What causes reddness in the bottom of the feet?

Could be normal: The only thing in your body that is red is the red blood cell so if a body area turns red it means increased blood flow. The soles of the feet normally have high blood flow and are red compared to the top of the feet. If the redness is associated with itching and rough skin it may be a contact allergy. If the redness is associated with burning it may be neuropathy. Either way see your md.