What do I do if my baby bites while nursing?

Stop the session. It is most effective to immediately stop the feeding session. Do not purposefully yell or scream as this will just scare baby. After a few minutes start nursing again. Babies often bite when they are bored, full or teething. Watch your baby carefully during nursing and if they stop actively sucking take them off the breast. If your baby is teething allow them to chew on washcloths.
Remove from breast. Baby learns that if she bites food (the breast) gets taken away. It's stimulus/response training.