A chemical signal, not a hotter meal
Capsaicin activates TRPV1 receptors, nerve sensors that normally respond to potentially damaging heat. They send a heat-like signal to the nervous system even when the food itself is not hot. The brain and body react to that signal much as they might to warmth: sweat glands become active, and blood vessels near the skin can widen, making the face feel flushed.
Why sweat can help
Sweat cools only when it evaporates. To change from liquid into vapor, water draws heat from the skin; moving air helps carry the vapor away. That can make the skin feel cooler after the initial burn, especially in dry conditions. In humid air, sweat evaporates more slowly, so the cooling effect is weaker and sweat may simply bead on the skin.
The response is a local cooling aid, not a dependable way to lower the body’s internal temperature. And because the heat signal is sensory, spicy food can feel intensely hot without raising the food’s temperature—or necessarily making the body warmer overall.
