Is 2 mL Enough? Reading a Korean Skin Booster Injection Plan

2 mL is the volume in one syringe of Rejuran Healer, and many questions about Korean skin boosters come back to numbers like it. I'm Dr. Hongseok Kim, a board-certified dermatologist with 21 years of experience, and at VOS Dermatology Clinic in Gangnam I do the consultation and the injection myself. I'm writing this for readers who were told at home that boosters are hype, or that their skin is too thin, scarred or reactive for them, and who want the numbers on a plan explained before deciding anything.

A Korean skin booster injection places a small volume of a regenerative or hydrating substance, such as polynucleotide (PN) or hyaluronic acid, into the dermis through many shallow microinjections. The goal is skin quality: texture, hydration, fine lines and elasticity. It doesn't add volume like a filler, and the change builds over a course of sessions rather than appearing on the day.

Why can't a serum stand in for the needle?

Large molecules don't cross intact skin in useful amounts. Bos and Meinardi set this out in Experimental Dermatology in 2000 as the 500 Dalton rule: compounds that work through the skin surface are almost always under about 500 Da. Polynucleotides are chains of DNA fragments, far larger than that.

So a 'PN serum' and a PN injection share an ingredient name and end up in different places. The serum mostly stays on top; the injection goes where fibroblasts, the cells that make collagen and elastin, actually live. Our Rejuran treatment page describes it in exactly those terms: polynucleotide delivered directly into the dermal layer to stimulate collagen production.

That is also the line between a booster and a facial. A hydrating facial or a 'glass skin' routine works on the surface, and the dewy look usually fades within a few days. If you want to see how the surface steps and the injected ones fit together, I wrote about the boosters behind the dewy look separately. Here I stay with what's in the syringe.

The numbers on a booster plan, decoded

Six numbers tell you most of what a booster plan is trying to do: volume, depth, injection points, sessions, interval and time to visible change. Each one describes the job the product has been given.

So, is 2 mL enough? For a full-face quality treatment, a syringe of that size is the expected amount, spread thin on purpose. For a hollow under the eyes or a flat temple it was never meant to be enough, because that is a volume question. The U.S. Food and Drug Administration describes dermal fillers as devices injected under the skin to add volume and fullness, which is a different job.

Some products sold as boosters do contain hyaluronic acid. Rejuran HB combines PN with hyaluronic acid for hydration, according to our product page. That's a formulation choice for dry, barrier-damaged skin, and you can ask which version is on your plan.

Juvelook sits in a different family. It is usually grouped with collagen biostimulators, which prompt the skin to build collagen around the injected particles, and that mechanism is also why nodules are a known risk with this group. Rejuran works on repair through PN, so the two answer different questions. The VOS treatments overview, which lists Retizen among the collagen boosters, shows how the menu separates them. My broader guide to the types of Korean skin boosters sorts the families by ingredient.

How many sessions, and how far apart?

For Rejuran, the course on our treatment page is three sessions at one-month intervals, with regeneration effects described as lasting over six months. Other boosters follow their own schedules. The right number for you depends on where your skin starts, not on how many visits a plan happens to list.

The published evidence points the same way. A systematic review of polynucleotides in esthetic medicine in the Journal of Cosmetic Dermatology gathered studies that, for the most part, used a series of treatments rather than one injection. Single-session expectations are where a lot of disappointment starts.

For travellers the one-month interval is the number that shapes the plan. If you live in Singapore, Hong Kong or Tokyo, three visits a month apart can be three short trips. If you're flying in from London or Los Angeles, the realistic options are one session per visit with longer gaps, or a different treatment that does more in one sitting. A single session can still be booked, and the plan should then label it as one session of a three-session course.

When does the skin actually change?

Not on the first day. What you see in the mirror that evening is mostly water and the small swellings from each injection point. The change people have boosters for, smoother texture, softer fine lines, firmer skin, depends on fibroblast activity and new collagen, and that takes weeks.

Tissue repair of this kind is slow. In my experience the first session is often quiet and a difference is often noticed around the second session, though timing varies from face to face, and Rejuran i around the eyes follows its own pace.

Boosters also have limits. They don't change your skin colour, so 'how to get fair skin' isn't a booster question; if brightening is the goal, my piece on what glutathione injections can and cannot do covers that territory. And they don't lift a sagging jawline. Laxity of that kind is a job for energy-based devices or structural treatments, judged at an exam.

