Lip piercings usually take 6-8 weeks to heal completely, and it is rare to develop an infection from one, because the mouth contains an enzyme that inhibits bacteria. Usually swelling will occur 2-3 days after the piercing, which could last 7-10 days. Lip piercings have a tendency to move position on the inside of the lip, which is a process called "nesting-. .
You must rinse your mouth with a mouthwash (like Listerine or cepacol) after meals or eating. For the first few weeks you should suck on antibacterial throat lozenges. Doing this can reduce the chance of infection, and also reduce swelling.
You also have to clean the front of the piercing by soaking a cotton wool ball in salt water or saline and leaving it on the piercing for 2-3 minuets to dissolve the crusting in the morning. If you touch it with your bare hands, you are getting bacteria in the piercing, which is bad, and can cause an infection. You can make salt water by dissolving ½ teaspoon of Sea Salt or table salt in a ¼ glass of warm water.
You can also use lavender oil on your piercing. It helps healing, and reduces the tenderness of the wound. You should apply a small amount with a cotton ball after cleaning, then move the jewelry, so that the oil gets into the wound. If you do use the oil, use a tissue to remove any extra, because if you leave it on, it can irritate the skin. Lavender oil can be purchased at supermarket.
When you get a lip piercing, you should also eat a lot of cold things. Such as frozen yogurt, ice cream, or suck on ice cubes. The cold things help the healing, and reduce swelling and pain. Be very careful when you're chewing so that you don't bite the ring or stud, because you could possible shatter a tooth. .
You also have to check that the jewelry is screwed on tight. The ball should be turned clockwise to tighten it (on a stud piercing). Make sure you clean your hands before ever touching the piecing.