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This article is intended for qualified aesthetic practitioners. It is technical information, not patient advice.
PDO threads are absorbable polydioxanone sutures, pre-loaded into a fine needle or blunt cannula, that are placed in the dermis or subcutaneous fat to tighten, support or lightly lift tissue. Choosing the right one comes down to four numbers printed on every foil pouch: thread type, needle gauge, needle and thread length, and USP suture size. Get those right for the indication and the plane, and most of the planning is done before you open the pack.
Most of what ranks for this topic is written for patients. This piece is for the person holding the pouch: how to read the specification, which configurations suit which areas, and where the practical risks sit.
Polydioxanone is a synthetic, monofilament, absorbable polymer that has been used in surgical sutures for decades. In aesthetic use it does two jobs. Mechanically, the thread sits in tissue and provides support, which is more pronounced with barbed (cog) designs. Biologically, its presence provokes a controlled foreign-body response as it is gradually broken down by hydrolysis, and that response is associated with local fibrosis and new collagen around the thread track.
Two consequences follow for planning. First, because the material is absorbed over a period of months, any mechanical lift from cog threads is temporary by design, and patients should hear that at consultation. Second, the tissue response is part of the intended effect, so placement depth and thread density shape the outcome as much as the thread itself. For a balanced overview of the current evidence, the review Update on Absorbable Facial Thread Lifts in Dermatologic Surgery is a sensible starting point.
A typical listing reads something like "29G 50/70mm 6-0". Broken down:
Reading all three together matters more than any one of them. A 30G 25mm 7-0 mono is a superficial texture thread for small areas. A 27G 50mm 5-0 mono is a sturdier scaffold thread for the lower face or neck. Both are "mono threads", but they are not interchangeable.
Smooth mono threads have no barbs and give no meaningful mechanical lift. Their role is tissue support and skin quality, delivered through a mesh of threads placed in a grid or fan pattern. They are commonly used for crepey skin on the lower face, submental area and neck, around the perioral area and, with very fine short threads, in periorbital skin.
Because the effect builds from density rather than any single thread, planning is about coverage. Map the area, decide on a grid spacing, and keep threads in a consistent plane. A product such as the Intraline Mono 29G 50/70mm 6-0 suits mid-sized areas like the jawline border or lower cheek, where you want enough length to cover ground with fewer entry points.
Mono threads are generally placed in the deep dermis or immediate subdermal plane. Too superficial and the thread can be visible or palpable, particularly in thin or fair skin. Too deep and you lose the dermal response you are aiming for. Resistance on advancement and the visibility of the needle through the skin are your practical guides; if you can see the needle outline clearly, you are too shallow.
Screw threads wrap one strand around the needle; tornado or double-screw designs twist two together; triple and multi-strand threads bundle several fine strands in one carrier. The extra material per entry point gives more local tissue response and a little more body than a single mono.
These designs are usually chosen for small depressed or lax areas where you want more effect per track: fine lines that have not responded to skin boosters, mild volume deficits, or the nasolabial and marionette regions as a supporting layer. The Intraline Tornado 26G 38/50mm 7-0 x2 and the Intraline Triple 26G 50/70mm 7-0 x3 are examples of this category, using finer USP strands bundled on a slightly wider needle.
The trade-off is palpability. More thread in one track means more to feel in thin skin, so keep these to areas with adequate soft-tissue cover and avoid stacking tracks too closely.
Cog threads carry barbs cut or moulded along their length, either in one direction (unidirectional) or two (bidirectional). The barbs engage the subcutaneous tissue and allow you to reposition it along a planned vector. This is the only PDO category that produces a visible mechanical lift on the day.
Cogs are typically delivered through blunt cannulas in the subcutaneous fat. Indications include mild to moderate jowling, lateral brow support, midface repositioning and some neck work. Patients with heavy tissue, marked laxity or thick sebaceous skin tend to get less from them, and a frank conversation about surgical alternatives may serve them better.
Mark the patient upright. Identify the tissue you want to move and the fixed point you are moving it towards, which is usually more superior and lateral and over firmer tissue such as the temporal region or pre-auricular area. Draw each vector so the barbed section sits in the mobile tissue and the anchoring section sits in the stable zone. Threads should run in a consistent subcutaneous plane, and the number of threads per side should match the weight of the tissue rather than a fixed recipe.
As a practical summary:
You can browse the full range of mono, screw, multi-strand and cog options in the PDO threads collection.
Thread procedures carry their own risk profile, distinct from injectables. Common, usually self-limiting effects include bruising, swelling, tenderness and mild asymmetry. Dimpling or puckering is more often seen with cogs and may settle as oedema resolves, though persistent dimpling can need intervention. Less common problems include infection, thread visibility or extrusion, palpable threads, granuloma formation and, with deep or lateral placement, injury to nerves or the parotid duct.
Practical measures that reduce risk:
Any local anaesthesia should follow your own prescribing and clinic protocols.
Threads are single-use sterile devices. Store them in a cool, dry place away from direct heat and sunlight, as directed in the manufacturer's instructions for use, and keep them in their original packaging until the moment of use. Check the pouch is intact and the expiry date is in date before opening, and never resterilise or reuse an opened pack.
Record the product name, lot number and expiry in the patient's notes along with the number, type and location of threads placed. If you ever need to report an adverse incident to the MHRA through the Yellow Card scheme, that traceability is what makes the report useful.
The polydioxanone itself is absorbed over a period of months. Any mechanical lift from cog threads fades as the thread dissolves, while the tissue response around the thread track may persist for longer. Duration varies with the patient, the area and the threads used, so avoid promising a fixed timeframe at consultation.
Mono threads are smooth and used for skin quality and support, placed in a grid with no real lift. Cog threads have barbs that grip tissue and allow repositioning along a vector, so they are the choice when some lift is the aim.
There is no fixed number. It depends on the weight and laxity of the tissue, the thread design and the vectors you plan. Lighter jowling may need only a few cogs per side, while heavier tissue may need more, or may be better suited to a surgical referral.
For mechanical lift, cog threads placed subcutaneously along planned vectors are the relevant category. Mono and screw threads support skin quality but will not lift tissue on their own. Many practitioners combine the two.
Choosing PDO threads is less about brand and more about reading the specification against the job: mono for skin quality, screw and multi-strand for localised support, cog for repositioning, each at a gauge, length and USP size that suits the tissue in front of you. Plan the vector or grid with the patient upright, stay in a consistent plane, keep sterile technique tight and record every lot number. Done that way, threads become a predictable tool alongside fillers and skin boosters rather than a stand-alone promise.
