PDO threads are not permanent. They are absorbable sutures that dissolve inside the body within 6 to 8 months through a natural process called hydrolysis. The visible results, however, can last 12 to 18 months because the threads stimulate new collagen production that persists after the threads themselves are gone.
How PDO Threads Dissolve
Polydioxanone (PDO) is a synthetic polyester with a molecular structure that includes ester bonds, which makes it naturally biodegradable. Once inserted under the skin, the threads break down through hydrolysis, meaning water molecules gradually split apart the polymer chains. This starts in the softer, less structured regions of the thread material and eventually works into the denser crystalline portions.
The breakdown products are less acidic than those from some other medical polymers, which is one reason PDO is well tolerated in the body. The final byproducts of this degradation are carbon dioxide and water, both of which your body eliminates through normal metabolic processes. Nothing from the thread remains permanently in your tissue.
Why Results Outlast the Threads
The threads do two things while they’re in place. First, they act as a physical scaffold that mechanically lifts or repositions sagging skin. Second, and more important for longevity, they trigger a biological response called neocollagenesis. Your body recognizes the thread as a foreign material and sends fibroblasts (the cells responsible for building connective tissue) to the area. These fibroblasts produce new collagen around the threads, which increases dermal thickness, firmness, and vascularity.
This is why you won’t see results vanish the moment threads dissolve. Right after the procedure, there’s an immediate visible lift from the mechanical support. Over the following months, collagen production adds further skin tightening and wrinkle reduction. On average, the combined effect lasts 12 to 18 months from the date of the procedure, though individual results vary.
What Affects How Long Results Last
Several factors influence both how quickly the threads dissolve and how long the cosmetic effects hold up:
- Thread thickness: Thicker threads have a larger surface area, which stimulates fibroblasts and stem cells more effectively. They also have greater tensile strength, meaning they can hold tissue in place longer before losing structural integrity.
- Thread design: Threads with cogs (small barbs) grip tissue more effectively than smooth mono threads. If cogs are too thin or lack tension, their ability to engage tissue drops quickly, reducing both the lift and the collagen-building effect during absorption.
- Insertion depth and placement: Threads placed at the right tissue depth and along an appropriate lifting vector produce better, longer-lasting results. The toughness of the underlying tissue matters here too.
- Patient age: Patients over 50 may have slightly different outcomes, including a higher risk of minor complications like dimpling.
- Thread expiration: Absorbable threads that are past their shelf life may have already begun degrading before insertion, reducing their effective lifespan.
How PDO Compares to Other Thread Types
PDO threads dissolve faster than the two other common absorbable thread materials. PLLA (poly-L-lactic acid) threads take about 12 months to dissolve and maintain results for roughly 18 to 24 months. PCL (polycaprolactone) threads are the slowest to absorb, taking 12 to 18 months. If longer-lasting results are a priority, your provider may recommend one of these alternatives.
Non-absorbable threads also exist and are technically permanent, meaning they don’t dissolve. However, they carry a higher risk of complications like nerve-related numbness (paresthesia) and thread extrusion, where the thread works its way out through the skin. Absorbable threads like PDO have lower rates of both of these issues.
What to Expect Over Time
In the first few weeks after placement, you’ll see the most dramatic lift. Over the next three to six months, collagen remodeling gradually improves skin texture and tightness. By six to eight months, the threads have fully dissolved, but the collagen framework they stimulated remains. From roughly month 12 to 18, natural aging and gravity will progressively diminish the results.
Because PDO threads are temporary by design, most people who want to maintain results plan for repeat treatments. The procedure is sometimes combined with other treatments, such as muscle-relaxing injections, to address different aspects of facial aging at once. The PDO threads handle sagging and skin laxity, while other treatments target fine lines caused by repetitive muscle movement.