CBD can be swallowed, held in the mouth, inhaled or put on the skin. The route changes how quickly it reaches the blood and how much of the dose gets there. Swallowing is by far the best studied route, and it is the one used by the registered CBD medicine.
How do the routes compare?
The share of a dose that reaches the bloodstream is called bioavailability. The table sets out what is known for each route. “Lawful availability” is the position as of November 2026.
| Route | Common forms | How fast | How much is absorbed | How well measured | Lawful availability in Australia |
|---|---|---|---|---|---|
| Swallowed (oral) | Oil, capsule, tablet, pastille | Slow. Blood levels peak in about 1 to 4 hours, or 2.5 to 5 hours with regular dosing.12 | About 6% on an empty stomach.3 About 4 times more total exposure with a high-fat meal.4 | Best studied route, but the 6% figure rests on limited data.1 The food effect is well measured.5 | Prescription only. Epidyolex is the one registered CBD-only medicine.6 A pharmacist-only category exists in law but has no approved product.78 |
| In the mouth (sublingual or oromucosal) | Drops under the tongue, spray, wafer, lozenge | Often said to be faster than swallowing. No reliable CBD figure. | Unknown. Estimates in one review ranged from about 12% to 35%.1 | Poorly. No absolute figure has been properly measured in people, and much of the dose is swallowed.91 | Prescription only. Sativex, a registered mouth spray, contains THC as well as CBD.6 The pharmacist-only category would cover this route, but has no approved product.78 |
| Inhaled | Vaporised dried flower or extract | Fast. Blood levels peak in 5 to 10 minutes.3 | About 31% when smoked (range roughly 11% to 45%).9 | The only route besides swallowing with a measured figure, and that figure comes from smoking, not vaporising.9 | Prescription only. Not eligible for the pharmacist-only category, which is limited to oral, oromucosal and sublingual products.7 |
| On the skin (topical or transdermal) | Cream, balm, gel, patch | Not established in people. | Low. CBD tends to stay in the outer layer of the skin.10 | Poorly. Most work is in the laboratory or in animals.10 | Prescription only. Not eligible for the pharmacist-only category.7 |
| Rectal or vaginal | Suppository, pessary | Not sourced. | Not sourced. | We found no human data to report. | Prescription only. Both appear on the TGA’s list of prescribed dosage forms.8 |
Why is so little swallowed CBD absorbed?
CBD dissolves in fat, not water, and it is heavily broken down by the gut wall and liver before it reaches the general circulation. This is called first-pass metabolism. On an empty stomach only about 6% of a swallowed dose gets through, and the amount varies a lot from person to person.3
Fat in a meal helps CBD dissolve and be absorbed. In one study of a single 1,500 mg dose, a high-fat meal raised the peak blood level 4.85 times and total exposure 4.2 times.5 The Australian product information for Epidyolex reports the same pattern (a five-fold rise in peak level and a four-fold rise in total exposure) and says the medicine should be taken the same way each time in relation to food.4
The practical point is that the same swallowed dose can give a several-times-different blood level depending on what was eaten with it. This applies to capsules, tablets and edible forms such as pastilles as much as to oil, because all of them are swallowed. See taking CBD with food.
Is under the tongue really better?
It is one of the most repeated claims about CBD oil, and it is not well supported.
The idea is sound in principle: a medicine absorbed through the lining of the mouth goes straight into the blood and skips the liver. For CBD, though, the measurements do not clearly show that happening. A review of CBD delivery noted that blood levels from a THC and CBD mouth spray were similar whether it was sprayed in the mouth or swallowed, and that the spray’s absorption changed with food, which should only happen if it is being swallowed. The authors concluded that CBD tends to sit in the lining of the mouth or be washed down with saliva.1
A systematic review of CBD studies in people found that inhaling was the only route, other than swallowing, with a properly measured figure.9 So “sublingual CBD is absorbed three or four times better” is a marketing statement, not a measured fact.
What about inhaling?
Inhaled CBD reaches the blood within minutes.3 The TGA notes that inhaled cannabis medicines take effect within 5 to 10 minutes, compared with about an hour when taken by mouth, and that this can matter for some patients, for example in palliative care.8
The same TGA paper lists the downsides. Vaping has been linked to a serious lung injury known as EVALI. Battery-powered devices have caused burns and explosions. Heating coils can release metals. And it is harder to measure a dose accurately.8 The paper also says oral forms, usually liquids, “may avoid effects on the respiratory system” and support accurate dosing.8 See CBD vapes and CBD flower.
What about creams and patches?
A cream is meant to act where it is applied. Very little CBD gets from the skin to the blood, because CBD is so fat-loving that it collects in the outer layer of the skin instead of passing through.10 Researchers are testing patches, gels and tiny carrier particles to push more through, but that work is mostly preclinical.10 See CBD creams and topicals.
Does the route change what CBD does?
