Finding an effective CBD dose isn’t just about the milligrams on the label—it’s also about bioavailability: how much CBD actually reaches your bloodstream and how fast. Below, we explain CBD bioavailability in plain English, compare absorption by method, and share simple ways to make your CBD work harder for you.
What is CBD bioavailability?
Bioavailability is the proportion of an ingredient that’s absorbed into your bloodstream and available for your body to use. Two identical doses can feel very different if one route delivers more CBD, more quickly, than another.
Because CBD can be taken as drops, capsules, edibles, vapes, balms and more, the route of administration is the single biggest driver of bioavailability.
Quick explainer video: CBD bioavailability overview
CBD half-life: how long it lasts
Half-life is how long it takes for the amount of CBD in your body to drop by half. Human studies suggest oral CBD typically has a half-life around ~1–2 days. That helps explain why consistent daily use often gives steadier results than one-off doses.
Read more: How long CBD takes to work
How much CBD oil should I take?
Your ideal dose depends on body size, experience, product type and timing. A practical approach:
- Start low: 10–15 mg/day for 3–7 days.
- Titrate slowly: increase by 1–5 mg/day until you reach desired effects.
- Track how you feel (1–10) to find your personal “sweet spot”.
- UK FSA guidance: healthy adults should not exceed 70 mg/day.
Read more: CBD dosage guide
How is CBD best absorbed? (by method)
Oral (edibles, drinks, capsules)
Easy and convenient, but CBD must pass through digestion and first-pass metabolism in the liver. Expect lower bioavailability and a slower onset.
- Typical bioavailability: ~6–20%
- Onset: ~45–90+ minutes
- Tip: take with a meal containing healthy fats to improve uptake.
Read more: Cooking with CBD oil
Sublingual (oil drops & sprays under the tongue)
Holding CBD under the tongue lets some absorb directly through oral tissues into the bloodstream, bypassing part of digestion.
- Typical bioavailability: ~13–35% (varies with technique/formula)
- Onset: ~15–45 minutes
- How to: hold under the tongue 60–120 seconds before swallowing; take with food for added boost.
Inhalation (vaping)
Delivers CBD via the lungs directly to the bloodstream—fast and relatively efficient compared with oral routes.
- Typical bioavailability: ~30–50%+
- Onset: ~5–15 minutes (fastest)
- Note: use CBD vape e-liquid; do not vape standard tincture oils.
Read more: Can you vape CBD oil?
Topicals (balms, creams) vs. Transdermals (patches)
Topicals act locally (skin, joints, superficial muscles) and usually do not deliver meaningful CBD to the bloodstream—great for targeted areas, not systemic effects.
Transdermal patches are designed to push CBD through the skin barrier for systemic delivery; bioavailability varies by formulation.
Read more: CBD oil for skin
Intravenous (IV)
Nearly 100% bioavailable but medical-only—not a practical consumer route.
How to increase CBD bioavailability
- Pair with fats: Take CBD with a meal rich in healthy fats (e.g., avocado, nuts, olive oil). MCT oil is a common carrier that supports absorption.
- Use good sublingual technique: Hold drops under the tongue for 60–120 seconds; avoid rinsing immediately after.
- Pick the right format for your goal: Vape for speed, sublingual for balanced speed/efficiency, capsules/edibles for convenience and steady daily intake.
- Consider emulsified/nano formulations: These break CBD into smaller particles that may disperse better in digestive fluids.
- Leverage the entourage: Broad- or full-spectrum formulas (cannabinoids + terpenes) may support overall effectiveness. Terpenes like limonene, linalool, myrcene and beta-caryophyllene are commonly used in hemp extracts.
- Piperine (black pepper extract): Often used in supplements to enhance absorption of certain compounds; some CBD formulas include it.
Read more: What are terpenes? · CBD brownies
Key factors that affect absorption
- Fasted vs. fed: Taking CBD with food—especially fats—can markedly increase exposure versus an empty stomach.
- Dose & tissue saturation: Raising the dose generally raises exposure, but benefits plateau once tissues are saturated.
- Health status & meds: Liver function and some medications can change how CBD is processed. Speak to a healthcare professional if you take prescription meds or have medical conditions.
- Formulation & processing: Carrier oil (e.g., MCT), added emulsifiers, and heating processes can influence absorption.
Read more: CBD & liver · How to take CBD
FAQ
How much CBD is absorbed sublingually?
Estimates vary by person and product, but holding drops under the tongue typically yields about 13–35% bioavailability when technique is consistent.
What method gives the highest bioavailability I can use at home?
Vaping is generally the highest and fastest consumer method (~30–50%+). Sublingual is a strong second with fewer equipment needs.
Can I just take more CBD instead of optimising bioavailability?
Higher doses can help to a point, but you may get better results (and better value) by improving absorption—e.g., with food, technique, and the right format.
Does topical CBD enter the bloodstream?
Most topicals are designed for local effects and don’t deliver meaningful systemic CBD. Transdermal patches are formulated to do so.
Is CBD a medicine?
Over-the-counter CBD in the UK is sold as a food supplement, not a medicine. It is not intended to treat, cure, or prevent disease.
Final thoughts on CBD bioavailability
For most people, the best balance of effectiveness, speed and simplicity is sublingual oil taken with food, using good technique. If you need faster onset, consider vaping; for convenience and habit-building, capsules or edibles are great—just pair them with dietary fats. Whatever you choose, start low, titrate slowly, and be consistent.
