Juvelook vs Rejuran:
a collagen stimulator and a skin booster, side by side

Juvelook vs Rejuran: what each is, and the difference

Juvelook and Rejuran are both injected into the skin of the face, and both are talked about as skin treatments, so they are often weighed against each other. What is in the syringe is different, and that decides how each works, what it is used for and what can be done if something goes wrong.

Juvelook is a collagen stimulator made by VAIM in Korea: microspheres of poly-D,L-lactic acid (PDLLA), a biodegradable polymer, in a carrier of non-cross-linked hyaluronic acid, supplied as a powder and mixed with liquid before injection. A clinical study describes it as PDLLA with hyaluronic acid (Yi 2026). It sits between a skin booster and a filler. Juvelook Volume, sold internationally as Lenisna, carries more PDLLA in each vial and is used for volume rather than skin quality. More on the product is in Juvelook in Singapore.

Rejuran is a skin booster made by PharmaResearch in Korea: chains of polynucleotide purified from salmon DNA, filtered and sterilised so that what is injected is the polymer, not genetic information. Rejuran Healer, the facial preparation, carries polynucleotide at about 20 mg/mL. It contains no particles and adds no volume. The range also includes Rejuran I, a thinner preparation for the skin around the eyes; Rejuran S, a thicker one placed into and around scars; and Rejuran HB, which combines polynucleotide with hyaluronic acid. More on the range is in Rejuran in Singapore.

Put simply, Juvelook leaves particles in the skin that the body responds to by laying down collagen, and Rejuran leaves no particles and is directed at how the skin repairs itself. The table sets the two side by side.

Swipe sideways to see the whole table.

When a reaction after Juvelook or Rejuran cannot wait

Most reactions after Juvelook or Rejuran are the expected ones described below. Both are injected into the face, though, and any injection into the face can rarely block a blood vessel. The warning signs are the same as after filler:

Urgent: a change in vision or eye pain after filler: call 995 now. Skin that turns pale, dusky or mottled, or pain that is getting worse, needs urgent assessment by the doctor who injected you, or at A&E, now. See the warning signs of a blocked blood vessel after filler.

Signs of a stroke (new weakness of the face, an arm or a leg, or slurred speech): call 995 now, and do not travel to a clinic first. For any of these signs, do not wait for a reply to a message or for a booked review.

Skin that is dying after a blocked blood vessel (necrosis) is an emergency. It needs urgent, more intensive care than a lump does, starting now. A blocked blood vessel is never treated with the Sculpting mode or any other laser.

Hyaluronidase acts on hyaluronic acid only. In an emergency such as a blocked blood vessel it is not delayed for a skin test, and it acts on the hyaluronic acid in Juvelook's carrier or in Rejuran HB, but the poly-D,L-lactic acid microspheres and polynucleotides are not dissolved by hyaluronidase, so care is also urgent and supportive, with referral where needed.

These reactions are not for waiting out either:

• Redness that is spreading, with a fever; feeling faint, confused or very unwell; or swelling around the eye with pain: call 995 or go to A&E now.
• Difficulty breathing, a tight throat, swelling of the tongue or throat, or swelling that spreads quickly across the face, after any injection, including hyaluronidase, can be a serious allergic reaction: call 995 now. Itch, hives or swelling that spreads beyond the treated area: contact the clinic that injected you the same day.
• A red, hot, painful, swollen or draining lump, or a fever: possible infection or inflammation. See a doctor the same day; if no doctor can see you today, A&E. It is treated medically first, before any device and before any talk of surgery.

Until you are seen, do not squeeze, massage or try to drain a red or painful lump yourself, and do not have more product injected into the area.

“For hard lumps from mixed products, I use one tool, Time Freeze Laser LCLR®, to target the material without surgery.”

Dr Sin YongOn hard lumps from mixed fillers and skin boosters

How Juvelook and Rejuran work

Juvelook: particles that prompt collagen

Juvelook has two parts that behave differently. The hyaluronic acid carrier holds water and gives some hydration on the day, and the body absorbs it. The PDLLA microspheres are the active part: the body responds to them by laying down its own collagen around them while the polymer slowly breaks down. A review of PDLLA in dermatology describes it as biodegradable and biocompatible, used for skin firmness, wrinkles and scar remodelling (Lee 2024). Because the change depends on the body's own collagen response, it builds gradually rather than appearing on the day.

