Are you alergic to black pepper or chili pepper? They come from completely different plants.
Can you handle hot salsa or hot sauce like tobasco? If so, I *think* you can get away with putting a drop or two of tobasco in your lemonade. (I'm not an expert, this is just day 2 of my fast)
The cayenne is there to help provide some trace minerals and help you sweat out the toxins.