Polynucleotide Injections for Sagging Skin: Realistic Expectations

What causes sagging skin, and which kind can polynucleotides help?

Sagging has two main causes: skin-quality laxity, where the skin itself thins and loses elasticity, and structural descent, where ligaments loosen, fat pads shift and bone changes. Polynucleotides can improve the first. They cannot reverse the second, which needs tightening devices, filler, threads or surgery.

When patients say “my skin is sagging” they may mean very different things. One person notices that the skin on their neck has a fine crepe texture and feels loose when they turn their head. Another sees heavy jowls that blur the jawline. A third dislikes the papery, creased skin under their eyes. All three are called sagging, yet the tissue causing each problem sits at a different depth, and each responds to different treatments.

The study behind the 80% figure contains a useful nuance. Flament and colleagues compared sun-seeking and sun-avoiding women in Clinical, Cosmetic and Investigational Dermatology and found that pigmentation problems were strongly linked to UV, whereas ptosis, the loss of firmness that makes tissue droop, was linked mainly to chronological ageing. In other words, the deeper sagging of the lower face is largely driven by time and anatomy, while the thin, weathered, crepey quality of the skin over it is where sun damage and skin-quality treatments play a bigger part.

How do polynucleotides improve lax skin?

Polynucleotides are purified salmon or trout DNA fragments that form a water-binding, scaffold-like gel in the dermis and are thought to calm inflammation and support fibroblasts, the cells that make collagen and elastin. Over weeks, thin skin can become more elastic and resilient, so fine crepiness and looseness look less obvious.

The firming effect of polynucleotides is indirect. They do not contract tissue like heat-based devices, and they do not physically hold tissue up like threads. Instead they aim to improve the dermis, the supportive layer of the skin. A 2024 review in the International Journal of Molecular Sciences describes polynucleotides as long-chain, higher molecular weight molecules with a scaffold structure, distinct from the shorter PDRN fragments used in wound healing. The proposed benefits for skin include hydration, better elasticity and reduced inflammation.

That mechanism explains both the strengths and limits. Where laxity comes from thin, depleted skin, a thicker and more elastic dermis makes a visible difference: the neck creases less, the under-eye looks less papery, and skin on the chest stops folding when you lean forward. Where laxity comes from tissue sitting lower on the face, better-quality skin is welcome but the contour stays largely the same. For the full background on how polynucleotides work, see our complete guide to polynucleotide treatment.

Neck, jawline and under-eye: where polynucleotides help most

Polynucleotides give the most visible benefit on the neck, décolleté and under-eye, where skin is thin and crepiness is the main issue. Along the jawline and lower face they improve the skin envelope but will not remove jowls. Crepey skin on the upper arms and above the knees may also respond, usually needing a full course.

The neck

Neck skin is thinner than facial skin, has fewer oil glands and is often neglected in sun protection, so it shows crepiness early. Polynucleotides placed across the front and sides of the neck can soften fine horizontal lines and improve that crinkled texture. They do not treat prominent vertical platysmal bands, which are muscle, or a heavy fold under the chin caused by fat and loose deeper tissue. Those need a different approach, such as HIFU for mild to moderate laxity or a surgical opinion for advanced change.

The jawline and lower face

Early jowling usually reflects both descent of deeper tissue and thinning skin. Polynucleotides can help the skin over the jawline look tighter and smoother, which can sharpen the appearance of the jawline slightly in people with mild change. For a visible lift, energy-based tightening, strategic filler support or, in more advanced cases, surgery are more appropriate. Combining polynucleotides with a device often gives a more complete result than either alone.

Crepey under-eye skin

The lower eyelid has some of the thinnest skin on the body. When it loses elasticity it creases finely, looks papery and can make the eyes appear tired. This is one of the best-studied uses of polynucleotides. In a prospective study of 42 patients published in the Journal of Cosmetic Dermatology in 2026, two sessions of intradermal polynucleotides three weeks apart improved patient-reported scores for the lower eyelids and crow’s feet at 1, 3 and 6 months, with the greatest improvement at 3 months. Fat bags, heavy hooding and a deep tear trough are different problems, which our eye and under-eye treatment page covers.