Where microspheres gather in one place, the same response that builds collagen can build a lump. That is why placement, depth and even mixing matter with Juvelook, and why a lump that lasts is scanned before anything is decided.

Rejuran: a repair signal, with no particles

Rejuran works on the repair environment of the skin rather than on its bulk. Two effects are described: an influence on fibroblast activity and the turnover of the matrix around them, and signalling through adenosine A2A receptor pathways, which is also the route of its described anti-inflammatory action. The polynucleotide also holds water in the tissue. It changes no dimension of the face: it does not fill, does not lift and does not remove pigment, and skin that is signalled to repair still has to do the repairing.

A systematic review of polynucleotides in aesthetic medicine found 9 studies, with 219 patients, of low and moderate quality; injections improved wrinkles, texture and elasticity in several of them, and the authors call for more rigorous studies (Lampridou 2024).

Side by side in one laboratory study

In a laboratory and mouse study, PDLLA, a polynucleotide filler and a calcium hydroxylapatite filler each raised collagen-fibre density, skin elasticity and signals of new blood-vessel growth in aged mouse skin (Oh 2023). That was in mice, not people, and it does not show how either product behaves in a face. No study cited on this page compared Juvelook with Rejuran in people.

What each is used for: fine lines, texture, acne scars and under the eyes

Both are skin treatments, so their uses overlap at the edges, but they are chosen for different reasons. Neither is a lift: sagging is a different problem, and more product is not the answer to it.

Fine lines, texture and pores

Juvelook is used where skin quality is the concern and a gradual collagen response is wanted: fine lines, texture and enlarged pores, with some hydration from its hyaluronic acid on the day. Rejuran is used for texture, fine lines, elasticity and skin that is thin, damaged or red, where repair rather than volume is wanted. A pore is a fixed opening and no injection shrinks it; what can change is how the skin around it looks.

Acne scars

Acne scars are several different things: rolling scars tethered to deeper tissue, boxcar scars with fixed walls, ice-pick tracts, and redness or pigment that is not scarring at all. Neither product releases a tether or reshapes a fixed wall; that is the work of subcision, resurfacing or TCA CROSS. Within a scar plan, Juvelook is considered where fine lines sit over shallow scars and a slow collagen response is wanted, and a review lists scar remodelling among the uses of PDLLA (Lee 2024). Rejuran S, the thicker polynucleotide, is placed beneath depressed scars to support the skin-quality part of the plan, alongside structural scar work. Which, if either, fits depends on the scar type. More is in acne scar treatment and Rejuran S for acne scars.

Under the eyes

Under the eyes the skin is thin, and different problems look alike: crepey skin, a hollow, pigment and an eye bag. Rejuran I is a thinner polynucleotide preparation made for the skin around the eyes, used for crepey skin and fine lines; it does not fill a hollow, treat a bag or remove pigment, and bruising is more likely there. With Juvelook, microspheres placed close to the surface of thin skin can show as bumps: in one case report, firm nodules appeared 3 weeks after Juvelook was injected into the tear troughs (Seo 2025). Granulomas, a reaction of the body to the material, are a different problem: in one case after PDLLA around the eyes, with the product not named, they formed in both lower eyelids of a 67-year-old woman (Garlaschi 2026). Dr Sin Yong can use Juvelook under the eyes, but he prefers energy-based treatment there (FSX Laser for the skin, and the Restore arm of the VF Lift for hollow areas); if Juvelook is used, it is decided only after examination and a scan of any earlier filler. The cause under the eye is diagnosed before anything is chosen. More is in FSX Laser, the VF Lift, Rejuran I for under-eye skin and dark eye circle treatment.

Who each tends to suit, and who should wait

Who each suits follows from what the skin is short of, decided at examination rather than by the name on the enquiry.

Juvelook tends to suit

• Skin that needs some hydration on the day and a gradual collagen response: fine lines, texture, enlarged pores and shallow acne scars.
• Someone prepared for gradual change, and for a decision that cannot be fully reversed, because the PDLLA is not dissolved by hyaluronidase; a lump can still be treated without an incision.

