Problems after Cryolipolysis: Paradoxical Fat Increase, Delayed-Onset Pain, Numbness and Frostbite

What problems can occur after cryolipolysis?

Cryolipolysis is based on cooling the fat tissue beneath the skin in a controlled way with the help of an applicator. For how the procedure is done, who it suits and how much change can be expected, see our article “Cryolipolysis (Fat Reduction by Cooling)”. This article focuses on the problems that can arise after the procedure.

In a systematic review examining side effects, the most commonly reported effects are redness, numbness or tingling, bruising and swelling in the treatment area; most of these are mild and pass quickly. The same review lists severe or prolonged pain, altered sensation, darkening of the skin, rarely muscle weakness, and paradoxical fat increase among the more serious problems. The U.S. Food and Drug Administration (FDA) also emphasises that cryolipolysis is a medical procedure with benefits and risks.

How long do redness, bruising and swelling last?

After the applicator is removed, the area may look cold, firm and red for a while. Bruising, swelling and tenderness to touch due to the pulling effect of vacuum applicators are common and mostly lessen within days, sometimes within a week or two. For the course of bruising, you can look at our article “Bruising and Swelling”.

The FDA states that small, temporary firm areas that can be felt but not seen from outside may also form in the area. Redness, pain, blistering or a dark change in skin colour that increases as the days go by, on the other hand, is outside the expected course.

What is paradoxical adipose hyperplasia (paradoxical fat increase)?

Paradoxical adipose hyperplasia is growth, rather than shrinkage, of the fat tissue in the treated area. A firm, raised, well-defined swelling forms in the area, often resembling the shape of the applicator used. It usually causes no pain or is only mildly tender. This problem is specific to fat reduction by cooling; why it occurs is not yet known.

An important feature is that it is not noticed straight away. The area may first shrink as expected and then begin to grow. According to the FDA, this condition has been reported two to five months after the procedure. For this reason, if months after the procedure you notice a fullness that is growing in the treatment area, show it to your physician before putting it down to weight gain.

The FDA states that paradoxical fat increase does not go away by itself and that surgery may be needed to remove the visible swelling. One of the publications that first described this condition also reported that there was no evidence of it regressing spontaneously. In practice, correction is mostly carried out with surgical methods such as liposuction; applying cryolipolysis to the same area again does not solve the problem. Which method is appropriate, and when, is decided by the physician who examines you.

How often does paradoxical fat increase occur?

It is not possible to give a precise rate, because estimates vary markedly from study to study. In the first reports, published in 2014, the frequency was calculated at about one in twenty thousand treatments. In a study examining data from eight centres in Canada, however, rates ranging from 0.05 to 0.39 per cent were found depending on the centre; it was reported that the frequency fell markedly after the move to newer-generation applicators.

In a meta-analysis published in 2025 bringing together 28 studies, the frequency per patient was calculated at about 0.2 per cent, that is, roughly one in 450 people. The researchers stated that the certainty of the evidence on which this estimate rests is low, that in most studies the follow-up period was too short to capture this condition, and that the true frequency appears higher than manufacturers’ data suggest. In some studies it has been reported more often in men; however, in the same meta-analysis the difference between the sexes was not found to be statistically significant.

In short, this is a rare risk but one that cannot be ignored, and it needs to be explained to you clearly before the procedure.

Is pain that starts days later normal?

In some people, a burning, stinging or aching pain may begin a few days after the procedure, especially in the abdominal area; it may be more noticeable at night. In a study examining the records of 125 patients, this delayed-onset pain occurred mostly in young women treated on the abdomen, lasted 3 to 11 days and passed without leaving any problem. In some people the pain may last longer.

This pain is usually not a sign of anything dangerous; however, it can affect daily life and sleep. Ask your physician which painkiller you can use. If the pain is steadily increasing, or is accompanied by fever, redness, blistering or a new swelling in the abdomen, see a physician without waiting.

How long do numbness and changes in sensation last?

Cold temporarily affects the fine sensory nerves in the skin. For this reason numbness, tingling, itching or an altered sensation to touch are common in the treatment area. The FDA states that numbness may last a few weeks; in some people it may last longer, and it usually improves by itself.

Numb skin cannot sense heat and cold well. Applying a hot-water bottle, a heating pad or ice to the area during this period can cause burns that go unnoticed. After treatments under the chin, the FDA states that a temporary change in lip or tongue movement due to nerve effects and a temporary feeling of fullness at the back of the throat have been reported. Temporary muscle weakness after treatment of the arm has also been reported rarely in the literature. Any new loss of strength or asymmetry of movement should be reported to a physician the same day.

How can frostbite (cold injury) be recognised?

Cryolipolysis devices monitor the temperature continuously to protect the skin, and a protective gel pad is placed between the skin and the applicator. When this protection is inadequate, when the pad is not positioned correctly or when unregulated devices are used, the skin can freeze. The FDA states that frostbite may be superficial or may be severe enough to involve all the layers of the skin.

