Cannabis contains more than 500 identified chemical compounds, and that number keeps growing as analytical methods improve. The plant produces over 100 cannabinoids, dozens of terpenes, more than 30 flavonoids, and a range of lesser-known molecules like alkaloids and amides. But the chemicals you’re actually exposed to depend heavily on how cannabis is consumed, since smoking, vaping, and eating it each introduce different substances into your body.
Cannabinoids: The Main Active Chemicals
Cannabinoids are the compounds most people think of when they think of weed. They’re produced in tiny, mushroom-shaped resin glands called trichomes that cover the surface of cannabis flowers. Inside these glands, specialized cells synthesize cannabinoids, terpenes, and flavonoids, then store them in a waxy resin beneath a thin outer membrane. That sticky coating you feel on a cannabis bud is essentially a concentrated chemical factory.
THC and CBD are the two most abundant cannabinoids and the ones with the most research behind them. THC is responsible for the high: it produces euphoria, alters sensory perception, and impairs short-term memory. CBD doesn’t produce intoxication and may actually reduce some of THC’s less pleasant side effects, like anxiety and paranoia.
Beyond those two, the plant produces a long list of minor cannabinoids, each with distinct properties. CBN shows potential as a pain reliever and appetite stimulant. CBG may reduce inflammation and protect nerve cells from damage. THCV appears to regulate blood sugar. CBDV has shown anti-seizure properties in both animal and human studies. THCA and CBDA, the raw acidic forms found in unheated cannabis, have their own anti-inflammatory and anti-nausea effects at doses much lower than their heated counterparts. Most of these minor cannabinoids exist in very small concentrations in any given strain, but they contribute to the overall chemical profile.
Terpenes: What You Smell
Terpenes are aromatic compounds that give cannabis its distinctive smell. They’re not unique to weed. Limonene is the same molecule that makes lemons smell citrusy, and pinene is the compound behind the scent of pine trees. Cannabis just happens to produce an unusually diverse terpene profile.
The major terpenes in cannabis fall into two groups. The smaller monoterpenes include myrcene, limonene, pinene, linalool, terpinolene, and ocimene. The larger sesquiterpenes include caryophyllene, caryophyllene oxide, and farnesene. Myrcene is often the most abundant terpene in cannabis flower and is associated with sedating, body-heavy effects. When myrcene levels exceed about 0.5% of the flower’s weight, it tends to produce a heavier, more relaxing experience. Lower levels are linked to more energizing effects. Caryophyllene is notable because it also interacts with the same receptor system that cannabinoids use, making it a terpene that can directly influence how the plant affects your body.
Flavonoids and Cannflavins
More than 30 flavonoids have been identified in cannabis, including common ones like quercetin, apigenin, and luteolin that also appear in fruits and vegetables. What makes cannabis unique is a small group of flavonoids found nowhere else in nature: the cannflavins. Four have been isolated so far, named cannflavin A, B, C, and isocannflavin B.
Cannflavins exist in trace amounts. Cannflavin A ranges from 0.000013% to 0.019% of the plant’s dry weight, and cannflavin B ranges from about 0.00055% to 0.0064%. Total flavonoid content in the flowers runs between 0.07% and 0.14%, with leaves containing roughly three times more. Despite their low concentrations, cannflavins have drawn interest for their anti-inflammatory properties.
Alkaloids and Other Nitrogen Compounds
Cannabis also produces a lesser-known class of nitrogen-containing chemicals, including alkaloids, simple amines, and amides. Two alkaloids, cannabisativine and anhydrocannabisativine, have so far been found only in cannabis. The plant also contains piperidine, pyridine, and pyrrolidine alkaloids, along with spermidine-type compounds that show neuroprotective properties. Another compound, hordenine (also found in barley), and amides like coumaroyltyramine round out this group. These molecules exist in small quantities and are far less studied than cannabinoids, but they add to the plant’s remarkable chemical complexity.
Chemicals Created by Smoking
The raw cannabis plant is one thing. Setting it on fire is another. Combustion transforms the plant’s chemistry dramatically, generating several thousand additional chemicals that don’t exist in the flower itself. Cannabis smoke contains many of the same toxins found in tobacco smoke, including benzene, formaldehyde, 1,3-butadiene, and benzo[a]pyrene, all recognized carcinogens. It also contains heavy metals like cadmium, lead, mercury, and nickel, plus carbon monoxide.
THC itself becomes a concern during pregnancy, as it may affect behavior, learning ability, and susceptibility to addiction in offspring. The carcinogens in cannabis smoke are a product of burning organic material at high temperatures, not something inherent to the plant. This is why vaporizing at lower temperatures or consuming edibles avoids most combustion byproducts entirely.
Chemicals in Vape Products
Vaping eliminates most combustion toxins but introduces a different set of chemical concerns. Analysis of cannabis vape cartridges in California identified more than 100 terpenes, 19 cannabinoids, and several potentially toxic additives. The most notorious is vitamin E acetate, a synthetic form of vitamin E that looks similar to cannabis oil and was widely used as a cheap thickening agent. Some tested cartridges contained more than 30% vitamin E acetate by volume. This additive was linked to the 2019 outbreak of severe vaping-related lung injuries.
Other additives found in vape cartridges include polyethylene glycols (PEGs), medium-chain triglycerides (MCTs), propylene glycol, and vegetable glycerin. These are used as thinning or cutting agents to make thick cannabis oil easier to vaporize, or simply to stretch the product and reduce costs. All of these additives were detected not just in the liquid but also in the vapor and aerosol that users inhale, though at lower concentrations.
Contaminants From Growing and Processing
Cannabis is a bioaccumulator, meaning it readily absorbs substances from its environment and deposits them in its tissues. This makes it unusually effective at pulling heavy metals like arsenic, cadmium, lead, and mercury from contaminated soil. Phosphate fertilizers rich in cadmium are a common source. In some cases, lead has been deliberately added to illegal cannabis to increase its weight and market value. One case series documented 95 cases of lead poisoning from adulterated cannabis.
Pesticide contamination is widespread even in legal markets. Testing of legalized cannabis products in Washington State found that 84.6% of samples contained significant quantities of pesticides, including insecticides, fungicides, miticides, and herbicides. Some of these were proven carcinogens, endocrine disruptors, or neurological toxins.
Cannabis concentrates like oils and waxes carry an additional risk: residual solvents. Butane, propane, and ethanol are commonly used to strip cannabinoids and terpenes from plant material. If the extraction process doesn’t fully purge these solvents, they remain in the final product. Residual butane and propane pose both health and safety risks, while leftover ethanol can cause irritation in sensitive users. Regulated markets require residual solvent testing, but products from unregulated sources may not undergo any quality control.