It does not suit someone who wants an immediate change, whose main problem is sagging, or for whom reversibility matters most: a hyaluronic acid filler or booster is the category that can be dissolved.

Rejuran tends to suit

• Thin, fragile, damaged or textured skin, fine lines and reduced elasticity, where repair rather than volume is wanted.
• Skin recovering from acne, as one part of a wider plan; and, with Rejuran I, crepey skin around the eyes once the cause has been diagnosed.

It does not suit someone who wants volume, a lift, pigment cleared or a scar released. Because it is purified from salmon DNA, a fish or salmon allergy is asked about directly, and a different skin booster may be chosen.

Who should wait, or be assessed carefully, for either

• Pregnancy or breastfeeding: treatment is deferred.
• Active infection, a cold sore, an acne flare or inflamed skin at the injection sites: settled first.
• Blood-thinning medicines or a bleeding tendency, and a tendency to keloid scarring where injecting near scars: weighed and discussed first. Never stop a prescribed medicine on your own for a cosmetic treatment.
• A history of granulomatous reactions: caution with any particle-based product, Juvelook included.
• Lumps, heaviness or unevenness from earlier injections: an ultrasound scan of what is already there comes before anything is added.

How the skin booster classes are matched to the skin is set out in skin boosters in Singapore, and how the collagen stimulators differ in collagen biostimulators in Singapore.

What is normal afterwards, and what is not

Both are placed as a series of small injections, and the skin reacts straight away. The first reactions look alike; what changes later, and what is judged at review, is different.

After Juvelook

Small raised bumps at the injection points, swelling, redness, tenderness and bruising are expected, and they ease steadily as the area settles. Some of the early fullness is the liquid the powder is mixed with, and swelling, so the look on the day is not what is judged: the collagen response comes later and is judged at review. In a study of 20 people treated with Juvelook for the folds between the nose and the mouth, only temporary swelling and bruising were reported, with no nodules, granulomas or delayed reactions up to 3 months after the last session (Yi 2026).

After Rejuran

Small raised bumps at each injection point are expected, with redness, swelling, tenderness and sometimes bruising, more so around the eyes where the skin is thin. The bumps flatten as the swelling settles and the polynucleotide is taken up, and changes in texture develop gradually rather than on the day. In a study of polynucleotide injections into the lips of 30 people, every one had swelling 30 minutes afterwards, 90% had pain and 77% redness, and the reactions were mostly mild and transient (Rho 2025). The two studies looked at different areas at different times, so their figures cannot be compared with each other.

What is not normal, after either

What is not normal is a reaction that lasts, builds or changes character:

• A bump that has not flattened once the rest of the area has settled, or a firm lump that appears later: have it reviewed and scanned. After PDLLA, a lump can appear months later: in one published case, with the product not named, swelling and granuloma-like nodules began 4 months after injections along the jawline and cheeks (Perez-Willis 2024).
• A red, hot, painful, swollen or draining lump, or a fever: a doctor the same day; if no doctor can see you today, A&E. It is treated medically first.
• Pale, dusky or mottled skin, or pain that is getting worse: urgent assessment by the doctor who injected you, or at A&E, now. A change in vision or eye pain: call 995 now.
• Difficulty breathing, a tight throat, swelling of the tongue or throat, or swelling that spreads quickly across the face, after any injection, including hyaluronidase, can be a serious allergic reaction: call 995 now. Itch, hives or swelling that spreads beyond the treated area: contact the clinic that injected you the same day.

More detail is in Juvelook side effects and skin booster side effects.

Side effects and complications: what the published evidence shows

No injection is free of risk. For both products, most side effects are temporary injection reactions, and the serious risks are those of any injection into the face: infection and, rarely, a blocked blood vessel or a serious allergic reaction, whose signs and what to do are set out above. The published evidence on both is small.

