Re2O Side Effects: Is a Lump Normal at Week 1?
Feeling a firm spot after Re2O is common with this type of injection. Here's what's normal in the first week, why the particles feel firm, what a lump that shows up weeks later may mean, and which signs mean getting care right away.
Wi Young-jin
Chief Director, Myeongdong
Feeling a firm spot where Re2O went in is a common reaction with this type of injection. With a related product made from pig skin, 31.4% of people had firmness or a lump within 30 days, and swelling and pain settled within a week. A lump that shows up weeks later, or one that turns red, painful or bigger, is different: get it checked instead of waiting it out.
In this article, we'll cover what's normal in the first week, why Re2O can feel firm, what a lump that appears later may mean, the signs that can't wait, and what to mention before treatment.
Quick summary
- Firmness and swelling after Re2O are common injection reactions, while a lump that appears later and turns red, painful or bigger needs a checkup.
- Benchmark: with a related product, 45.4% of 86 people had swelling and 40.7% had pain, and both settled within 1 week.
- In 20 people who had Re2O in one cheek, no serious side effects were seen over 20 weeks, but later reactions weren't studied.
- Skin turning white, gray or blue, or any change in your vision, means getting medical care right away, whatever day it is.
Re2O Side Effects: What's Normal in the First Week?
In the first few days, swelling, pain, redness and bruising are the reactions you're most likely to notice. In a study of 20 people who had Re2O (brand name Elravie Re2O) in the cheek, no serious side effects were seen. The reactions that did appear were brief redness and mild swelling, and they went away without treatment.
Larger numbers come from a related product. A different product, made from pig skin with the cells removed, was injected into the smile lines (nasolabial folds) of 86 people. Here's what they reported within 30 days:
- Swelling: 45.4%
- Pain: 40.7%
- Firmness or a lump: 31.4%
- Redness: 26.7%
- Bruising: 11.6%
The swelling and pain were mild and settled within 1 week with pain relievers or warm compresses. Keep in mind that these figures come from another product used in another area. Read them as a guide to which reactions come first and when they ease, not as Re2O's own rates.
What Is Re2O, and Why Does It Feel Firm?
Re2O can feel firm at first because it carries tiny particles of tissue rather than a gel that spreads like water. It's made from human skin: the cells are removed, and the remaining dermis structure, about 80% collagen, is broken into small pieces. That makes it a skin booster, not a filler. In the Re2O cheek trial, it was placed in the middle layer of the dermis with an automated injector.
*Dermis: the layer under the skin's surface (epidermis) that gives skin its firmness and bounce.
The related pig-skin product doesn't push through a needle as easily as a soft gel, so it was injected with thicker needles (23G and 25G). In the group that got it, 31.4% had firmness or lumps, compared with 23.6% in the group that got a collagen filler. That gap wasn't large enough to count as a real difference statistically.
It helps to note, day by day, whether the firmness feels even across the treated spots and whether it's shrinking along with the swelling. If one spot gets bigger, red or painful, that record helps your doctor make a call faster.
A Re2O Lump Weeks or Months Later: What Does It Mean?
A lump that appears later should be looked at separately from the firmness you feel right after treatment. With injectable fillers, side effects have shown up weeks, months or even years after injection. The Re2O trial only followed people for 20 weeks, so reactions after that point haven't been checked yet.
| When | How it feels | What comes with it | What to do |
|---|---|---|---|
| Within 1 week of treatment | Even firmness where it went in | Swelling and pain that settle within 1 week | Take dated photos |
| New, weeks to months later | One raised lump | Redness, pain or growth | Get checked to find the cause |
| After a cold, vaccine or dental work | Swelling again near the treated spot | Redness | Get checked |
Depending on the cause, a later lump may need injections, oral antibiotics or removal. Even if a lump doesn't hurt and is getting smaller, get seen the same day if it turns red or starts growing again.
Elravie Re2O Side Effects: What Passes and What Can't Wait?
Most swelling and bruising shows up shortly after injection, and many cases settle within a few days to weeks.*
*Based on US FDA guidance on dermal fillers.
If swelling and pain aren't easing after a week, or they're getting worse, have them checked. The signs below come from guidance on dermal fillers, but Re2O also goes into the face through a needle. Don't wait to see whether they pass. Get medical care right away if you notice any of these:
- Skin near the injection site turning white, gray or blue
- Unusual pain
- An open or draining wound, or a sore at the injection site
- Vision changes (go to the nearest emergency room)
- Sudden difficulty speaking, numbness or weakness in your face, arms or legs, difficulty walking, visual changes, face drooping, severe headache, dizziness or confusion (go to the nearest emergency room)
These problems happen when product blocks a blood vessel. The chances are low, but vision problems, including blindness, and stroke have been reported with fillers. Messaging the clinic doesn't replace being seen in person, so get care first.
What Should You Tell Your Doctor Before Re2O?
