Before a GOURI injection — what this product changes

This is not a list of prohibitions. What we are trying to do is separate the cautions that come from actual data, the ones that are custom, and the ones whose source cannot be traced. With that separation you can decide what to ask in your consultation.

Hyaluronidase is an enzyme that breaks down hyaluronic acid. Polycaprolactone is not hyaluronic acid, so the enzyme does nothing to it. The literature states of the polycaprolactone class that it does not respond to hyaluronidase and may require invasive removal. The detail is in hyaluronidase — what can be reversed and what cannot.

So this is the question we ask first in consultation — “are you in a situation where you need to be able to undo the result?” If a wedding or another fixed date is close and you want to keep that option, the right place to look is cross-linked hyaluronic acid, not this class.

One misreading to avoid. “Cannot be reversed” does not mean “stays for life”. Polycaprolactone is a degradable material, and the manufacturer states that degradation in the body takes 6–12 months. Irreversible means there is no way to remove it on demand, not that it is permanent. Note also that those 6–12 months are the degradation time of the material, not the duration of the effect.

Our position, stated plainly. We are not saying that list is wrong. Pregnancy and breastfeeding, active infection and autoimmune disease are situations in which injectables are customarily excluded or postponed, and we apply the same standard. But it should be said that this is a convention across the whole class, not a finding verified for this product. Otherwise it gets misquoted as “the GOURI trials found it dangerous”.

How to check the licence yourself. Article 20 of the Korean Medical Devices Act requires manufacturers and importers to print the licence number on the container or outer packaging. Asking a clinic for the licence number of a product is an entirely normal step, and once you have it you can look up the precautions yourself in the MFDS device database. The method is in what one licence number tells you, and what it does not.

The accurate answer is neither “dangerous” nor “fine” but “there is no data”. We found no study that injected liquid-form polycaprolactone into people with autoimmune disease and followed them. The same is true for pregnancy and breastfeeding. The only thing that can be relied on here is that injectable trials excluded such patients from the outset.

• Pregnancy and breastfeeding — elective cosmetic treatment is customarily postponed. Not because harm has been shown, but because safety has never been tested. There is no reason to proceed with an unhurried treatment in the absence of data.
• Autoimmune disease, or ongoing immunosuppression — a delayed inflammatory reaction to a foreign material is a theoretical concern, but nothing confirms or excludes it for liquid-form polycaprolactone. Tell the injector about disease activity and current medication; if the disease is active, we advise waiting.
• A previous severe reaction to an injectable — which product, what reaction, and when. This is essential to say before choosing an irreversible material.

Do not read “no data” as “safe”. It is a principle this site repeats — not reported and does not happen are different statements. With 33 people observed and published, it is more accurate to say that a rare reaction has not yet had the chance to be seen.

Swelling, nodules or pain appearing weeks to months after an injectable is called a delayed inflammatory reaction. Across fillers the reported incidence is 0.3–4.25%, and the proposed triggers include infection, vaccination, biofilm and protein impurities. An expert panel has moved away from calling these “hypersensitivity” in favour of the broader term “inflammatory”, precisely because the cause is not one thing.

Polycaprolactone has a case too. A delayed-type hypersensitivity reaction to a non-hyaluronic-acid polycaprolactone filler following COVID-19 vaccination has been reported. That was a microsphere product, not the liquid form. We found no such case with the liquid form — which, again, is not evidence of rarity but a statement about 33 people observed.

So our guidance is this. If a vaccination or dental procedure is scheduled, it is better not to have them overlap with the injection. There is no firmly evidenced interval, and we could not find any source that gives one. The practical reason is that overlapping timing means that if something appears later, it cannot be attributed. If you currently have inflammation anywhere — a cold, a dental infection — we advise waiting until it has resolved.

“Do not layer several irreversible materials at once” — that is the rule we work to. If several things go in on the same day, then when something appears months later there is no way to tell which one it came from. We state plainly that this is a way of deciding, not a research finding.

GOURI is designed to be placed from the dermis to the dermal–subcutaneous junction, and the published reports used either a 31G needle or a 25G cannula. Shallow does not mean vascular problems are off the table. Across injectables, the site and the instrument set the character of vascular complications — this is covered in adverse events by booster class and needle or cannula.

Across fillers, vascular complications with visual loss are rare but recover poorly — in a series of 365 new cases, complete recovery was 6.0% and no recovery 68.2%. Those figures are for fillers in general, not for liquid-form polycaprolactone. We found no vascular complication case with liquid PCL — and, once again, 33 people have been observed.

So the advice we can give here is about the procedure rather than the product. Where anatomically risky areas are involved (glabella, nose, around the eyes), you are entitled to ask about experience in that area and the plan if something goes wrong. And remember that being an irreversible material narrows the options for that plan.

This section is about safety rather than about the product, so it belongs here even though there is no liquid PCL data behind it. These are signs to report immediately after any injectable.

• The injection site or the skin around it turns white, or a red net-like mottling appears
• Pain during or straight after the injection that is unusually severe and does not settle
• Blurred vision, eye pain, or double vision — contact someone at once
• Swelling that worsens on one side only, or that is red, hot, painful and growing
• Fever, or pus
• A new firm lump appearing weeks or months later — this can be the form a delayed inflammatory reaction takes

Do not wait it out. With signs suggesting a vascular problem — blanching, net-like mottling, severe pain, visual change — time decides the outcome. Contact the clinic that treated you first; if you cannot reach anyone, go to an emergency department. The normal course of bruising and swelling is in bruising and swelling — how much is normal and for how long, and nodules in nodules after treatment.

What we most want to leave you with is not a list to memorise. It is that this product has no “dissolve it if there is a problem” option, and that most of the cautions in circulation are class convention rather than anything verified for this product. Go into your consultation holding those two facts and it becomes clear what to ask.

Written and reviewed by Lee Chi-Hak, MD, medical director of Miso Clinic in Daegu, South Korea. Every study cited above is given together with its design, its size and the limitations the authors themselves recorded, and where we could not find data, we have said that we could not find any.