Side effects, risks and who should wait

Expect small bumps along the injection lines, pinpoint marks, redness and possibly bruising. These usually settle over a few days, though a bruise can take longer. Less common problems include infection, swelling that lasts, allergic reactions and, with some collagen-stimulating products, firm nodules under the skin.

Nodules are a recognised enough issue with certain biostimulators that our treatment menu includes a separate Juvelook Nodule Treatment. I mention it because it shows the menu plans for this complication; it says nothing about how often it happens.

People who should wait or talk it through first:

• Anyone with active acne, a cold sore or any infection in the area to be treated.
• Anyone pregnant or breastfeeding; elective injections are generally postponed.
• People on blood thinners, who bruise more. Never stop a prescribed medicine for a cosmetic treatment without asking your prescribing doctor.
• Anyone with a fish allergy. PN is purified from salmon or trout DNA, so this is a precaution to raise and discuss before a PN product is chosen.
• People with autoimmune conditions or a history of lumps after previous injections; bring the product names if you have them.
• Anyone with a wedding, a shoot or an important meeting within the next few days.

Worth knowing: VOS uses a 5μm ultra-fine filter syringe, designed to block micro-particles such as glass fragments from ampoules. It doesn't change what the product does. It addresses a contamination risk that few patients think to ask about.

If needles are the main reason you've avoided boosters, nitrous oxide sedation is available at VOS, and the clinic has recorded over 5,700 cases of it. You will still feel the injections, only less sharply.

How I approach a booster plan when your skin has been called difficult

At VOS, consultations are built around a skin analysis, including 3D skin analysis, before any product is chosen. For skin that someone has already called difficult, that step matters more than the brand on the syringe.

The reasoning then follows the problem. Thin, crepey skin with fine lines tends to be a case for a regenerative product placed shallow and spread wide. Dry, easily irritated skin may do better with a formulation that adds hydration. Rolling or boxcar acne scars usually need more than a booster can give on its own, and that conversation should happen before anyone books a syringe. A history of lumps after past injections means I want the product names before I suggest anything with particles in it.

The clinic's three principles are correct amount, genuine product and a specialist doing the injecting. In booster terms, the volume written on your plan is the volume that should go into your skin, and you are entitled to see the product.

Doctor's note

When someone tells me their dermatologist at home said boosters are mostly marketing, I don't argue. The word 'booster' covers products with very different ingredients and purposes, and some of the claims around them run ahead of the evidence. What I can do is show you which number on a plan does what, and tell you plainly when your skin needs a different tool or no injection at all. If your doctor at home said no because of an active skin condition, I would most likely say the same.

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Fitting a booster into a Seoul trip

Book the booster early in your stay, not the afternoon before a flight or a photographed event. Bumps from the injection points are usually most visible on the first day, and bruises, if they come, travel home with you.

A few practical facts shape the calendar. VOS is at 806 Eonju-ro in Gangnam, in front of Dosan Park, about an 11-minute walk from Exit 3 of Gangnam-gu Office Station on Line 7. The clinic is open Monday, Tuesday and Thursday from 10:00 to 19:00, Friday until 20:00 and Saturday from 10:00 to 16:00, and closed on Wednesdays, Sundays and public holidays. A Wednesday arrival with a Thursday appointment works; a window that only covers a Sunday doesn't.

If you're planning a three-session course across trips, keep the dates roughly a month apart. Keep any other treatment on the same face in mind too, because stacking several things in one visit changes the recovery picture.

Before you message us

Send two daylight photos of your face without makeup, one front and one side, plus the names and rough dates of any past injections.

If a dermatologist at home advised against boosters, add what they said and why. The photos and history help the in-person consultation start from your skin rather than from a generic plan, and the VOS Dermatology home page has the clinic's address and hours.

You can reach us on WhatsApp at https://wa.me/821096974628. Results, recovery and the number of sessions vary from person to person, and whether a skin booster suits you is decided at the in-person consultation.

Results, timing and recovery vary from person to person. This article is general information from VOS Dermatology Clinic and does not replace an in-person consultation. Any prices mentioned are from the clinic’s official price list (KRW, before VAT) and may change.