Rejuran Side Effects and Aftercare: Bumps, Bruising, Allergy and What’s Normal

Rejuran is generally well tolerated, and most side effects are mild and settle within a few days. However, the small bumps that appear straight after treatment can be surprising if you do not expect them. This guide explains which Rejuran side effects are normal, how long they usually last, which signs need a doctor’s review and how to look after your skin afterwards. If you are considering Rejuran and want a doctor to check whether it suits you, contact CLEO Clinic.

Why Rejuran Causes Side Effects

Rejuran is a polynucleotide (PN) skin booster made from purified salmon DNA. Usually, it is injected in many tiny amounts into the upper layer of the skin. Because each injection creates a small pocket of product, the skin reacts with temporary bumps, redness and mild swelling. In other words, most early side effects come from the injections themselves rather than from the product. For an overview of the treatment, types and cost, see our Rejuran treatment in KL page.

Common Side Effects: What’s Normal

Small Bumps (Wheals)

Small raised bumps at each injection point are the most noticeable side effect. In fact, they are expected, especially when Rejuran is injected by hand. Usually, they flatten within 24 to 72 hours as the product spreads into the skin. Importantly, you should not press, massage or squeeze them, as this can cause irritation.

Redness

The treated area often looks pink or red straight after treatment. Typically, redness fades within a few hours to a day. In addition, people with sensitive or rosacea-prone skin may stay red slightly longer.

Mild Swelling

Some mild puffiness is common, particularly around the eyes and on thinner skin. As a result, swelling is often more noticeable the morning after treatment and then settles over one to two days.

Bruising

Small bruises can appear where a needle has passed a tiny blood vessel. Notably, they are more likely under the eyes, where the skin is thin, and in people who take blood thinners or certain supplements. Bruises usually fade within about a week, and makeup can cover them once the skin has settled.

Tenderness and Discomfort

The skin may feel tender or slightly sore for a day or two. Numbing cream is used before treatment, so most people find the injections themselves tolerable. If this is your first session, our guide on what to expect at your first Rejuran treatment explains the visit step by step.

How Long Do Rejuran Side Effects Last?

For this reason, it is wise to avoid booking Rejuran right before an important event. Our guide on avoiding skin booster injections before events explains how far ahead to plan.

Less Common Side Effects

Allergic Reaction

Because Rejuran is derived from salmon, people with a fish or salmon allergy should not have it. Allergic reactions are uncommon, but signs can include itching, hives or spreading swelling. Seek urgent medical help if you notice swelling of the lips, tongue or throat, or any difficulty breathing.

Infection

In practice, infection is uncommon when treatment is done in a clean clinical setting and aftercare is followed. Still, any injection breaks the skin, so infection is possible. Contact your doctor if you notice increasing pain, warmth, spreading redness, pus or fever after treatment.

Cold Sore Flare

Injections around the mouth can trigger a cold sore in people who get them. Therefore, tell your doctor if you have a history of cold sores, as preventive medicine may be offered.

Lumps That Do Not Settle

Bumps that persist beyond a few days are uncommon. A 2026 expert review of polynucleotides in Clinical, Cosmetic and Investigational Dermatology reported that granulomas and nodules had not been described in the published literature to date (Rho et al., 2026). Nevertheless, the authors noted that long-term safety data are still limited, so any lump that persists should be reviewed by your doctor.

Who Has a Higher Risk of Side Effects?

Some people are more likely to bruise or react. For example, those taking blood thinners, aspirin or supplements such as fish oil may bruise more easily. However, never stop a prescribed medicine without speaking to your doctor first. Similarly, people with sensitive skin or an active flare of eczema or rosacea may react more. If you have sensitive skin, our guide to kulit sensitif (Bahasa Malaysia) explains common triggers. Rejuran is also not given during pregnancy or breastfeeding, or where there is an active skin infection in the area.

Rejuran Aftercare: What to Do

The First 24 Hours

First, keep your hands off the treated area and let the bumps settle on their own. Next, wash your face gently with a mild cleanser and lukewarm water. Avoid makeup for about 24 hours, so the tiny injection points can close. In addition, sleeping with your head slightly raised on the first night can help reduce puffiness, especially after under-eye treatment.

The First Two Days

For about two days, avoid saunas, steam rooms, hot yoga and heavy exercise, as heat and sweating can increase redness and swelling. Likewise, pause strong skincare such as retinoids, exfoliating acids and scrubs until your skin has settled. Facials, massages and other in-clinic treatments on the same area should also wait until your doctor advises.

Ongoing Care

Use a broad-spectrum sunscreen every day, as treated skin can be more sensitive to the sun. Meanwhile, keep your routine simple with a gentle moisturiser. Some people also use the home-use Rejuran ampoule as part of their routine, which our guide to the Rejuran ampoule explains. Even so, it is a skincare product and does not replace injections.

When to Contact Your Doctor

Most side effects are mild and expected. However, contact your doctor if bumps or swelling last longer than a week, if bruising is severe, or if you notice signs of infection. Seek urgent help straight away for any signs of a serious allergic reaction, such as facial or throat swelling or difficulty breathing.

Side Effects by Rejuran Type

Side effects are similar across Rejuran types, although a few differences are worth knowing. Rejuran I (Eye) is placed in thinner skin, so bruising and swelling are more common under the eyes. Meanwhile, Rejuran S is a thicker formula used for scars, so bumps may take slightly longer to settle. Finally, Rejuran HB contains a local anaesthetic, which many people find more comfortable. To compare the two most common types, read Rejuran Healer vs HB, or learn about Rejuran S for acne scars.

Will Side Effects Affect My Results?

No. Normal bumps, redness and bruising do not affect the final result. In fact, results build gradually over several weeks after the bumps have settled. For a realistic timeline, read our guide to Rejuran before and after results.

How to Lower Your Risk of Side Effects

Choosing a doctor-led clinic and a genuine product are the most important steps. In Malaysia, injectable Rejuran is a medical device, so you can check its registration with the Medical Device Authority (MDA). Also, ask to see the sealed box, batch number and expiry date before treatment. Finally, tell your doctor about allergies, medicines, supplements and any history of cold sores. If you are unsure whether a PN or PDRN treatment is right for you, our guide to salmon DNA (PN) vs PDRN explains the options.

Frequently Asked Questions

Are bumps after Rejuran normal?

Yes. Small bumps are expected and usually flatten within 24 to 72 hours. Avoid pressing or massaging them.

How long does bruising last after Rejuran?

Bruises usually fade within about a week. They are more common under the eyes and in people who bruise easily.

Can I wear makeup after Rejuran?

Usually, you can wear makeup after about 24 hours, once the injection points have closed. Your doctor may give specific advice for your skin.

Can I exercise after Rejuran?

Light activity is fine. However, avoid heavy exercise, saunas and hot yoga for about two days.

Can I have Rejuran if I am allergic to fish?

No. Because Rejuran is made from salmon DNA, it is not suitable for people with a fish or salmon allergy.

Book a Rejuran Consultation

Most Rejuran side effects are mild, temporary and easy to manage with good aftercare. To learn more about skin boosters in general, see our skin booster treatments page. To find out whether Rejuran suits your skin, book a consultation with CLEO Clinic.