Question of the Day: Why are bell peppers spicy to me?
Quick Answer: There are only two plausible reasons that a bell pepper would be spicy to someone. It has cross-pollinated with hot peppers and is therefore no longer truly a bell pepper, or the person has a food allergy to bell peppers.
Bell peppers are not capable of producing capsaicin which is the chemical that gives chilies their heat. That is why they have a heat index of zero.
On rare occasions, though, bell peppers have been known to crossbreed with other types of peppers. The resulting hybrid could have the appearance of bell pepper but a spicy flavor.
Bell peppers contain a wide array of chemical compounds that could, in theory, cause an allergic reaction. If you consistently experience burning when eating bell peppers, it would be advisable to consult a physician.