According to my aftercare guide that I got from the piercer, which was put together by the Association of Professional Piercers (APP) (yes, there is such a thing- make sure your piercer is certified!), the ONLY thing to put on a piercing is saline solution. It's also ok to wash GENTLY in the shower using mild soap. That's it. No antibiotic ointment, no peroxide, no nothing. Salt water is your friend.
The reasoning behind it is akin to what Abigail just said- you want the GOOD bacteria to still be around to help your skin heal AROUND the piercing instead of thinking the piercing is a foregin object that needs to be rejected. Your body is the best healer there is, which is why you keep the area clean and avoid fiddling with the bars/hoops before 6 or 8 weeks (the shortest amount of time recommended before a jewelry change). Also, my piercer said to come back to her for the first jewelry swap, so she could show me the right way to do it and make sure that my nipples are ready for it.
If anyone would like, I can post the entire part of the pamphlet from the piercer's association on nipple piercing aftercare. Or go and check out the APP website:
www.safepiercing.org
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She answers hard acrostics, has a pretty taste for paradox
She quotes in elegiacs all the crimes of Heliogabalus
In conics she can floor peculiarities parabolous
-C'hi