• Burning and pain that does not pass after the procedure and steadily increases
• Blistering (bullae) or a wet, oozing area
• A dark red, purple, grey or black change in skin colour
• An area that hardens and has lost all sensation; a crust or an open wound in the following days

In one published case, after cryolipolysis carried out at a non-medical beauty centre, full-thickness frostbite developed over a wide area of the abdominal skin; the patient had to be admitted to hospital and undergo more than one operation. Attempts at home with ice, cold packs or home devices carry the same risk. The FDA states that the safety and effectiveness of fat-freezing methods sold without a prescription or used at home have not been demonstrated. For devices of unknown origin, see our article “Counterfeit Products and Unlicensed Treatments”.

Who should not have cryolipolysis?

In some conditions the body reacts to cold in an abnormal and harmful way. The FDA states that the procedure should not be carried out in the following conditions involving sensitivity to cold:

• Cryoglobulinaemia: a condition in which the blood contains proteins that precipitate in the cold, and which can lead to blocked vessels and tissue damage
• Cold agglutinin disease: a blood disorder in which red blood cells clump together and break down in the cold
• Paroxysmal cold haemoglobinuria: a rare blood disorder in which red blood cells break down on exposure to cold and the urine becomes dark
• Cold urticaria: hives appearing after contact with cold; in severe cases a widespread allergic reaction can develop
• Circulatory reactions such as Raynaud’s disease and cold-related purplish discolouration of the fingers or toes (chilblains)
• Impaired circulation in the treatment area

The FDA also states that hernias have been reported in the treatment area after cryolipolysis, and that the procedure should not be carried out over or near an existing hernia, a surgical scar or weak areas such as separation of the abdominal muscles after pregnancy. If you do not know whether you have one of these conditions, tell your physician whether you have had hives in the cold, whitening or purplish discolouration of the fingers, or darkening of the colour of your urine.

Normal, consult a physician, or an emergency?

What can your physician do?

The physician first examines the area and asks when the procedure was done, with which device and applicator, and in how many sessions. Depending on the situation, the following approaches may be considered:

• For expected side effects: monitoring and aftercare advice; for delayed-onset pain, the pain treatment the physician considers appropriate.
• For frostbite: wound care, close follow-up for infection and, if necessary, assessment by plastic surgery or a burns centre.
• For a growing firm swelling: examination and, if necessary, imaging such as ultrasound to distinguish paradoxical fat increase from other causes (a hernia, a collection of blood, weight gain).
• Where paradoxical fat increase is diagnosed: discussion of the options for surgical correction and their timing; referral to the relevant surgical specialty.
• For prolonged changes in sensation or loss of strength: assessment together with relevant specialties such as neurology.
• For symptoms such as dark urine, jaundice or widespread hives: blood tests for a cold-related condition and referral to the relevant specialty.

For the general steps you can follow when you have a problem, our article “What Should You Do If a Complication Occurs after an Aesthetic Treatment” may be a useful guide.

What can you do at home, and what should you not do?

• Follow the aftercare instructions your physician gives you; choose loose, comfortable clothing.
• If you need a painkiller, ask your physician which medicine you can use.
• Keep photographs of the treatment area from before and after the procedure; taking a photograph from the same angle once a month for several months makes it easier to notice changes that appear late.
• Note the date of the procedure, where it was done and, if you know, the type of device.

Do not do the following:

• Do not apply a hot-water bottle, a heating pad or ice to the numb area.
• Do not burst blistered areas or pick off crusts; do not apply medicated cream on your own.
• Do not have cryolipolysis again, or treatment with another device, on the same area to correct a growing swelling; the cause needs to be understood first.
• Do not simply put a growing fullness down to weight gain and wait for months.
• Do not try to freeze fat at home with ice, cold packs or home devices.

To reduce the risk

• Have your suitability assessed by a physician; describe any cold-related complaints, blood disorders, and your history of hernias and surgery.
• Ask for the risk of paradoxical fat increase, and the course that would be followed if it developed, to be explained to you clearly before the procedure and to be included in the consent form.
• Ask which device will be used, whether the device is registered as a medical device, and whether temperature monitoring and a skin-protecting pad are used.
• If during the procedure you feel burning that does not pass after the first few minutes and increases, or a sharp pain, say so immediately.
• Ask for a follow-up examination to be planned in the months after the procedure; paradoxical fat increase can only be noticed at a late stage.
• Remember that cryolipolysis is not a method of losing weight or a treatment for cellulite; if your expectation relates to the appearance of cellulite, see our article “Cellulite”.

When choosing where to have the treatment, our article “A 10-Point Safety Checklist for Choosing a Clinic and Physician for Medical Aesthetics” may be useful to you.

Where is scientific knowledge limited?

Why paradoxical fat increase occurs, in whom it is more likely and how often it really happens are not known for certain. Estimates of frequency range from one in twenty thousand treatments to one in a few hundred people; this difference stems partly from device models and partly from the short follow-up of the studies and from the fact that not all cases are reported. Most studies of side effects were carried out with particular devices, and the results may not apply to every device. Problems such as frostbite, muscle weakness and hernia, meanwhile, are known largely from case reports. For this reason you cannot be given a personal risk rate; this page is for information and does not replace an examination.