Hot and spicy, cayenne pepper adds zest to flavourful dishes around the world and health to those brave enough to risk its fiery heat. The hotness produced by cayenne is caused by its high concentration of a substance called capsaicin. Capsaicin has been widely studied for its pain-reducing effects, its cardiovascular benefits, and its ability to help prevent ulcers. Capsaicin also effectively opens and drains congested nasal passages.