What is the best way to whiten discolored teeth from purging?

Ortho phosphoric aci: Superphosphozyme by biotics will whiten teeth. Use a qtip with few drops use on teeth and rinse off using water with little baking soda to remove any acid (or just rinse thoroughly).

May need restoration: Purging can damage tooth enamel. Vomitus is acidic, and can decalcify tooth enamel, making it more susceptible to staining. First must control purging usually associated with eating disorders. Seek therapy to control disorder. Then dentist can bleach away surface stains, or restore damaged teeth. There are lots of support venues to help control cause of the discoloration, the purging.