The intense, fiery feeling that spreads across your mouth and throat after consuming spicy food is a common experience, but it is not a thermal burn from actual heat. This powerful sensation is a direct result of a chemical irritant interacting with your nervous system. This reaction is known as chemesthesis, which is the chemical activation of nerve endings that transmit signals of pain, touch, and temperature. The body’s alarm system responds to this chemical compound, tricking the nerves into believing the tissue is physically on fire.
Identifying the Source of the Burn: Capsaicin
The molecule responsible for this culinary heat is capsaicin, found almost exclusively in chili peppers. Capsaicin is a secondary metabolite produced by the plant as a defense mechanism against predators. The highest concentrations of this compound are found in the white pith, or placenta, that holds the seeds inside the chili fruit.
Capsaicin is classified as a non-polar molecule, giving it an oily, hydrophobic nature. This characteristic is crucial because non-polar substances do not dissolve easily in water. When trying to wash the burn away with water, the capsaicin simply spreads around your mouth and throat, often intensifying the discomfort.
How Capsaicin Tricks Your Nerves
The physical burning sensation results from capsaicin binding to a specific sensory receptor found on nerve cells throughout the body, including the mouth and throat. This receptor is known as the Transient Receptor Potential Vanilloid 1, or TRPV1. The TRPV1 receptor’s normal function is to detect actual high temperatures, specifically above 109°F (43°C), physical abrasion, or acidic conditions.
When capsaicin contacts the tissue, it binds directly to the TRPV1 channel, forcing it to open. This action causes a flood of calcium ions into the nerve cell, generating an electrical impulse that mimics the signal produced by genuine heat damage. The brain interprets this signal as a painful burning sensation, even if the food is cold.
As the spicy food travels down, it continues to activate these receptors in the throat and esophagus, causing persistent irritation. This chemical assault triggers a protective inflammatory response from the body. The local tissue reaction can involve swelling and increased mucus production, which contributes to the feeling of a sore or irritated throat. The body perceives capsaicin as a foreign threat, initiating processes like sweating and a runny nose to expel the irritant.
Soothing the Irritation: Immediate Relief
Since capsaicin is an oily compound, the most effective remedies either dissolve the molecule or block its interaction with the TRPV1 receptor. Whole milk and other dairy products work well because they contain casein, a lipophilic protein. Casein attracts and surrounds the non-polar capsaicin molecules, effectively washing them away from the nerve receptors.
Cold temperatures offer temporary relief by directly desensitizing the nerve endings, momentarily calming the hyperactive TRPV1 receptors. Consuming sugary foods, such as honey or a sugary drink, can also help by interfering with the chemical binding process on the receptors.
Acidic liquids, such as citrus or tomato juice, may provide a slight neutralizing effect on the capsaicin molecule itself. The goal of immediate relief is to physically remove the capsaicin from the tissue or temporarily soothe the irritated nerves until the compound passes through the digestive system.