XERF Side Effects: When Do They Appear, and How Long Is Normal?
Most of the questions we get after a radiofrequency treatment arrive the same evening or the next morning, and they are all the same question — is this normal? The useful way to answer it is not a list of possible side effects but a timeline, because the reactions reported with radiofrequency appear at different times. Some are visible within the hour, some after three days, and one of them only shows up one to four months later. This column is that timeline, with the source of every number attached.
The short answer
The common reactions after XERF are redness and a hot, tender feeling, and they usually settle within the first few days. Blistering is uncommon, but when it happens it is generally visible within 72 hours. Fat atrophy — a pressed-in hollow — runs the other way and appears at one to four months. The figures with denominators below come from high-energy single-pass monopolar devices of the early 2000s; the three human studies of XERF itself have no control group and are too small to measure the frequency of a rare event. Miso Clinic in Daegu (4F Bombom Building, 125 Dongdeok-ro, Jung-gu, Daegu, South Korea; +82-53-428-2700) treats with XERF and explains both the possible reactions and when to call before the first session.
Why read side effects as a timeline?
Search results on this topic usually present the reactions as one undifferentiated list. In the clinic, though, which day you are on decides almost the whole judgement. Redness on the evening of the treatment and redness a month later do not mean the same thing, and a blister on day three has a different cause from a hollow at week eight.
So the sections below are ordered by time rather than by severity. One caveat first: the figures that have a denominator come from older monopolar devices, not from XERF. They are the best available description of what can happen, not a prediction of how often it will.
The first 72 hours — redness and heat
- ImmediatelyRedness, warm skinRedness in 36.0% immediately in a periorbital series of 86 subjects. Heat was just delivered into the tissue, so this is expected.
- HoursBurning feeling, mild swellingUsually settles with cooling.
- 72 hoursRedness down to 16.7%In the same series redness fell to less than half by day three, and to 3.9% at one month.
Blistering in that series was 2.3% immediately and 3.8% within 72 hours — which is the practical point: if a blister is going to appear, it generally appears within three days. Second-degree burns were reported in 21 of 5,858 treatments (0.36%), and that number belongs to the 2002 high-energy single-pass technique. It is not a current incidence.
Two trials of non-invasive radiofrequency advised immediate return to normal activity and usual cosmetics, with zero cases of pigmentation. Neither trial used XERF.
Day three to two weeks — the settling window
What can still be present in this window is faint redness, tenderness on pressure, and bruising. If a blister or a crust formed, this is when it heals. Leaving the crust alone is the part that matters for avoiding pigmentation.
What should not happen in this window is new pain, a red area that keeps enlarging, or anything purulent. Those are not part of the course; they are reasons to call, and they are listed below.
Patients on isotretinoin often ask whether the treatment must be postponed. A 2017 review of about 27 studies concluded that no waiting period is needed before procedures including radiofrequency. We still ask you to tell us what you are taking before the session.
One to four months — what shows up late
The latest reaction reported with radiofrequency is fat atrophy: heat delivered too far into the fat layer, leaving that area looking pressed in. In the published series it appeared at one to four months (mean two months), at about 4 per 10,000 treatments.
The timing is the reason this matters. A session that went well on the day is not yet a finished result, and conversely a hollow noticed two months later is easy to mistake for ageing or weight change. That is why we look at the result at two to three months before deciding on another session.
Fat atrophy is difficult to reverse, so the weight sits on prevention: output and pass count set per area, and no repeated stacking over the same spot.
Why heavy anaesthesia raises the risk
In radiofrequency, pain is not only discomfort — it is information. If a spot becomes too hot, you say so, and the output or the pass stops there. The series that reported fat atrophy also noted that heavy anaesthesia blocks this pain feedback.
Asking not to feel pain is reasonable. But reducing surface sensation with a numbing cream and removing the ability to feel heat are two different things. Telling us the moment a spot feels too hot is part of the safety design, not an interruption of it.
How far does the evidence on XERF itself go?
Three human studies of XERF can be identified: 20 subjects with one session over 12 weeks, 39 subjects with two sessions over 90 days (manufacturer support), and a retrospective series of 16 subjects with one session over three months. None of the three has a control group, and at that size the frequency of a rare adverse event cannot be measured.
No direct device-to-device comparison has been identified either; a 2026 systematic review (15 studies · 1,230 people, one randomised trial) states this explicitly. So there is no basis for saying that XERF has fewer side effects than another device — in either direction.
In Korea the device is licensed in the general electrosurgical class. A number such as the one printed on promotional material is usually an advertising pre-review number rather than a product licence number; the two are different procedures.
Call us if you see any of these
- Redness or swelling that grows instead of fading as days pass
- A wide blister, or anything that turns yellow and purulent
- Pain that is new and persistent in one area
- An area that looks pressed in weeks later
- Numbness that does not come back
The number is +82-53-428-2700. A photograph helps us read the course. Asking once is better than waiting it out.
Summary — what is established and what is not
Established
- Redness after radiofrequency was reported as falling over time (36.0% immediately → 16.7% at 72 hours → 3.9% at one month).
- Blistering, where it occurred, was generally visible within 72 hours (2.3% immediately · 3.8% within 72 hours).
- Fat atrophy appeared at one to four months (mean two months), at about 4 per 10,000 treatments.
- The published series notes that heavy anaesthesia blocks pain feedback.
- A review concluded that no waiting period is needed on isotretinoin before radiofrequency.