The injection mixture tested with Re2O also included a hyaluronic acid skin booster, saline and lidocaine, a numbing medicine. That's why an allergy to local anesthetics matters too. It's better to postpone treatment, or at least mention it first, if any of these apply:
- Inflammation or infection where it would go, such as pimples, a rash or hives (wait until it has cleared)
- A bleeding disorder
- Severe allergies or a past anaphylaxis (a sudden, serious allergic reaction)
- An allergy to local anesthetics such as lidocaine
- A tendency to form keloids or thick, raised scars
If you're weighing Re2O for hollows under the eyes, our guide to Re2O under the eyes looks at that question on its own.
Re2O Within Your Travel Itinerary in Korea
Unless you had sedation that day, there's no need to postpone your flight home because of Re2O. The firmness and swelling can still be settling when you board, so a quick note of how the treated spot feels before you leave is useful later.
It also helps to know what one visit can do. Some treatments, like fillers, change your shape the same day. Most others don't transform your face in one go and bring it gradually closer to how it used to look. If more than one session is planned, a single visit doesn't replace the rest of the course.
Once you're back home, you can send photos through the consultation button on this page with questions about a lump or swelling. If a reaction looks serious, get seen by a local doctor first rather than waiting for a reply.
The Bottom Line on Re2O Side Effects
Before you decide, ask what depth Re2O will be placed at in your skin and how many spots are planned. The particles sitting in the dermis are what you'll feel afterward, so that one answer tells you what kind of firmness to expect. Photos taken in the same light and at the same angle on treatment day and at 1 week make it easier to judge whether it's fading.
If side effects are your main concern, talk to your provider before deciding. A good first question is: “How firm should the treated area feel in the first week, and when should I come back?” Beautystone is a clinic in Seoul's Hapjeong area. When you reach out, include the area you're considering, your travel dates, and any filler or skin booster you've had recently with the date.
Sources
- Re2O in one cheek compared with a hyaluronic acid skin booster in the other, 20 people, Int J Mol Sci, 2026
- Multicenter study of a pig-skin dermis particle injection versus collagen filler for smile lines, Aesthetic Plast Surg, 2026
- Common reactions, late lumps, blocked blood vessel signs and what to tell your provider before fillers, US FDA
Frequently Asked Questions
Q. Does Re2O hurt?
A. Re2O and similar dermis-particle injections tend to hurt more often than collagen filler. With a related pig-skin product in the smile lines, 40.7% had pain within 30 days, compared with 10.1% for collagen filler, and it settled within a week. The particles need a slightly thicker needle, which is one reason. The numbing method, such as numbing cream, is decided at the visit based on the area and how sensitive you are.
Q. Re2O is made from human skin. Can it cause an allergic reaction?
A. Re2O is made from skin tissue given by consenting donors and processed under tissue bank standards. The cells are removed, leaving less than 50 ng of DNA per mg, and in Korea it's regulated as a human tissue product. Even so, tell your doctor beforehand if you've had severe allergies or anaphylaxis.
Q. How long does bruising last after Re2O?
A. Bruising after Re2O tends to appear soon after injection and often fades within a few days to weeks. With a related product in the smile lines, 11.6% of 86 people had bruising within 30 days. If the area spreads and the skin turns white, gray or blue, that may be a blood vessel sign rather than a bruise, so get medical care right away.
Q. How is a Re2O lump treated?
A. A Re2O lump is first sorted by timing: firmness right after treatment, or a lump that appeared later. Firmness right after treatment is often watched along with the swelling. A lump that shows up weeks later may need injections, oral antibiotics or removal depending on the cause, as with fillers. Which one it is gets decided by feeling it in person.
Q. Can the Re2O area swell again after a cold or dental work?
A. Swelling or redness near an injection site can rarely appear after a cold or other infection, a vaccine or dental work. This has been reported with fillers, and if the spot where you had Re2O swells again after one of these, get it checked. Mention the date of your treatment and what happened beforehand, since that speeds up the assessment.
Q. Does Re2O have more side effects than other skin boosters?
A. Studies comparing Re2O side effects directly with other skin boosters are still few. In 20 people who had Re2O in one cheek and a hyaluronic acid skin booster in the other, no serious side effects were seen. A related product caused swelling (45.4% vs. 13.5%) and pain more often than collagen filler, but both settled within a week.
Q. How long were Re2O side effects studied?
A. Re2O side effects were studied in 20 people over 20 weeks. The researchers noted that the small group and short follow-up mean long-term results and late side effects can't be judged yet. The related product was followed in 86 people for up to 6 months after the last injection, so anything after that needs a separate checkup.
Q. Can I get Re2O while pregnant or breastfeeding?
A. Safety during pregnancy and breastfeeding hasn't been established even for fillers, and the same caution applies to skin boosters like Re2O. If you're pregnant or breastfeeding, say so at the consultation. Whether to schedule treatment after that period is decided together at the visit.
