The paradoxical side effect of CoolSculpting: Melt away the pounds or freeze them in place?

By Alpana Mohta, MD, DNB, FEADV, FIADVL, IFAAD | Fact-checked by Barbara Bekiesz
Published July 18, 2023

Key Takeaways

  • CoolSculpting is a popular non-invasive procedure that freezes fat cells using cryolipolysis. However, it carries the risk of a rare complication called paradoxical adipose hypertrophy (PAH), which can lead to disfigurement.

  • The reported incidence rates of PAH range vary widely—from 0.033% to 1%.

  • If your patients are interested in cryolipolysis, counsel them about risk factors for PAH, which include multiple cryolipolysis sessions, treatment on the abdomen, and being male.

With 41.9% of US adults classified as obese,[] it’s no wonder the market for weight loss solutions is hotter than ever. CoolSculpting, a seemingly too-good-to-be-true procedure that claims to freeze away fat, is celebrated for its quick recovery time and resulting weight loss—without requiring any changes to an individual’s diet or exercise routine. 

This non-invasive procedure has generated more than $2 billion in revenue, according to a 2023 article in the New York Times.[] While popularity is only increasing, it’s important to remember that CoolSculpting is not without its risks. The Times article noted an uptick in adverse events, calling into question the safety of this cosmetic procedure.

Cryolipolysis kills fat cells using freezing temperatures

CoolSculpting is based on cryolipolysis, the brainchild of Harvard University researchers who were investigating how frostbite affects fat cells. Unlike skin, fat has a higher freezing point.[]

With cryolipolysis, controlled cooling temperatures are applied to freeze the fat in the subcutis. This freezing process induces adipocyte apoptosis and triggers cold panniculitis while ensuring the surrounding skin and tissues are preserved. Over time, the treated fat cells break down and are eliminated by the immune system, reducing localized fat deposits in the targeted area.[]

CoolSculpting is manufactured by Allergan Aesthetics, a division of AbbVie, a major pharmaceutical company. The technique is approved by the FDA to target stubborn fat under the chin, jawline, back, abdomen, upper arms, thighs, chest, and flanks. On average, CoolSculpting reduces fat in targeted areas by 10% to 25%. Usually, patients require two visits under supervision. The duration of each session ranges from 35 to 75 minutes.

The risk of paradoxical adipose hypertrophy

With the wide usage of cryolipolysis, there have been reports of a rare complication called paradoxical adipose hypertrophy (PAH).

This complication typically occurs 2 to 6 months after the procedure and results in fatty tissue growth.

PAH is no ordinary issue. Instead, it's a nightmare unfolding in your patient’s body. The fat that should have vanished as if by magic does the opposite—it hardens and grows, and can even form into the shape of the CoolSculpting device applicator. Patients may experience a thickening of the treated area, with the formation of painless swollen masses. 

Supermodel Linda Evangelista publicly shared her experience with PAH following CoolSculpting, sharing her dissatisfaction in an Instagram post. She revealed that the treatment increased her fatty cells and left her permanently disfigured, despite undergoing two corrective surgeries.

What the research says

Naturally, complications can be associated with any medical procedure, including CoolSculpting, but the frequency of these side effects is cause for concern.

While Allergan says the risk of PAH is only 0.033%, the reports in the medical literature suggest the risk is much higher.

Consider the following:

  • In 2014, an article in the Journal of the American Medical Association reported that PAH occurred in approximately 1 out of 20,000 treatments. However, subsequent studies contradicted this low incidence rate.[] 

  • A 2016 letter to the editor of a medical journal and a 2017 study suggested a significantly higher rate of around 1 in every 100 treatments, as noted by the Times.

  • Another investigation, conducted in 2018, evaluated 398 patients over 3 years and also reported an incidence rate of 1%.[]

  • A 2021 study published in the Aesthetic Surgery Journal, co-authored by a research collaborator for Allergan, revealed a notably lower incidence rate. In this study, out of 8,658 CoolSculpting cycles performed on 2,114 patients, the PAH incidence rate ranged between 0.05–0.39%.[]

  • In 2023, a letter published in the Aesthetic Surgery Journal revealed that the risk of PAH following cryolipolysis was 1%.[]

Despite these varying reports, since 2017, Allergan Aesthetics has remained confident in estimating a PAH occurrence of 1 in every 3,000 treatments, according to the Times article. This discrepancy in reported numbers raises concerns regarding the accuracy of the prevalence rate.

According to Aesthetic Surgery Journal authors, the following factors may elevate the risk of PAH in a patient:

  • Prior CoolSculpting procedures

  • Cryolipolysis for the abdomen

  • Utilization of a larger handpiece during treatment

  • Genetic predisposition

  • Being male, with a threefold higher likelihood of developing PAH than females 

Does PAH require medical treatment?

PAH, although not inherently harmful, does not resolve spontaneously. Without intervention, patients may have to wait 6 to 9 months for the affected area's fat to soften before considering liposuction as a corrective measure. 

While reported incidence rates of PAH vary, the author of the 2023 Aesthetic Surgery Journal letter recommends monitoring patients for at least 1 year after cryolipolysis to detect any complications. 

What this means for you

CoolSculpting provides a non-invasive fat reduction option. Be aware of the rare risk of PAH, which can lead to dissatisfaction and disfigurement. Early detection is crucial for prompt diagnosis and proper management. Encourage patients to explore alternative methods like exercise and a healthy diet to achieve optimal weight and overall well-being.

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