Not established
- The frequency of any adverse event with XERF — the three human studies have no control group and are too small.
- Whether the figures above transfer to XERF — they come from older high-energy devices.
- Any comparison of adverse events between radiofrequency devices — no direct comparison has been identified.
- How much a given output or pass count reduces the risk of fat atrophy — no human comparison exists.
XERF side effects: frequently asked questions
My face is still red the day after XERF. Is that normal?
Redness is a common reaction to heat delivered into the skin. In the radiofrequency series it had fallen to less than half of the immediate figure by day three. If it is fading, we read it as the normal course; if it is spreading or the pain is increasing, please call.
Once a few days have passed, is it all over?
No. Redness and blistering show within days, but fat atrophy appeared at one to four months. That is why we look at the result again at two to three months.
Can XERF cause a burn?
Blistering and second-degree burns are reported across radiofrequency treatment. The published proportions, however, belong to high-energy single-pass devices of the early 2000s and are not a current incidence. For XERF itself there is no data from which to calculate a frequency.
Can I have more numbing cream?
Reducing surface pain and removing the sense of heat are different things. Heat is the signal used to set output, so please tell us as soon as a spot feels too hot.
Does XERF have fewer side effects than other lifting devices?
There is no basis for that claim. A 2026 systematic review states that no direct comparison between radiofrequency devices has been identified.
I am taking isotretinoin. Can I still have the treatment?
A review of about 27 studies concluded that no waiting period is needed before radiofrequency. Please tell us what you are taking before the session.
Read next
Product pages
Product pages: XERF — mechanism, handpieces, evidence
Who wrote this
Written and reviewed by Lee Chi-Hak, MD, director of Miso Clinic, Daegu. The treatment standards and injection design set out here are the ones we use in practice.
| Medical director | Lee Chi-Hak, MD |
|---|---|
| Address | 4F Bombom Building, 125 Dongdeok-ro, Jung-gu, Daegu, South Korea · Exit 1, Kyungpook National University Hospital Station |
| Phone | +82-53-428-2700 |
| Hours | Weekdays 11:00–19:00 (lunch 13:00–14:00) / Saturday 10:00–16:00 (no lunch break) / Closed Sundays and public holidays |
| Columns | All clinical columns |
| Reference library | All booster and device references |
References
- What the XERF data can and cannot measure — the three human studies have 20, 39 and 16 participants and no control group. A sample of that size cannot measure the frequency of a rare adverse event. Every figure with a denominator below comes from older monopolar RF devices and is not an incidence for XERF.
- Timing and frequency of RF adverse events (older device) — Fitzpatrick R et al., Lasers Surg Med 2003;33:232–242 (86 subjects): blistering 2.3% immediately · 3.8% within 72 hours; second-degree burns in 21 of 5,858 treatments (0.36%) — figures for the 2002 high-energy single-pass technique, not a current incidence.
- Course of redness — Fitzpatrick 2003 (periorbital, 86 subjects): redness 36.0% immediately → 16.7% at 72 hours → 3.9% at one month. Two clinical trials of non-invasive RF (Wanitphakdeedecha 2022 · Imaizumi 2026) advised immediate return to normal activity and usual cosmetics, with zero cases of pigmentation.
- Fat atrophy — Narins RS et al., Dermatol Surg 2006;32:115–124. Appears at 1–4 months (mean 2 months), about 4 per 10,000 treatments. Notes that heavy anaesthesia blocks pain feedback.
- Three XERF human studies — Hwang JK, Medical Lasers 2025;14(1):23–30 (20 subjects · one session · 12 weeks) · Weiss RA et al., Cureus 2026;18(3):e104546, PMID 41930066 (39 subjects · two sessions · 90 days, manufacturer support) · Erlich G et al., Lasers Med Sci 2026;41(1), PMID 42611100 (retrospective, 16 subjects · one session · 3 months). None of the three has a control group.
- XERF specifications — Lutronic published data: monopolar, 6.78 MHz plus 2 MHz, handpieces i05 (5×10 mm · 400 shots) · i10 (10×10 mm · 300 shots) · E40 (20×20 mm · 600 shots) · E60 (20×30 mm · 600 shots). The shot count is sealed into the tip; it is not a recommendation for how many shots a face needs.
- Evidence for comparing devices — Aesthetic Surgery Journal Open Forum 2026 systematic review (15 studies · 1,230 people, one randomised trial). Heterogeneity prevented meta-analysis and the review states that no direct device-to-device comparison was identified.
- Isotretinoin and procedures — Mysore V et al., J Cutan Aesthet Surg 2017;10:186–194 (review of about 27 studies): concluded that no waiting period is needed before procedures including radiofrequency.
- Licence numbers and advertising review numbers — a Korean MFDS device licence and a medical advertising pre-review are two different procedures. The number printed on promotional material is usually the advertising review number, not the product licence number.
- Medical advertising law — Medical Service Act of Korea, Article 56(2), which prohibits testimonial advertising, comparison with other clinics, superlative claims and advertising that guarantees or implies a guaranteed treatment effect.
- Miso Clinic practice guidance — indication criteria, site-by-site design, and the explanation and consent procedure. This is the source for every sentence marked as clinical judgement.
Everything in this column is general information and does not replace medical diagnosis or treatment. Effects and side effects vary with individual skin condition, age and underlying illness, and the same result is not guaranteed for everyone. Any decision to proceed should be made in an in-person consultation with a physician.