Kapha-type allergies occur when excess kapha collects in the stomach and lungs. One way to relieve this congestion is purgation therapy (virechana). Use flaxseed oil (available in most natural food stores), and take 1 teaspoon 2 or 3 times a day for 2 or 3 days. This will be quite effective. Or you can use triphala (see below).