Juvelook and other PDLLA

• A clinical study. In 20 people treated with Juvelook, only temporary swelling and bruising were reported, up to 3 months after the last session (Yi 2026).
• A review. A review of PDLLA in dermatology flags granulomas and non-inflammatory nodules as possible complications that need monitoring and early intervention (Lee 2024).
• An expert consensus. Brazilian experts who set out how to reconstitute, place and dose the PDLLA microspheres of another brand, Aesthefill, not Juvelook, name nodules and granulomas as the problems to keep to a minimum, and note that clinical trials remain limited (Magacho-Vieira 2024).
• Case reports. Firm nodules under the eyes 3 weeks after Juvelook (Seo 2025); swelling and granuloma-like nodules 4 months after PDLLA along the jawline and cheeks, where ultrasound showed several nodules (Perez-Willis 2024); and granulomas in both lower eyelids after PDLLA that did not settle with saline, radiofrequency or medical treatment injected into them, and needed two operations (Garlaschi 2026). The second and third reports do not name a product.

Rejuran and other polynucleotides

• A systematic review. Across 9 studies of low and moderate quality, with 219 patients, side effects of polynucleotide injections were generally mild and transient (Lampridou 2024).
• A lip study. After polynucleotide injections into the lips of 30 people, swelling, pain and redness were common at 30 minutes and mostly mild and transient (Rho 2025).
• What else can happen. Less often, nodules form where material sits unevenly or too close to the surface, and infection can follow any injection. Allergic reaction is rare; a fish allergy is asked about directly because Rejuran is purified from salmon DNA.

Case reports show that a problem can happen, not how often it happens. The published evidence does not yet show how often lumps follow either product.

Can Juvelook or Rejuran be dissolved?

Hyaluronidase, the enzyme used to dissolve hyaluronic acid filler, acts on hyaluronic acid only.

• Juvelook: hyaluronidase can dissolve the hyaluronic acid carrier, but the PDLLA microspheres are not dissolved by hyaluronidase, just as poly-L-lactic acid (Sculptra) is not. The carrier is absorbed in the weeks after treatment, so a firm lump that lasts is usually the microspheres.
• Rejuran: polynucleotides are not dissolved by hyaluronidase. Where a preparation also contains hyaluronic acid, as Rejuran HB does, the enzyme acts on that part only.

So neither can be reversed the way a hyaluronic acid filler can. Material that cannot be dissolved can still be treated without an incision: Dr Sin Yong treats it with the Sculpting mode of Time Freeze Laser LCLR®, as set out below. Many polynucleotide bumps settle on their own as the swelling goes; one that stays is scanned before anything is decided. How hyaluronidase is used is explained in hyaluronidase.

A lump that lasts: ultrasound first, then treatment without an incision

A lump that lasts after Juvelook or Rejuran can be product gathered in one place, hyaluronic acid from another filler or booster, a granuloma, fluid, infection or something unrelated, and from the outside they can feel the same. Juvelook's own hyaluronic acid carrier is absorbed in the weeks after treatment, so a lump that lasts is rarely the carrier. Ultrasound shows where the product sits, how deep it is and how far it has spread, and what it is likely made of; it does not prove what a lump is, and where it does not look like product, further tests are arranged. An international consensus of 15 experts calls ultrasound mandatory for managing filler complications (Velthuis 2025). Dr Sin Yong performs the scan himself, and then:

• Red, hot, tender, swollen or draining: a doctor the same day (A&E if no doctor can see you today). It is treated medically first, before any device and before any talk of surgery. Hyaluronic acid is dissolved only once an infection is under control, and no laser or other device is used on an active infection.
• Hyaluronic acid, usually from a filler or booster in the same area, is dissolved only if the lump is the hyaluronic acid itself, after a skin test. Before planned dissolving, Dr Sin Yong always does a skin test: a small amount of hyaluronidase is injected just under the skin to check for a reaction. A small first dose follows, reviewed at about 48 hours, because dissolving more than the excess can leave a hollow. In an emergency such as a blocked blood vessel, hyaluronidase is not delayed for a skin test, but the PDLLA microspheres and polynucleotides are not dissolved by it; see when a reaction cannot wait, above.
• What cannot be dissolved: Dr Sin Yong treats lasting lumps of PDLLA or polynucleotide, and lumps where several products sit together, with the Sculpting mode of Time Freeze Laser LCLR®, his own protocol on a long-pulsed 755 nm and 1064 nm laser platform, without an incision. Like any laser, it can cause blistering or a change in skin colour, so settings are chosen for your skin. Under the eyes, settings are kept conservative and the eyes are protected. Where hyaluronic acid sits with other material, the two are planned in order. A blocked blood vessel is never treated with the Sculpting mode or any other laser.
• A small lump that cannot be seen can sometimes be left alone and reviewed; the scan decides.

