Large, hard and painful lump after Cool Sculpting. What is causing this?

CoolSculpting is a wonderful treatment, but patients need to be reminded that it is a "procedure". Meaning there is some recovery time involved. Rarely is there "down time" but after a CS treatment for up to 4 weeks patients can experience lumps, knots, bruising, soreness, swelling, cramping, numbness, itching, and other possible side effects. None of the above should be debilitating but it is important to understand that the procedure can sometimes cause temporary side effects. I would not worry just yet regarding the lump. It is most likely a bruise or a hematoma with some swelling and will resolve with time. Of course, it is difficult to say without seeing you in person. If you have a concern, always contact your primary provider so that he or she may see you and treat you appropriately. 

It is possible a hematoma or collection of blood developed in that area. Taking an NSAID and using a heating pad may help relieve the symptoms you are experiencing. 

Firm areas should be from a combination of swelling and or bruising.  An in person exam is best to evaluate the area.

A very tiny percentage of patients treated with CoolSculpting (of more than half a million treatments, it has been reported in just a handful of patients) develop small firm areas in the treated zone.  These usually resolve within 2 to 4 weeks and do not cause any harm.It is also conceivable that you have a hematoma, which shoukd resolve as well.Your treating dermatologist should be able to tell you which condition is present.

Coolsculpting induces a process by which a percentage of fat cells are killed (this was actually developed by two Harvard Dermatologists) and the body clears then over weeks. You might be having this lump as part of the healing and clearing process so don't get too worried. It would be best if you saw your treating physician to evaluate you as often its easier to evaluate in person. They can give you guidance on how to handle the discomfort.