This is probably one of those things that you dread the most...other than your parents finding out you just pierced yourself...and something a lot of people aren't so sure how to recognize or especially, how to treat.
Infections are usually characterized with puffiness, redness, puss (that doesn't look like crusties), very sore, swolen, just looks "bad". Now don't get this confused with the first weeks of a new piercing. Infections can be caused by not cleaing your piercing properally or enough, having really shitty jewelry in the hole, maybe even your body's reaction to this sudden wound (which is what a piercing is, a wound).
If it looks like something you can get under control and you haven't allowed it to progress too far, I recommend extra TLC (tender, love, and care). Use anti-bacterial soap (if it's an outside piericing, as in not oral) with water to dilute it, I like using a Q-tip to clean piercings...it's much easier this way and cleaner since you can just throw the q-tip away when you're done. Anyway, dampen one end (make sure your hands are clean by the way), and gently rub some soap on that end and then gently work it around the piercing. However remove crusties, if there are any, before you do that by soaking them in water, a good way to do this is to take a shower that gets it off easily and painlessly (as far as I know at least). This is a time when you CAN use hydrogen peroxide, but ONLY if you have an infection.
If it's an oral piercing, you can actually dilute some hydrogen peroxide and use it as a mouth wash, however don't sallow it by any means, and follow the directions on the bottle. It should tell you have to dilute it so you can use it as a mouth rinse.
If it continues to stay infected after at least a week of extra TLC go to a doctor or trusted piercing studio for their opinion, DO NOT REMOVE THE JEWELRY! If you remove it and allow it to heal before clearing up the infection, it'll simply heal OVER the infection, trapping it under the scab, which can cause some more serious problems. DO NOT allow a infection to go untreated, take care of yourself, especially your piercings!!
