The nipple is fleshy enough to be pierced securely behind plenty of skin to prevent rejection. That doesn’t mean a nipple piercing can‘t reject jewelry, though, especially if it’s not done properly in the first place. If the jewelry gauge is too thin or the piercing isn’t deep enough, you run the risk of rejection.
Consequently, what happens if your piercing is too small?
If you still have the feeling that the post or earring of your piercing is too small and feels too tight to the point of being in pain an probably noticing redness, swelling and lymph or even puss, you should consult a professional to have it taken out and replaced with a proper length post or ring.