No trial has shown that one route makes CBD work better for a condition. Almost all of the clinical trials, including the epilepsy trials behind the registered medicine, used swallowed CBD.2 The TGA says there is “limited evidence to support the safety and efficacy” of other dosage forms such as sprays, suppositories, topicals and edibles.8
A faster route is also not automatically a stronger one. In a trial of vaporised cannabis for migraine attacks, CBD on its own was no better than placebo on any measure at two hours.11
What forms can be prescribed in Australia?
When a prescriber applies to supply an unapproved cannabis medicine, the TGA’s system offers 19 dosage forms. They include capsules, tablets, chewable tablets, oral liquids, lozenges, pastilles, wafers, sprays, dried herb for vaporising, inhalations, topicals, skin patches, pessaries and suppositories. The TGA says no ongoing clinical assessment is made of the risks of each form. The choice is the prescriber’s, based on clinical need.8
That list covers all cannabis medicines, including those with THC. Whatever the form, a CBD product needs a prescription. See how legal access to CBD works.
Safety points that apply to every route
- CBD can cause sleepiness, diarrhoea and reduced appetite, and it interacts with a number of medicines.2 See CBD side effects and CBD drug interactions.
- A product that contains any THC can cause a positive roadside or workplace drug test, however it is taken. See CBD and driving and CBD and drug tests.
- Do not change the form or the way you take a prescribed product without asking your prescriber. Because absorption differs so much between routes, a dose by one route is not equal to the same dose by another.
Footnotes
-
Millar SA, Maguire RF, Yates AS, O’Sullivan SE. Towards better delivery of cannabidiol (CBD). Pharmaceuticals, 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7558665/ ↩ ↩2 ↩3 ↩4 ↩5
-
US National Library of Medicine, DailyMed. Epidiolex (cannabidiol) oral solution prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8bf27097-4870-43fb-94f0-f3d0871d1eec ↩ ↩2 ↩3
-
World Health Organization, Expert Committee on Drug Dependence. Cannabidiol (CBD) critical review report, 2018. https://cdn.who.int/media/docs/default-source/controlled-substances/whocbdreportmay2018-2.pdf ↩ ↩2 ↩3 ↩4
-
Therapeutic Goods Administration. Epidyolex (cannabidiol) Australian Product Information, version published with the AusPAR, January 2021 (may have been superseded). https://www.tga.gov.au/sites/default/files/auspar-cannabidiol-210115-pi.pdf ↩ ↩2
-
Taylor L, et al. Phase I trial of highly purified cannabidiol in healthy volunteers, including the effect of food. CNS Drugs, 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6223703 ↩ ↩2
-
NPS MedicineWise. Medicinal cannabis: what you need to know. https://www.nps.org.au/professionals/medicinal-cannabis-what-you-need-to-know ↩ ↩2
-
Australian Government. Therapeutic Goods (Poisons Standard, October 2026) Instrument 2026, Schedule 3 and Schedule 4 cannabidiol entries. https://www.legislation.gov.au/F2026L01327/asmade/2026-09-30/text/original/pdf ↩ ↩2 ↩3 ↩4
-
Therapeutic Goods Administration. Consultation: Reviewing the safety and regulatory oversight of unapproved medicinal cannabis products, version 1.0, August 2025. https://consultations.tga.gov.au/medicines-regulation-division/test-soms/user_uploads/final---consultation-paper---medicinal-cannabis-review---august-2025.pdf ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8
-
Millar SA, et al. Systematic review of the pharmacokinetics of cannabidiol in humans, 2018. https://pubmed.ncbi.nlm.nih.gov/30534073/ ↩ ↩2 ↩3 ↩4
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Lefebvre È, Tawil N, Yahia L. Transdermal delivery of cannabidiol for the management of acute inflammatory pain: a comprehensive review of the literature. International Journal of Molecular Sciences, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC11172078/ ↩ ↩2 ↩3 ↩4
-
Schuster NM, et al. Vaporised cannabis versus placebo for acute migraine, randomised controlled trial (University of California San Diego). https://escholarship.org/uc/item/89m6r4pt ↩
Common questions
What is the best way to take CBD?
There is no single best way, and this site does not recommend one. Swallowed oil is the route used in almost all the clinical trials and by the registered CBD medicine. Inhaled CBD works faster but exposes the lungs. A prescriber chooses the form to suit the person and the condition.
Is CBD under the tongue better absorbed than swallowed CBD?
It is often claimed, but it has not been properly measured in people. Estimates vary widely and studies suggest much of a dose given in the mouth is swallowed anyway. Taking swallowed CBD with a fatty meal has a much larger, proven effect on absorption.
Which form of CBD works fastest?
Inhaled CBD. Blood levels peak within about 5 to 10 minutes, compared with hours for a swallowed dose. Faster does not mean more effective, and vaping devices have been linked to lung injury, burns and exposure to metals.
Does CBD cream get into the bloodstream?
Very little does. CBD is so fat-loving that it tends to stay in the outer layer of the skin rather than pass through. Patches and gels are being designed to push more through, but that work is mostly at the laboratory and animal stage.
This page is general information, not medical or legal advice. Laws and evidence change; we show the date we last checked the facts at the top of every page. Talk to your doctor or pharmacist before starting, stopping or changing any medicine.
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