The detail is in Juvelook lumps, lumps after skin boosters, hyaluronidase allergy and the skin test, infection after filler and other injections and the Sculpting mode of Time Freeze Laser LCLR®.

A lump after Juvelook or Rejuran, and only offered surgery? Get assessed first

Some patients with a lump after Juvelook or Rejuran are told that it has to be cut out, or that nothing can be done because the product cannot be dissolved. It is true that the PDLLA in Juvelook and polynucleotides are not dissolved by hyaluronidase. Material that cannot be dissolved can still be treated without an incision. Before you agree to an operation, know what it means:

• A scar. Every cut through the skin of the face heals with a scar.
• A dent. Cutting out a lump takes tissue with it, and the area can heal hollow or uneven.
• Nerve injury. Nerves that give the face feeling and movement run close to where filler sits. An injured nerve can leave numbness, or weakness in a smile, a lip or a brow.
• Product left behind. Filler spread through tissue is hard to remove completely.
• No way back. Tissue that has been cut out cannot be put back.

In one published case, PDLLA granulomas in both lower eyelids needed two operations (Garlaschi 2026).

In Dr Sin Yong's practice, almost every hard lump is treated without surgery. If yours is one of the few that needs surgery, you are told plainly, and why. Inflammation and infection are treated medically, hyaluronic acid is dissolved after a skin test if it is the lump itself, and Dr Sin Yong treats what cannot be dissolved with the Sculpting mode of Time Freeze Laser LCLR®, without an incision.

Surgery has a place. An abscess may need draining, which is a smaller procedure than cutting a lump out, and a lump that does not look like product on the scan may need a tissue sample. The point is the order: scan first, decide after. Being scanned first closes no door: an operation can still be done later if it is ever needed, but once done it cannot be undone. If you have already been offered one, Dr Sin Yong can scan the lump and give you a second opinion before you decide. What removal surgery involves is set out in filler removal surgery, and lumps after any filler or skin booster in hard lumps after filler or skin boosters.

Tried other treatments and almost given up?

Many patients who come to see Dr Sin Yong about lumps after Juvelook or Rejuran tell him they have tried almost everything else and had given up hope. Having tried other treatments does not mean nothing more can be done: what is done next depends on what the scan shows.

That history is useful. Knowing what was injected, when, and what has already been tried often explains why a problem has stayed: hyaluronidase acts only on hyaluronic acid and only where it reaches, some fillers are not hyaluronic acid at all, and swelling or fluid can look like filler. Ultrasound shows which of these applies, and the plan starts from there. For material that cannot be dissolved, Dr Sin Yong uses the Sculpting mode of Time Freeze Laser LCLR® for nodules large and small, without an incision. How each person responds varies.

If you have been told nothing more can be done, it is still worth having the area scanned: ultrasound shows what is there, and the plan is made from that. Bring any records of past treatments, product names and dates if you have them. More on this is in when filler dissolving has not worked.

How Dr Sin Yong approaches Juvelook and Rejuran

Dr Sin Yong offers both on Orchard Road and performs every injection himself. He starts with what the skin is short of: hydration and a gradual collagen response, repair of thin or damaged skin, volume, or lift. Juvelook and Rejuran answer only some of these, and sagging is a lifting problem. He asks what has been injected before, and where earlier filler or boosters are involved, he scans the area with ultrasound before anything is added: the PDLLA in Juvelook and the polynucleotide in Rejuran are not dissolved by hyaluronidase, although a lump after either can still be treated without an incision. Fish allergy, pregnancy, active skin infection and any keloid tendency are asked about first.

The preparation, placement and number of visits are set after examination; this site does not publish session counts or intervals. A consultation can end with either product, a different treatment or no treatment. He also manages lumps after either product: you do not need to have been treated here. He developed the Time Freeze Laser LCLR® protocol himself and has been invited to share his clinical expertise in Seoul, Dubai, Bangkok and São Paulo, including as a Global Key Opinion Leader. Choosing between skin boosters more generally is covered in which skin booster suits me and Profhilo vs Rejuran.