Oleoresin capsicum (OC) is a thick, reddish-brown oily liquid extracted from dried, ripe chili peppers. It contains over 100 chemical compounds, with capsaicin as its primary active ingredient. You’ve almost certainly encountered it in some form: it’s the active substance in pepper spray, the basis for topical pain-relief creams, and a flavoring and coloring agent in the food industry.
What’s Actually in It
OC is produced by soaking dried chili peppers (usually varieties of Capsicum annuum) in a volatile solvent, which pulls out a concentrated mixture of oils, pigments, and the compounds responsible for heat. The result is a complex blend of more than 100 chemicals, including alcohols, esters, terpenes, and the group that matters most: capsaicinoids.
Capsaicinoids are the molecules that produce the burning sensation. Depending on the pepper variety, OC contains between 0.01% and 1% capsaicinoids by dry weight. Within that fraction, the breakdown looks like this:
- Capsaicin: ~70% of total capsaicinoids
- Dihydrocapsaicin: ~20%
- Nordihydrocapsaicin: ~7%
- Homocapsaicin and homodihydrocapsaicin: ~1% each
Together, capsaicin and dihydrocapsaicin account for 80 to 90% of the heat-producing power in any given batch. The remaining compounds contribute color, aroma, and flavor but relatively little pungency.
Why It Burns: The Biology
Capsaicin triggers a specific pain and heat receptor found on sensory nerve fibers throughout your skin, mouth, eyes, and airways. This receptor, called TRPV1, normally activates in response to actual heat (temperatures above about 109°F) and acidic conditions. Capsaicin bypasses both of those triggers. It binds directly to the receptor’s interior, forcing it open and flooding the nerve cell with calcium and sodium ions. Your nervous system interprets this the same way it would interpret a real burn.
What makes this especially effective is that capsaicin also lowers the temperature threshold at which TRPV1 fires. So after exposure, even normal body heat can feel painful. In inflamed tissue, this effect is amplified further, because inflammation keeps the receptor in a sensitized state. That’s why a second application of OC to already-irritated skin feels dramatically worse than the first.
Use in Pepper Spray
OC’s ability to cause immediate, intense pain across multiple body systems made it the standard active ingredient in defensive sprays and riot-control agents. Exposure typically produces effects within seconds: involuntary eye closure, tearing, coughing, difficulty breathing, and a burning sensation on exposed skin. The most significant responses occur in the lungs and airways, which can spasm and make breathing feel restricted.
Every U.S. state allows civilians to purchase and carry pepper spray without a permit, though many states impose restrictions on canister size, OC concentration, or buyer age. California limits canisters to 2.5 ounces. New Jersey caps them at three-quarters of an ounce and requires buyers to be 18 or older with no felony record. Michigan and Wisconsin set a maximum OC concentration of 10%. Hawaii requires a license and limits canisters to half an ounce. Massachusetts and New York require in-state purchase from a licensed dealer, with no online sales allowed.
How to Decontaminate After Exposure
If you or someone near you is exposed to OC spray, the priority is moving away from the source and getting into fresh air. Remove any contaminated clothing, since the oily residue will keep irritating whatever it touches. Then flush affected skin and eyes with large amounts of water. Avoid rubbing your eyes or face, which just spreads the oil further.
A randomized controlled trial on volunteers exposed to OC spray found that washing with baby shampoo provided faster relief from acute symptoms compared to water alone. The mild surfactants in baby shampoo help break up the oily residue that plain water can struggle to dissolve. Most symptoms resolve on their own within 30 to 60 minutes once the OC is removed, though skin redness and sensitivity can linger longer.
Medical Uses for Pain Relief
Capsaicin derived from OC has a well-established role in pain management. When applied to the skin repeatedly, it depletes the nerve endings of a chemical messenger involved in transmitting pain signals. The initial applications burn, but over days of consistent use, the treated area becomes less sensitive to pain.
Topical capsaicin is available as creams, lotions, gels, and prescription-strength patches. Common uses include postherpetic neuralgia (the lingering nerve pain that follows shingles), rheumatoid arthritis pain, muscle strains, and diabetic nerve pain in the feet. Over-the-counter creams are typically applied three to four times a day. Prescription patches deliver a higher concentration and are left on for 30 to 60 minutes in a clinical setting, depending on the condition being treated.
Capsaicin does not cure the underlying condition. It reduces the pain signal itself, which for chronic nerve pain can be the difference between manageable days and miserable ones.
Role in the Food Industry
Beyond self-defense and medicine, OC and its close relative paprika oleoresin are widely used in food production. Paprika oleoresin, extracted from milder pepper varieties, is approved by the FDA as a color additive for foods. It gives products a natural red-orange hue without synthetic dyes and is exempt from the batch certification process required for artificial colorants.
Hotter versions of capsicum oleoresin are used to standardize the heat level in sauces, snack seasonings, and processed meats. Because the capsaicinoid concentration in raw peppers varies from harvest to harvest, manufacturers use oleoresin to deliver a consistent, measurable level of pungency. The extract can be precisely diluted to hit a target Scoville rating, something that’s difficult to achieve with whole peppers alone.