UltraShape breaks fat cells open mechanically. CoolSculpting freezes them until they die. UltraShape sends focused ultrasound into the tissue. That energy makes the tissue move at a small scale, and the movement bursts the walls of fat cells. CoolSculpting cools the tissue for 35 to 60 minutes, until the fat cells are hurt badly enough to shut down and die. In both cases the body clears the debris over the following weeks.
The everyday difference is that UltraShape has no cooling, no vacuum and, in the published trial, no pain and no bruising at all. In a split-body thigh study of 14 women, every person reported zero out of ten on the pain scale. No swelling was recorded, and no adverse events happened. Mild redness was universal. CoolSculpting pulls tissue into a cup and freezes it. That leaves the area numb and firm for days to weeks.
But they are cleared on different endpoints, and that is the part most comparisons skip. UltraShape's original and central claim is "non-invasive reduction in abdominal circumference". That is a tape measure. CoolSculpting's claim is cold-assisted lipolysis of named fat bulges, with fat-layer thickness as the measured secondary endpoint. Circumference, fat-layer thickness, fat volume and weight are four different things. A result on one does not convert into a result on another.
The FDA class it sits in is defined as focused ultrasound producing "localized, mechanical motion within tissues and cells... for mechanical cellular membrane disruption intended for non-invasive aesthetic use".
It was authorised through a De Novo request, DEN090002, decided 24 August 2010. That request created the FDA device category for cryolipolysis.
It is not a heating treatment. That is why there is no cooling plate, and no need to protect the skin from heat.
Fat cells are more easily harmed by cold than skin, nerve, vessel or muscle, because of the lipid they hold. Pivotal settings in the FDA files include minus 10 degrees Celsius for 60 minutes, and minus 11 degrees for 35 minutes.
K141708, cleared 6 October 2014, is abdominal circumference alone. K161952, from November 2016, adds lipolysis wording and the flanks. K162163, later that month, and K170370 in May 2017 read "non-invasive reduction in abdominal circumference and fat reduction in the flanks and thighs". A 510(k) clearance means the FDA agreed the device is much the same as one already on the market. It is not a finding that the device works.
CoolSculpting Elite, K212707, cleared 5 November 2021. Under the chin and jaw are cleared separately, up to a body mass index of 46.2.
In the split-body thigh trial at 16 weeks, the treated thigh was 2.8 cm smaller at the midline than the untreated one. Caliper fat thickness was down 22.2 per cent. Ultrasound fat thickness was down 19.2 per cent, or 4.03 mm.
Blinded photo picking is the main endpoint in most CoolSculpting clearances. It is a spot-the-difference test, not a measurement of fat. The FDA's own pooled review inside K160259 put mean ultrasound reduction at 20.6 per cent, across a range of 10.3 to 25.5 per cent. An independent randomised split-body trial found about 14 per cent.
The transducer is moved across a mapped area rather than clamped onto a bulge.
The vacuum cup needs tissue to draw in.
Mild redness happened in everyone. There is no cooling, no suction, and no bruising reported in that study.
Delayed pain arriving a few days later is common. One review of 554 procedures found it lasted 3 to 11 days. Numbness beyond 12 weeks happened in 4 of 30 patients in the FDA-reviewed arm study.
Results in the trial were checked at 4, 8 and 16 weeks.
In the largest real-world review, covering 3,262 patients, the median was 4 cycles and 1 session per patient.
The RealSelf page for UltraShape carries an 83 per cent "Worth It" rating from 26 reviewers, last updated 16 August 2023. It publishes no cost figure at all. There is no citable national average for it.
It is priced per cycle rather than per session, which is why the totals scatter.
Wilkerson and colleagues in 2018 ran the cleanest design in this comparison: It was a split-body study: one thigh was treated, and the other served as that person's own control. There were fourteen women, aged 33 to 60, with a body mass index of 18 to 30. Each had three treatments two weeks apart, and was followed to 16 weeks. Against their own untreated thigh, the treated side was 2.8 cm smaller in circumference. It was 22.2 per cent thinner by caliper and 19.2 per cent thinner on ultrasound. Ninety per cent said they were satisfied.
Split-body designs are the strongest thing this field produces: They remove the biggest confounder, which is the person losing or gaining weight during the study. What the trial cannot tell you is how the device performs on an abdomen. That is the area its central clearance names. Nor can it tell you how the device compares against a sham rather than against no treatment. The paper describes the device as an FDA-cleared Syneron Candela system. Whether any of the authors had a financial relationship with the company is not something that could be confirmed.
This is worth separating out. UltraShape's core clearance is written in the language of circumference, and its trial reports both.
A tape measure around an abdomen includes skin, fat, muscle, gut contents and fluid: It also changes across a day, with posture, breath, meals and time. Nobody in this literature has published how much a body-contouring circumference measurement moves on its own. So there is no published noise floor to compare a 2 to 3 cm result against. Fat-layer thickness is a different quantity. It is one tissue, at one point, measured through the skin on one axis by ultrasound. That is reliable when the protocol is standardised, and it is rarely reported in a standardised way here.
Neither of them is fat volume, and neither is weight. When a clinic puts "2.8 cm" next to "25 per cent", it is placing two unrelated measurements side by side.
The FDA states it on its own page about non-invasive body contouring, last updated 15 October 2025: "Non-invasive body contouring does not treat obesity or improve your health. It will not result in weight loss or contribute to the health benefits associated with weight loss." CoolSculpting's manufacturer says the same thing in its own safety information.
That framing comes from the regulator and from the manufacturers. No professional society has issued a position statement to that effect. The body mass index limits inside the CoolSculpting clearance are ceilings on who may be treated. They are not something the treatment is meant to change.
Ask which UltraShape model the clinic has, and which areas its clearance covers: The 2014 clearance is abdominal circumference only. Flanks and thighs came later, on later models. If you are being offered a treatment on an area the machine in that room is not cleared for, you should at least know that is what is happening.
For CoolSculpting, three blood disorders rule it out completely: They are cryoglobulinemia, cold agglutinin disease and paroxysmal cold hemoglobinuria. In all three, blood reacts badly to cold. Disclose in advance any cold urticaria, Raynaud's disease, pernio or chilblains. Do the same for any bleeding disorder or blood thinner, reduced feeling or poor circulation in the area, and any hernia in or next to the treatment site. Hernia is on the FDA's risk list for this class and on the maker's precaution list. It is also the item most often skipped over.
Fever or chills after treatment
Redness around a treated area that is visibly spreading hour by hour
Pus or discharge from treated skin
These are signs of a spreading infection and need urgent care the same day.
A firm, well-defined lump appears in a CoolSculpting-treated area two to six months later, above all if it matches the shape of the applicator
An area starts to look hollow, dented or uneven next to the other side
Numbness in a cooled area is still there after about three months
Pain in a treated area is rising rather than settling after the first two weeks
The skin over a treated area darkens a lot over the following weeks
Blistering, crusting or an open area appears on treated skin
The first item on that list is paradoxical adipose hyperplasia. It is a rare complication of cryolipolysis in which the treated area gets bigger instead of smaller. It does not clear up on its own, and correction is surgical. Published incidence estimates disagree by about a hundredfold, largely because some count cycles and some count patients.
Focused ultrasound is not implicated in this. What has been reported for focused ultrasound devices in the FDA's post-market database is unintended fat loss and surface irregularity. That database has no denominator. Its counts are counts of reports, not rates, and they cannot be turned into a percentage of patients.