Décolleté, arms and knees

Sun-damaged chest skin that creases when you lean forward often responds well to a course of polynucleotides. Crepey skin on the inner upper arms and above the knees can improve too, but these areas have larger surface areas and thinner evidence, so expect to need a full course and maintenance, and consider radiofrequency skin tightening where looseness is more marked.

What does the evidence show for polynucleotides and laxity?

Direct evidence on laxity is limited but positive. A 2025 systematic review reported a statistically significant reduction in sagging at 18 weeks in one included trial, and a 2026 real-life study rated neck improvement moderate or better in over 93% of cases. Most studies are small, and none show a surgical-style lift.

It is worth being precise about what has been measured. Most polynucleotide research focuses on wrinkles, texture, hydration and elasticity rather than sagging as such. The systematic review by Lampridou and colleagues in the Journal of Cosmetic Dermatology included nine studies with 219 patients, and noted that one trial by Kim and colleagues found a statistically significant reduction in sagging at 18 weeks. The authors also judged the overall evidence to be of low to moderate quality.

The honest conclusion is that polynucleotides are a reasonable, low-risk way to improve the quality of lax skin, particularly on the neck and under the eyes, but they are not a substitute for structural treatment. That is also the conclusion of a 2026 review in the Journal of Clinical Medicine comparing polynucleotides with hyaluronic acid filler under the eyes: the two are complementary, with filler reserved for structural correction and polynucleotides for dermal quality.

Polynucleotides vs HIFU, radiofrequency and thread lifts

HIFU uses focused ultrasound to heat deeper layers and has the strongest evidence for mild to moderate lifting. Radiofrequency heats the dermis to tighten and improve texture. Threads physically reposition tissue but carry more side effects. Polynucleotides improve skin quality with minimal downtime and are often combined with a device.

The microfocused ultrasound review by Contini and colleagues is especially helpful for setting expectations. Across 16 studies, measurable lifting was real but small: brow lifts of 0.47 to 1.7 mm and a reduction in submental area of 26 to 45 mm² on side photographs. Excessive laxity and a BMI above 30 were relative contraindications because results declined as laxity increased. Treatment was described as moderately painful, and rare adverse effects, such as altered sensation or bruising, affected about 2% of patients.

Radiofrequency sits between the two. A 2025 systematic review in Aesthetic Surgery Journal Open Forum pooled 15 studies with 1,230 participants and found texture improved in 71% to 100% of patients, firmness in 52.9% to 100%, and satisfaction of 82% to 100%, with mild, transient side effects and a mean pain score of 1.94 out of 10. Threads can produce a more immediate change but, in a 2026 meta-analysis, visible or palpable threads affected about 10% of patients and skin dimpling 7%.

Can polynucleotides be combined with HIFU or radiofrequency?

Yes. Combining treatments is common because they work on different layers: a device tightens deeper tissue or the dermis, and polynucleotides improve the skin over it. Treatments are usually spaced a few weeks apart. A split-face trial found that adding polynucleotides to radiofrequency microneedling gave faster improvement in periorbital wrinkles.

The strongest direct evidence for combining comes from a randomised split-face study by Yogya and colleagues in Dermatology and Therapy. Thirty people with periorbital wrinkles had three sessions of radiofrequency microneedling two weeks apart, with polynucleotides applied to one side of the face and saline to the other. At two months, 3D imaging showed faster improvement on the polynucleotide side. No serious adverse events occurred. It is one small study, but it supports the logic of pairing a collagen-stimulating device with a skin-quality injectable.

1. Assessment and photographs

   Your practitioner examines skin quality, laxity and underlying structure, and photographs you from the front, both sides and at 45 degrees so that jawline and neck changes can be judged fairly later.

2. Structural treatment first, where needed

   If deeper laxity is present, a tightening treatment such as HIFU or radiofrequency is usually planned first, because collagen remodelling after heat treatment develops over the following weeks and months.

3. Polynucleotide course

   Polynucleotide sessions follow, typically 2 to 3 sessions spaced 2 to 4 weeks apart, focusing on the neck, jawline skin, under-eye or décolleté.

