My nipple piercing is infected i've had it for 8 months how. how do i treat it? just clean it with salt water?

Negative: If you think it's infected, an antibiotic is indicated. Better get that looked at. It could be staph or, worse yet, mrsa.

Infected piercing: Check for signs of infection: ^'ed redness, warmth, swelling. ^'ed tenderness, pus, red streaking, swollen lymph nodes or fever. Recommend keeping piercing in place unless directed by Dr (if removed – drainage tract will close up w ^'ed risk of abscess formation). Call Dr for medical evaluation. Your Dr may prescribe oral antibiotics or antibiotic ointments to apply to piercing site.