How to treat a swollen ear piercing?

Depends: Was it a recent piercing? It's natural to have some swelling after an injury. A cold compress on the area may help. If the area is red, painful, and/or you have any discharge from the area it may possibly be infected. In that case you need to see your doctor.

Infected??: Check for signs of infection: ^'ed redness, warmth, swelling. ^'ed tenderness, pus, red streaking, swollen lymph nodes or fever. Recommend keeping piercing in place unless directed by Dr (if removed – drainage tract will close up w ^'ed risk of abscess formation). Call Dr for medical evaluation. Your Dr may prescribe oral antibiotics or antibiotic ointments to apply to piercing site.

You get it: Medically evaluated before possible infection progresses.