Cooking up delicious spicy food can come at a price… a price many of us have paid! If you’ve ever cut up some jalapeños and scraped out the seeds with your bare hands, you know the symptoms: excruciating pain. This pain is caused by an oil-soluble substance called capsaicin (pronounced cap-say-sin). Capsaicin is the active component found in all hot peppers. It’s what makes them so delicious to eat (provided you can take the heat) and causes the burning pain on your skin. The good news is that capsaicin doesn’t actually cause any tissue damage. This may be of little comfort to you if your hands feel burnt and the only way to sleep is by clutching an ice pack. But if we dig a little deeper, we’ll discover a fascinating world involving neurotransmitters, pain signals, and a brain tricked into thinking your skin is engulfed in flames.
When you eat or touch hot chilis, capsaicin particles penetrate your skin, move through the tissue, and trigger deeper nerves. Here’s where it gets a bit technical. Capsaicin acts like a neurotransmitter and binds to a receptor called VR1 (vanilloid receptor one), forcing it to deform. Usually, the VR1 only changes shape at temperatures at or above 42ºC (108ºF). When it deforms, it releases charged particles called ions into the nerve cell, transmitting a signal through the nerves to the brain. The signal itself is the same as what VR1 would send if it were sensing heat. The brain doesn’t know the difference, so you experience the same pain from chili peppers as you would from a burn. Learn more here.