I was just reading about this but I can't remember where. Let me sleep on it and maybe it will turn up. :)
Mostly it's a Pitta disorder, which means you run too hot overall and have too much bile in the liver. Lecithin, carrot juice, carrot cleansing salad (see Cleansing Salad post in FAQ), cold showers, staying out of hot sun, help a lot. stick to a mostly vegetarian diet with EVCoconut oil. Avoid black pepper and other hot, spicy foods for the most part.