Capsaicin may be familiar to many as the active ingredient in some pain relief products. Traditionally it is known as the “heat” in chili peppers and is used in pepper sprays to repel or subdue unruly or dangerous animals or humans.  How it works and its unusual chemical “relatives” are discussed below.

How Does Capsaicin Work?

Capsaicin acts on pain and heat receptors (nerve endings) found in mucus membranes, the outermost layers of your tongue, nose, eyes and intestinal tract.  Mucus dissolves the chemicals so we can taste and smell them.

Capsaicin is chemically related to Vanillin, the active ingredient of vanilla. They share the same ring structure you see in the image below, top right corner. Where they differ is the longer chain to the lower left.

This longer chain of atoms makes capsaicin behave like oil or fat. What this means is that if you get more chili pepper in your food than you can tolerate, you can’t chase it away with water or beer. The best at hand remedy is usually milk which contains casein, a protein that is lipophilic (fat loving) and aids in capsaicin removal.


Capsaicin is a chemical responsible for the “heat” in chili peppers. It is related to and shares some chemical properties with vanilla.


Why Use Capsaicin in Repellent Sprays?

The simple reason that capsaicin is used in repellent sprays is the pain it causes when it gets into ones eyes, or a bear’s. The pain is intense enough to cause the eyes to clamp shut tightly to the point of incapacitation.  The other reason is that this is reversible and does no permanent damage.

How Does Capsaicin Affect Pain Relief?

Strangely enough, the reason capsaicin is used in pain medication is essentially the same reason people eat it. It apparently triggers the production of endorphins, the naturally occurring pain relief chemicals your body releases in response to pain.

This production of endorphins may in fact be what makes capsaicin work on some types of joint pain.  The friction of bone against bone in knees, hips and elbows is reduced by synovial fluid which acts as a lubricant. The tissues in these joints also have receptors that respond to the chemical heat effects of capsaicin.

Medications that relieve pain using capsaicin also contain compounds that allow it to first be aborbed by the skin and then penetrate to the joints underneath.

Capsaicin The Molecular Model

As with most of the chemical compounds we feature, you can build one for yourself using our 3D Molecular Model Builder.


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