What make atomic fireball candy hot?

Atomic Fireball candy gets its heat from the chemical compound capsaicin. Capsaicin is a naturally occurring compound found in chili peppers and is responsible for the spicy or "hot" taste sensation. When capsaicin comes into contact with the taste buds on the tongue, it binds to receptors that send a signal to the brain indicating a burning or stinging sensation. In Atomic Fireball candy, capsaicin is used in a concentrated form to create an intensely spicy and hot flavor experience.