Swelling actually isn't that uncommon. This is an allergic reaction. I do have to mention that I'm not a doctor and if you find this condition something of concern, please be sure to discuss with your doctor. With that said - you might try ibuprofen to help with the itching and swelling. Here's a bit of a reference: Poison Ivy. It is a PDF document. I've read a few mentions about using an anti-inflamatory like ibuprofen. When in doubt though be sure to consult your doctor.