a topical anesthetic before the material is injected into the deeper layers of the skin using a fine needle or a blunt-tipped cannula. Following the injections, the practitioner may massage the treated area to help evenly distribute the product and minimize the risk of lump formation.
Short-term side effects are common but usually mild, including temporary swelling, redness, and tenderness at the injection sites. Minor bruising is also possible, which generally resolves within a few days. Patients are usually advised to avoid strenuous exercise, excessive heat exposure, and alcohol for the first 24 to 48 hours to minimize swelling and bruising.
For materials like Poly-L-lactic acid, patients are often instructed to follow a specific at-home massage protocol: massaging the treated areas for five minutes, five times a day, for five consecutive days. This aftercare instruction ensures the product is evenly dispersed, supporting uniform collagen stimulation and helping prevent the formation of palpable nodules.