If you were asked to list the most common uses of chili pepper, you would naturally think of it in terms of spicing up food. However, very few people would think of using it as the main ingredient in a pain relief cream. I know this may sound counter intuitive but chili peppers have traditionally been used as a topical painkiller, usually made by crushing the peppers and mixing them with a neutral base cream to make a home made pain relief cream or applying the mashed up peppers directly to the skin.
A modern version of this is the capsaicin pain relief cream available in tubes or jars or as the active ingredient in heating pads for sale at most drugstores. Among the conditions it is used for are back pain, bursitis, fibromyalgia, joint pain, muscle pain, nerve pain, osteoarthritis, pain due to diabetes, neuropathy, phantom pain after amputation, post-herpetic neuralgia, post-surgical neuropathic pain, and rheumatoid arthritis. It can also relieve itching (pruritis).
But what is it about capsaicin that makes it so effective in relieving pain? The answer lies in its distinctive mouth-burning, eye-watering, and sweat-breaking spiciness. Capsaicin or 8-methyl N-vanillyl 6nonamide is one of the six capsaicinoid compounds in chili peppers. It works by activating the chemical terminals of sensory neurons called transient receptor potential cation channel subfamily V member 1 (TRPV1), which increases membrane permeability to elements like calcium and sodium.
This triggers the release of substance P, which is primarily responsible for the sensations of pain we experience inside our mouths when eating a habanero chili pepper. When these chemical terminals are flooded with capsaicin, they open and allow the latter to enter specific pain fibers, letting extra calcium inside the cells until the nerves become overloaded and shut down. When these cells shut down, it temporarily numbs the feeling in that specific area where it was applied.
The brain responds to the burning sensation by releasing endorphins, the body's natural painkiller. Endorphins are a class of neurotransmitters produced by the body to respond to any kind of pain, and bonds to some of the same receptors in the brain as the opioid morphine. The term itself is a blend of two words coined by American scientists Rabi Simantov and Solomon H. Snyder, “endogenous” and “morphine" and literally means "morphine produced naturally in the body.” Endorphins are also known to cause a sense of well-being, and is the attributed cause of a phenomenon called “runner's high.”
This is largely because its release is triggered by exercise, which puts a great deal of wear and tear on the body and causing muscle pain. The muscle pain in turn becomes the signal for the body to release endorphins. Similarly, capsaicin has also been known to trigger the release of endorphins.