4. Review at around 3 months

   Results are compared with baseline photographs. This is also the time to decide whether anything else, such as filler for volume support, would add value.

5. Maintenance

   Polynucleotides are commonly topped up every 6 to 12 months. Our HIFU page notes that results can last 12 to 18 months, so device maintenance is planned separately.

What results can you realistically expect, and when?

Expect firmer-feeling, smoother, less crepey skin rather than a lift. Hydration may improve within 1 to 2 weeks; the main change builds over 2 to 3 months. Improvement is gradual, varies between people and fades without maintenance, so judge it against standardised photographs, not the mirror.

Non-surgical tightening of every kind is subtle, and the gap between clinician and patient ratings in the HIFU review shows how easy it is for expectations to drift. Agreeing specific goals before treatment helps. “My neck skin looks less crinkled when I look down” is realistic. “My jowls disappear” is not.

Timing matters too. Treatment makes more sense well ahead of an event: at least four to six weeks for skin to settle after the first session, and ideally three months to see the full effect of a course. Results then fade gradually. Daily SPF 30 or higher, a sensible retinoid routine where appropriate and not smoking all help an improvement last.

What is recovery like after polynucleotides for the neck and under-eye?

Recovery is short. Small raised bumps settle within hours to a day, mild swelling within 1 to 2 days, and any bruising, which is more likely on the neck and under the eyes, within about a week. Most people return to work the same day, avoiding heat, exercise and alcohol for 24 to 48 hours.

Side effects reported in studies are mostly mild: the Lampridou review lists localised pain, swelling, itching, redness and bruising that generally resolved within a week, and no severe adverse events. In the 42-patient periorbital study, adverse events were minimal, mainly mild swelling and discomfort in the first couple of days, with no delayed complications during six months of follow-up.

Risks, and who should not have polynucleotides for sagging skin

Polynucleotides have a favourable safety profile in published studies, but they are not risk-free. Rare risks include infection and allergic reaction. Avoid treatment in pregnancy or breastfeeding, with a fish allergy, or with an active skin infection, and discuss autoimmune conditions, bleeding disorders and blood thinners first.

Compared with thread lifts, which in a 2026 meta-analysis caused swelling in 34% and bruising in 26% of patients, polynucleotides are gentler. Compared with HIFU, they avoid the moderate treatment pain and the rare nerve or burn-related effects reported in about 2% of cases. The trade-off is that they do less for true structural sagging. Safety still depends heavily on hygiene, anatomy knowledge and a medically trained injector.

The CQC states that it does not regulate cosmetic injections used to alter appearance, so check your practitioner’s professional registration. The NHS recommends meeting the person who will treat you beforehand, asking about the most common complications and what happens if something goes wrong, and being given time to decide.

How much does treating sagging skin cost in London?

In London a polynucleotide session for the neck or face typically costs £250 to £400, and a course of three about £600 to £1,000. A full face and neck HIFU session is typically £500 to £1,200. Combined plans are quoted together after assessment. All figures are indicative.

When comparing costs, think in terms of the year rather than the session. A single HIFU treatment may cost more upfront but last longer, while polynucleotides are cheaper per visit but need a course and maintenance. Our article on how much non-invasive facial rejuvenation costs shows example yearly budgets.

Treating lax skin at Levirgo in Knightsbridge

Levirgo Aesthetics Clinic, at 6 Beauchamp Place, Knightsbridge SW3 1NG, is a doctor-led clinic a short walk from Harrods and a few minutes from Knightsbridge station on the Piccadilly line. We assess skin quality and structure separately, then recommend polynucleotides, HIFU, radiofrequency, filler or a combination.

Because we offer polynucleotides, HIFU and skin tightening under one roof, there is no incentive to fit your face to a single treatment. Your consultation starts with what bothers you, then looks at the layer causing it. We photograph your baseline from several angles, explain what each option can and cannot achieve, and give you an itemised written plan.

Many of our patients travel from Belgravia, Chelsea, Sloane Square and Kensington. If you would like to talk it through first, contact the clinic, or book a consultation online. You can read more in our skin treatments journal.