Try ice 5 to 10 minutes on, then off for 15 to 20 minutes. You can also get an ice chip and hold it with your tongue to the inside of the lip. Time will take care of the rest of the swelling.
Depending on the type of piercing. If you have oral piercings lip, labret, monroe, madonna, tongue etc. Crushed ice should be used on the site to ease swelling, cold beverages like Slurpies, Freezies...