Rejuran: effects, pain, HB, and downtime explained

Rejuran is based on polynucleotides (PN), purified DNA-derived chains obtained from salmon. It does not inject living cells or collagen itself. PN can retain water and form a gel; the intended changes include hydration, skin texture, and fine lines.

PN and PDRN are related DNA-derived materials, but they are not interchangeable products. PN forms relatively long, viscous chains; PDRN consists of shorter DNA fragments. Product classification and approved uses also differ.

In a split-face study of 27 people, PN and non-cross-linked hyaluronic acid were injected around the eyes three times, two weeks apart. Hydration improvement was greater on the PN side, but improvement declined over time in both groups. Other human studies have reported changes in fine lines and texture; uncontrolled studies cannot establish how much change is due to PN alone.

A 2025 systematic review assessed nine studies involving 219 participants and rated the evidence as low or moderate in quality. Products, treatment sites, and study methods differed. Rejuran is an option for fine lines and skin quality, rather than a treatment that resolves every skin concern. Improvement in a pore measurement does not mean permanent pore removal, and deep scars or sagging contours need a different assessment.

Laboratory and animal findings about collagen production or skin-barrier recovery suggest possible mechanisms. They do not by themselves prove long-term benefit from injecting Rejuran into human skin. Holding water and strengthening the outer skin barrier are related but different effects.

Pain comes from the needle and the pressure or irritation of the formulation entering tissue. Repeated injections, treatment site, injection volume and technique, anaesthesia, and individual sensitivity all affect the experience. More pain is not evidence of a better treatment.

The HB formulation combines PN with hyaluronic acid and lidocaine, a local anaesthetic. Reduced pain does not mean reduced efficacy. HB can still hurt; it should not be described as a completely painless procedure. Tell the clinician about diagnosed lidocaine allergy or a previous reaction to dental or other local anaesthesia.

Small raised bumps can appear when a little product is injected into the dermis. Their size depends on the formulation, injection volume, and depth. They often settle within one to three days, although some last longer.

Bumps can give the injector a clue about placement, but cannot confirm that every dose and depth was appropriate. Larger or longer-lasting bumps do not promise better results, and a technique that creates fewer visible bumps can still improve skin. Ask the clinic to assess lumps that remain hard or redness and pain that worsen.

Some product guidance describes an initial course of three or four sessions, three to four weeks apart, followed by maintenance around six months later. Research schedules differ. Neither three-month nor six-month maintenance is a universal rule, and a retreatment interval is not an expiry date for all benefit. Reassess the changes that remain and whether another session is needed.

Redness and bumps often improve within one to three days. Needle marks can remain for several days, and bruises can be visible for one to two weeks. Returning to daily activities and having no visible marks are different milestones. The original suggests allowing at least a week before an important event, or about two weeks when planning for bruising; this is a planning margin, not a recovery guarantee.

Pain, swelling, bruising, itching, and injection marks can occur. Breathing difficulty or throat swelling after treatment needs immediate medical attention; in Korea, call 119 if you are outside the clinic. Discuss your skin concerns, allergy history, pain tolerance, and travel schedule before choosing a product and treatment plan.