What are the common side effects of a skin booster?
Redness, swelling, small bumps, bruising and tenderness at the injection points. In the US trial of an HA booster, 199 treated people kept diaries for 30 days. Overall, 79.4% recorded some reaction: redness 68.8%, lumps and bumps 63.3%, swelling 61.3%, bruising 57.8%, pain 52.8%, tenderness 52.8%, firmness 47.2% and itching 25.1%. The FDA summary describes most as mild and lasting seven days or less, and says reactions after touch-up and repeat treatments were lower.
A systematic review of 13 studies of injected HA for skin quality found the same group: bruising, swelling and tenderness, typically lasting under two weeks, with no major safety issues. Investigators recorded a treatment-related adverse event in 6 of the 199 people (3.0%), most of them mild and resolved within 30 days. A European study of 131 people reported redness in 96.9% and swelling in 92.4%, most lasting one to seven days, which shows how much the figure depends on how closely reactions are recorded.
How long do bumps, redness and bruising last?
Redness, swelling and bruising mostly settle within the first week. Small bumps are the slowest to go. In the US trial, lumps or bumps were still recorded beyond 30 days in 8.0% of people (16 of 199), and three people (1.5%) had mild or moderate lumps that resolved 12 to 15 months after treatment.
The usual advice is to give bumps days and not to massage or press them unless told to. That advice is convention, since no study read compared handling. What the evidence supports is that most bumps settle, a minority linger, and a bump that grows or hardens after the first week is a reason to ask the doctor.
What rarer reactions can happen?
In the European study, treatment-related events were recorded in 16.0% (21 of 131): injection-site mass 9.2%, haemorrhage 3.1%, bruising 1.5%, haematoma 1.5%, redness 0.8%, a nodule 0.8% and a cold sore 0.8%. All were mild or moderate. One person had a nodule and redness of the neck beginning more than 90 days after treatment, which resolved with a course of oral steroid. The FDA summary also lists reports received after launch outside the US, in order of how often they were reported: inflammatory reaction, inflammatory nodule, loss of correction, allergic reaction, vascular occlusion, infection and abscess. Many resolved without treatment. Reports have no denominator, so they show what can happen and give no rate.
For HA fillers, a systematic review put delayed inflammatory reactions at 1.1% a year in prospective studies and possible delayed-type hypersensitivity at 0.06% a year, with only about 5% of reported cases proven genuine. Those are filler figures, and no equivalent booster figure was found. A consensus board describes late-onset reactions after HA fillers appearing 3 to 4 months after injection, and sometimes within 24 hours. It links them to the structure of the gel, to infection or dormant biofilm, and to the host immune system, for example active autoimmune disease or a viral illness. Late swelling and lumps after filler are covered in their own article, and the same logic applies to a booster.
Are polynucleotide skin boosters different?
The side-effect picture is similar and the evidence is smaller. A 2026 review of seven randomised trials (183 participants) reported no serious treatment-related adverse events. In the four skin-rejuvenation trials, local reactions were mostly mild and transient, and no infection, persistent redness, pigment change or scarring was reported. The reviewers note small samples, varied protocols and no standard formulations, so rarer events could be missed. What the evidence shows for polynucleotides goes through the trials, and how to check a product is KKM approved explains how to check the product in Malaysia.
Which aftercare rules have evidence, and which are convention?
Little aftercare advice has been tested. No trial or review read for this article compared make-up, sun, exercise or alcohol advice after a booster, so these are convention: reasonable, low-cost habits. The usual reasoning is that make-up and sun add irritation to skin that is already reacting, and that hard exercise, heat and alcohol widen blood vessels and may add to bruising or swelling in the first day or so. None of this is proven, and none of it is costly.
The pieces with firmer footing are about the procedure and not the days afterwards. A consensus on late reactions recommends a full medical history, informed consent, careful aseptic technique, a suitable product and depth, and education for the patient afterwards. For bruising, the filler trial excluded anticoagulants, aspirin, ibuprofen and supplements such as vitamin E, garlic and ginkgo from 10 days before to 3 days after injection. That was a study rule, and the trial did not compare outcomes with and without it, so the practical point is to tell the doctor every medicine and supplement taken, and to stop none of them without asking.
Who should wait, or not have a skin booster?
The trials give a list because they excluded these people, which means safety in them was not studied, and not that harm was shown. The US booster trial excluded anyone with an active inflammatory or infectious process on the face, such as acne or a cold sore, an abscess, or an unhealed wound; anyone with active autoimmune disease; anyone who was pregnant, breastfeeding or planning pregnancy; anyone with filler, laser, peel, light or radiofrequency treatment of the face in the previous 12 months; anyone allergic to lidocaine, HA or the bacterial proteins used to make it; and anyone prone to thick scars. The consensus on late reactions adds recent dental treatment and a current viral illness to the risk factors.
Those are study rules and consensus risk factors, and an individual decision is made by the doctor. Cold sores deserve a particular mention. The trial let people with recurrent oral herpes take preventive antiviral tablets for two days before treatment, and a booster around the mouth can set off a flare, which the article on cold sores before filler, peels and lasers explains. A flare after treatment that spreads, hurts or comes with a fever should be reported.
When should you call the doctor?
Call straight away, and go to an emergency department if the clinic cannot be reached, for sudden severe pain, skin that turns white, grey or blotchy, any change in vision, or redness that spreads hot and fast with fever or pus. The FDA summaries list vision impairment, blindness, stroke and skin necrosis among the possible effects of the category, and they are rare. They are also the reason these signs are not left to settle on their own.
Call within a day or two for swelling that grows after the first few days, a lump that enlarges or hardens, blisters, or a rash. Report a lump or redness that appears weeks or months later too. Infection and delayed inflammation need different treatment, and the consensus is explicit that infection needs drainage, culture and antibiotics and not a dissolving enzyme. At The Retreat Clinic, skinboosters, including polynucleotides, are offered after assessment, and that assessment is where the history above is useful to share. If the choice is between a booster and a filler, skin booster or filler: which does what sets out the difference, and the skinbooster page describes the treatment.
