Weed is a slang name for cannabis
Weed refers to the dried flower, leaves, and stems of plants in the genus Cannabis. Marijuana, pot, bud, ganja, and grass are other names for the same material. The plant holds more than 100 compounds called cannabinoids. The two with the most research are delta-9 THC (tetrahydrocannabinol) and CBD (cannabidiol).
THC, CBD, and hemp
THC binds CB1 receptors in the brain and causes intoxication. CBD does not bind those receptors the same way and does not cause a high. Both compounds appear in the same plant at different ratios.
US law separates hemp from marijuana with one number. Hemp is Cannabis sativa L. with delta-9 THC at or below 0.3 percent on a dry weight basis. Plant material above that threshold is marijuana under federal law. The 2018 Farm Bill set that line and removed hemp from the Controlled Substances Act.
- Hemp: delta-9 THC at or below 0.3 percent dry weight. Legal as an agricultural commodity under federal law.
- Marijuana: delta-9 THC above 0.3 percent. Schedule I under federal law.
- State rules differ. Some states allow medical use, adult use, or both. Others do not.
Potency has changed
THC levels in cannabis flower rose over the past 30 years. NIDA tracks seized samples and reports average delta-9 THC near 15 percent in recent years, up from under 4 percent in the early 1990s. CBD products sold online often hold 0.3 percent THC or less, but labels can be wrong.
How people use it
Methods include smoking the flower, vaporizing, edibles, tinctures, and topicals. Smoking and vaping deliver THC to the brain in minutes. Edibles take 30 to 60 minutes or more.
Risks and drug interactions
Smoke from cannabis contains tar and carbon monoxide, per CDC. High THC doses can cause anxiety, fast heart rate, and paranoia. CBD can interact with drugs that use the CYP450 enzyme system, including some blood thinners and seizure medicines. Epidiolex, a prescription CBD drug, carries warnings about liver injury and interactions.
Lab tests on CBD products
A certificate of analysis (COA) from an independent lab lists what a batch contains. Look for:
- Cannabinoid potency: CBD, THC, and minor cannabinoids.
- Pesticides and residual solvents.
- Heavy metals: lead, arsenic, cadmium, mercury.
- Microbials and mycotoxins.
- A batch number that matches the product label.
Federal status of CBD
The FDA has not approved CBD as a dietary supplement or a food ingredient. It has approved one CBD medicine, Epidiolex, for two rare seizure conditions. The FDA states that some CBD products carry claims not supported by evidence, and the agency has issued warning letters for such claims.
What is unknown
Long-term effects of daily CBD use in healthy adults are not well documented. Rules for hemp-derived products vary by state, and no federal standard exists for testing or labeling. Check state law and ask for a COA before buying.