Zeltiq is one of the safest procedures available, especially among fat reduction procedures. It was FDA-approved for fat reduction in September of 2010 and has been safely used in Europe for approximately 5 years. The reason why it is so safe is that the cold exposure is not to such an extreme that it immediately kills fat cells; rather, the cold exposure initiates natural programmed fat cell destruction, which is why it takes 2 months to see the results. The exposed fat cells naturally degrade and the byproducts excreted by your body. The only contraindications to undergoing Zeltiq is if you have rare conditions of cold-intolerance.
The procedure may be slightly uncomfortable during the first few minutes of treatment, but it is more of an odd pulling and cold discomfort than pain and gradually turns into a barely noticeable numbness. This odd feeling is greatest with the largest treatment head/applicator, and less with the small and medium applicators. Immediately after the procedure, the treated area may have mild to moderate tingling, numbness, and soreness. Mild bruising is sometimes seen, but is uncommon. The soreness may last for 2-3 days and feels like the muscle soreness you get after a round of intense exercise. The tingling and numbness feels just like the sensation your skin has after intense cold exposure. It lessens over time and is usually limited to 2-3 weeks. Zeltiq does not cause long-term nerve damage.
With standard settings, there should be little if any bruising or pain. Sometimes the vacuum settings are increased in thinner individuals to get proper exposure of the treatment area to the cold applicator. The higher suction could increase the chance of bruising, though it is still usually minimal and limited. The temperature is currently not altered in the current model of the Zeltiq device.
When a device like this comes along that claims to be so effective with so few risks, it is usually too good to be true, but with the Zeltiq device, it is both good and true.