Can ivc filter cause your legs to swell?

Possibly: Ivc filters do not themselves cause swelling of the legs, but clot can build up below the filter and of sever enough, can block drainage of blood from the legs back to the heart - this results in both legs swelling, sometimes quite large. In addition, leg swelling can be caused from a clot in the leg or blockage of lymphatic drainage channels.

Not the filter: Before one gets a filter, there was already a clot. That means the vein involved will never be normal and even without filter can cause swelling usually after some time upright. The filter unless along with blood thinner actually can cause propagation of clot and more swelling of the legs..