How Long Does Neck Lift Swelling Last?

Swelling following neck lift
surgery varies from patient to patient and depends on the surgical technique
and wound healing characteristics of the patient.  The majority of swelling usually resolves in about two weeks
following neck lift surgery.  At
this point, most patients can return to work and resume normal activities.  In most cases, total resolution takes
about three months.  In rare cases,
swelling may persist for up to six months following surgery.

It’s important to realize that more
aggressive neck lift procedures cause more swelling, which can last for longer
periods of time.  Elevation of the
head and decreased salt intake may help decrease swelling
after surgery.  Swelling is normal
following surgery, but persistent or extreme swelling should be evaluated by
your surgeon, especially if it’s accompanied by bruising. 

Hard to say without photos or exam.  Your descriptions of "watermelon" size swelling are a unusual.  While you are still early in your post operative course, I would suggest contacting your surgeon and letting him/her know what is going on.