Pepper spray contains three core components: an active irritant derived from chili peppers, a liquid carrier that dissolves it, and a pressurized propellant that forces it out of the canister. The irritant is a natural oily resin called oleoresin capsicum, or OC, extracted from dried, ripe chili peppers. Everything else in the canister exists to deliver that resin to a target’s face as efficiently as possible.
The Active Ingredient: Oleoresin Capsicum
Oleoresin capsicum is extracted from peppers in the Capsicum annuum family using a volatile solvent process that pulls the oily resin out of the dried fruit. This resin contains a group of compounds called capsaicinoids, the same chemicals that make hot peppers burn your mouth. The most important of these is capsaicin (technically trans-capsaicin), which is the primary driver of the pain and inflammation pepper spray causes.
OC concentration in commercial pepper sprays ranges from 0.5% to 20% of the total formula. On the Scoville scale, which measures pungency, most self-defense sprays fall between 2 million and 5 million Scoville Heat Units. For context, a habanero pepper tops out around 350,000 SHU. Pepper spray is roughly four to fourteen times hotter than one of the hottest peppers most people have ever tasted.
Carriers and Propellants
OC is an oily resin, so it needs a carrier liquid to dissolve it into a sprayable solution. Common carriers include ethanol, isopropanol (rubbing alcohol), propylene glycol, and occasionally petroleum-based solvents like kerosene. Some formulations use acetone or d-limonene (a citrus-derived solvent). The choice of carrier affects how the spray feels on the skin, how quickly it evaporates, and how well it sticks to a target.
The propellant is the pressurized gas that pushes the liquid out when you press the trigger. Nitrogen and carbon dioxide are the most common choices, though some canisters use propane, butane, or synthetic gases like tetrafluoroethane. The propellant determines the spray pattern (stream, cone, fog, or foam) and how far the spray can reach. It’s also the component most responsible for a canister’s shelf life. Over time, propellant pressure leaks through the valve seal, and once enough pressure is lost, the canister produces weak, sputtering bursts instead of a strong stream. This is why pepper spray canisters have expiration dates, typically two to four years from manufacture. The OC itself stays relatively stable, but the delivery system gradually fails.
How Capsaicin Affects the Body
Capsaicin targets a specific pain receptor called TRPV1, which is found on sensory nerve cells throughout your skin, eyes, nose, mouth, and airways. Under normal conditions, TRPV1 receptors respond to actual heat and physical damage. Capsaicin essentially tricks these receptors into firing as though your tissue is being burned, even though no real thermal injury is occurring.
When capsaicin binds to TRPV1, it opens a channel that floods the nerve cell with calcium ions. This triggers the release of pain-signaling chemicals, particularly substance P and a peptide involved in inflammation. The result is an intense burning sensation, rapid swelling, and a flood of protective responses from your body: your eyes slam shut involuntarily (a reflex called blepharospasm), tears pour out, your nose runs, and your throat and airways constrict and produce mucus. Sneezing, coughing, and retching are common.
What the Effects Feel Like and How Long They Last
Symptoms hit fast. Within about 20 seconds of exposure, you experience eye pain, an inability to open your eyes, a sharp burning sensation in the nose and throat, heavy tearing, and difficulty breathing comfortably. Most people are effectively incapacitated for several minutes, which is the entire point of the product as a self-defense tool.
If you move away from the source and get fresh air, the worst symptoms begin fading within about 15 minutes. But “fading” doesn’t mean gone. Research tracking people exposed to defensive spray found that at the one-hour mark, nearly everyone still had lingering symptoms, particularly in the eyes, throat, and respiratory system. Eye irritation and a raw feeling in the throat were the most persistent complaints.
Even at one month after a single direct exposure, some individuals still reported symptoms, especially in the mouth and throat. Long-term follow-ups at eight to ten months found occasional complaints like worsened asthma, reduced exercise tolerance, or lingering coughing fits after physical activity. However, clinical exams and lung function tests at that point showed no measurable abnormalities, suggesting these late symptoms resolve without permanent damage in most cases.
Why Formulations Vary
Not all pepper sprays are identical. Law enforcement sprays, civilian self-defense products, and bear sprays use different OC concentrations, carrier solvents, and propellant pressures depending on their intended use. A bear spray, for instance, needs to project a wide fog pattern over a longer distance (typically 15 to 30 feet), so it uses higher propellant pressure and a broader nozzle. A compact keychain canister prioritizes portability and uses a tighter stream with less propellant.
Some products also blend OC with synthetic irritants like CS (the compound in traditional tear gas) or CN (an older tear gas agent) to create a combined effect. These additions change the symptom profile slightly but don’t alter the core formula: an inflammatory compound dissolved in a carrier, pushed out by compressed gas. The OC resin from chili peppers remains the primary ingredient in virtually all products marketed as pepper spray.