Cannabis bioavailability — what actually arrives
The label says 10 mg CBD. But how much ends up in the blood? Anywhere from 0.4 to 3.5 mg — depending on the route.
Bioavailability = fraction of dose reaching systemic circulation. Inhaled 20–35 %, sublingual 15–20 %, oral 4–20 %, rectal 50–70 %, transdermal < 1 %.
What bioavailability means
Fraction of an administered dose reaching systemic circulation unchanged. IV = 100 % reference.
Cannabinoids are highly lipophilic and undergo first-pass metabolism when swallowed.
By route
Inhalation: 20–35 %. Peak 3–10 min.
Sublingual: 15–20 %. Peak 60–90 min.
Practical implications
10 mg CBD sublingual ≈ 2 mg systemic.
10 mg CBD oral ≈ 0.5–2 mg systemic depending on stomach.
Nano and liposomal formulations
Nano-emulsions (< 100 nm) and liposomes package cannabinoids in water-like vehicles — 2–5× higher oral bioavailability.
Found in cannabis drinks and some premium oils. Price premium is significant.
FAQ
Why do edibles last longer despite lower bioavailability?
11-OH-THC has a longer half-life.
Does food change CBD oil bioavailability?
Yes, fat ×4 orally (Birnbaum 2019). Sublingual is unaffected.
Are CBD creams a waste?
No — locally effective, systemically poor.
Why is oral so variable?
CYP enzyme variants plus stomach contents plus carrier oil.