Paradoxical Adipose Hyperplasia (PAH) After CoolSculpting: What Is the Risk?

Medically Reviewed By Catherine Hannan, M.D.
Was this helpful?

Paradoxical adipose hyperplasia (PAH) is a rare complication of CoolSculpting, which is a cosmetic procedure to remove subcutaneous fat. The overall rate of PAH is very low, but the incidence may be higher than the numbers reported by the manufacturers of CoolSculpting equipment. CoolSculpting, or cryolipolysis, is a noninvasive treatment that uses controlled, localized cooling to reduce fat just under the skin. During the procedure, a practitioner will place a fold of body fat between two cooling plates. This destroys fat cells by freezing them. The body then clears away the dead cells.

PAH is a rare complication of cryolipolysis, resulting in symptoms such as a firm, painless mass in the treated area. The word “paradoxical” in the name refers to the fact that fat in the treated area appears to have grown larger rather than been reduced.

PAH symptoms can occur about 3–9 months after CoolSculpting. Researchers are still unsure about exactly why PAH develops.

This article looks at the rate of PAH as a complication of CoolSculpting. It also discusses symptoms of PAH and some common risk factors.

How common is paradoxical adipose hyperplasia after CoolSculpting?

Young woman in t-shirt and jeans looking at herself in a full length mirror
Yadira G. Morel/Getty Images

The incidence of PAH varies depending on the source of the statistic.

Researchers in a 2020 analysis cite data from the manufacturers of the CoolSculpting device. Those data say that the rate of PAH is 1 in every 4,000 treatment cycles, or 0.025%.

However, the same researchers found rates up to 15 times higher in their own observations of more than 8,500 people. Other studies have found rates ranging from 1% to as high as 2%.

What are the risk factors for paradoxical adipose hyperplasia?

Through their study of PAH rates, researchers have identified certain risk factors for developing PAH after CoolSculpting, including:

  • being assigned male at birth
  • Hispanic ethnicity
  • having larger pieces of adipose tissue (fat)
  • having the procedure done in the abdominal region
  • a history of CoolSculpting

One case of twin brothers who each developed PAH separately after receiving CoolSculpting at different practices has researchers speculating on whether or not genetics may also be a factor.

What are the symptoms of paradoxical adipose hyperplasia?

The main symptom of PAH is a large, painless, firm, partially mobile mass that develops in the treatment area where the applicators of the CoolSculpting machine were applied to the body.

Some other symptoms that may occur with PAH include:

  • skin discoloration or redness
  • a constricted band at the waistline
  • irregular contouring across the abdomen
  • swelling in the treatment area
Example of paradoxical adipose hyperplasia in woman who received CoolSculpting treatment
A complication of CoolSculpting is PAH, or paradoxical adipose hyperplasia. This occurs when the treated area becomes hardened and enlarged, the opposite of the intended effect. Credit: Misbah Khan, 2018

How do doctors diagnose paradoxical adipose hyperplasia?

Doctors diagnose PAH by performing a physical exam and visualizing and palpating a firm mass at the site of the treatment.

The doctor may also ask you questions such as:

  • Is the mass painful?
  • When did you first notice the mass?
  • How long ago did you receive CoolSculpting treatment?
  • Do you have a history of receiving CoolSculpting?
  • Do you have any other symptoms?

If your doctor diagnoses PAH, they can discuss potential treatment options to reduce your symptoms and help you manage the condition.

What are the treatments for paradoxical adipose hyperplasia?

Treatment for PAH aims to reduce the appearance of the firm, solid masses that can develop. Treatment options can include:

  • laser-assisted liposuction, which can help remove the excess tissue
  • abdominoplasty, or a “tummy tuck,” which is a procedure that cuts out excess skin or fat and sometimes tightens the abdominal muscles in order to create a slimmer and flatter abdomen
  • radiofrequency skin tightening, which uses heat generated by radiofrequency energy to trigger collagen production and cell regeneration in the skin

Research into the effectiveness of PAH treatments is limited. Also, each of these procedures comes with its own level of risk.

Talk with your cosmetic or plastic surgeon about your treatment options — and potential risk factors — to determine the PAH treatment course that is right for you.


PAH is a rare complication that can occur in the months after receiving CoolSculpting, which is a noninvasive fat removal procedure.

The incidence rate of PAH after CoolSculpting varies. The manufacturer of the CoolSculpting device reports a rate of 0.025%, while researchers have found rates as high as 2%.

Symptoms of PAH include a firm, painless, mobile mass in the treatment area; skin discoloration; and skin contour irregularities across the abdomen.

Talk with your cosmetic surgeon about your risk of PAH before you undergo CoolSculpting. If you do develop this rare complication, your doctor can discuss the available treatment options.

Was this helpful?
Medical Reviewer: Catherine Hannan, M.D.
Last Review Date: 2022 Apr 19
View All Cosmetic Procedures Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.