7 evidence-graded facts. Click any card for the full summary and sources.
THC metabolites are fat-soluble and linger for days (occasional use) to weeks (daily use) in urine. Roadside and workplace tests detect exposure, not impairment — one of the hardest unsolved problems in cannabis policy.
Consumption & Dosing STRONG EVIDENCEPeak effects from edibles arrive far later than smoking (minutes). The classic bad experience is re-dosing at minute 45 because "nothing happened" — then both doses land together. The single most protective rule with edibles is: wait two full hours before taking more.
Consumption & Dosing MODERATE EVIDENCEVaporizers heat cannabis below combustion, and studies show drastically reduced carbon monoxide and tar byproducts versus smoking, with similar THC delivery. "Reduced harm" is accurate; "harmless" is not — long-term data is thin, and vape liquids are a separate, riskier category.
Consumption & Dosing STRONG EVIDENCEStudies sealing non-smokers in small unventilated chambers with heavy smoke produced detectable THC metabolites and mild effects. In ventilated real-world conditions, positives were rare and below standard testing thresholds. The "contact high" is real but requires genuinely extreme exposure.
Consumption & Dosing STRONG EVIDENCEAdverse effects of THC — anxiety, tachycardia, dizziness, impairment — scale with dose and peak blood level, and edibles add unpredictable absorption on top. Starting at 2.5–5 mg and waiting the full onset window before redosing is how you stay on the friendly side of the curve.
Consumption & Dosing MODERATE EVIDENCECombustion destroys a share of THC, sidestream smoke carries away more, and exhalation loses the rest — classic smoking-dynamic studies estimate roughly a fifth to a third reaches the smoker. Potency on the label is not potency in the blood.
Consumption & Dosing STRONG EVIDENCEChronic cannabis use downregulates CB1 receptors, a biological basis of tolerance. PET imaging studies show cortical CB1 availability rebounding toward normal after about four weeks of abstinence. Tolerance is real — and so is its reversal.
Consumption & Dosing