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Full spectrum vs broad spectrum vs isolate

What full spectrum, broad spectrum and isolate mean, how Australian law sorts them, what the evidence says and why the choice matters for drug tests.

Facts checked 13 November 20267 min readHow we research

Isolate is CBD on its own. Broad spectrum is CBD with other plant compounds but the THC taken out. Full spectrum is a whole-plant extract that keeps some THC. No good trial shows one type works better than another. The difference that is proven is that full-spectrum products can cause a positive drug test.

What do the three terms mean?

Term What it contains THC
Isolate CBD only. Pure CBD is a crystalline solid, usually dissolved in a carrier oil.1 None intended
Broad spectrum CBD plus other cannabinoids and terpenes from the plant Removed
Full spectrum (also “whole plant”) The extract with its natural mix of cannabinoids and terpenes Some

Cannabinoids are the family of compounds that includes CBD and THC. Terpenes are the oils that give the plant its smell. See other cannabinoids and terpenes.

These are industry words. They are not defined in Australian law, and nothing stops two makers using them differently.

How does Australian law sort these products?

The law does not use “spectrum” language. It looks at what share of the cannabinoids in a product is CBD.

A product counts as a Schedule 4 (prescription only) CBD medicine when CBD makes up 98% or more of its total cannabinoid content, and any other cannabinoids are ones naturally found in cannabis and make up 2% or less.2 An isolate fits that definition. So does an extract in which other cannabinoids are present only in traces.

Once other cannabinoids pass 2% of the total, the product is no longer covered by the CBD entries. It falls under the cannabis and THC entries and is handled as a Schedule 8 controlled drug. That is where most products sold overseas as “full spectrum” would land.2 This reading comes from putting the schedule entries side by side, not from a single sentence in the law.

The TGA groups prescribed cannabis medicines into five categories on the same basis:34

TGA category Name CBD as a share of total cannabinoids Schedule
1 CBD medicinal cannabis product 98% or more 4
2 CBD-dominant 60% to under 98% 8
3 Balanced 40% to under 60% 8
4 THC or other cannabinoid dominant 2% to under 40% 8
5 THC or other cannabinoid Under 2% 8

Two things follow. First, only Category 1 is “CBD only” in the legal sense. A “CBD-dominant” Category 2 oil is a controlled drug and can contain a meaningful amount of THC. Second, even a Category 1 product is allowed up to 2% other cannabinoids, so it is not guaranteed to be THC-free. Victoria’s driving fact sheet for patients makes the same point: some medicines that are mostly CBD “may also contain very small amounts of THC”.5

See Schedule 3, 4 and 8 explained.

Does full spectrum work better?

This is the claim behind the “entourage effect”: that cannabinoids and terpenes work better together than CBD does alone. It is a reasonable idea that has not been shown in controlled human trials.

  • No head-to-head trial has shown full spectrum beating isolate for any condition.
  • The strongest evidence for CBD is for a purified product. The epilepsy trials that led to a registered medicine used highly purified CBD.6
  • Laboratory tests of terpenes have mostly been negative. In two studies, common cannabis terpenes did not activate the body’s cannabinoid receptors or change how THC or CBD acted on them.78
  • The human study usually quoted in favour was not a fair test. It pooled observational reports from people with treatment-resistant epilepsy and found more reported improvement on CBD-rich extracts (71%) than on purified CBD (37%). The studies were not randomised and differed in patients and in how improvement was defined.9
  • One small pilot points the other way. In 44 people with alcohol use disorder, 150 mg a day of a full-spectrum product reduced craving more than a broad-spectrum product or placebo. The sample was small and the result needs repeating.10

A 2023 scoping review concluded that the literature “provides limited evidence” for the entourage effect and warned against promoting it as proven.11 See the entourage effect.

Why does the type matter for drug tests?

Roadside and workplace drug tests look for THC or its breakdown products, not CBD. Whether a CBD product puts you at risk therefore depends on how much THC comes with it.

  • Pure CBD. In a study of oral and vaporised pure CBD (100 mg), only 1 of 218 urine samples screened positive at the lowest cut-off, and none was confirmed positive.12
  • Full spectrum. Fourteen patients took a full-spectrum, high-CBD extract containing 0.02% THC for four weeks. The authors concluded that people using full-spectrum hemp products “may have positive test results” for the THC breakdown product on a urine drug screen.13
  • Broad spectrum. In a study of a broad-spectrum product taken for two weeks, no THC or THC breakdown products were detectable in urine.14

That last result depends on the THC really having been removed. In a study of 80 unregulated United States products, 21 were labelled “THC-free” and 5 of those contained measurable THC.15

Anyone who drives, is tested at work or competes in sport should treat a full-spectrum product as a THC product. See CBD and drug tests, CBD and driving and CBD and sport.

Can you trust the word on the label?

Not always, at least for unregulated products. A 2024 study tested 202 CBD products bought online in the United States. Of those making a type claim (84 full spectrum, 28 broad spectrum, 37 isolate), 26% did not meet the definition of the type named on the pack.16

Prescription products in Australia are held to a quality standard. Under it, any THC that reaches 1.0% of the product, and any other cannabinoid that reaches 2.0%, is treated as an active ingredient whether or not the maker declares it, and the label must state the amount of each active ingredient.17 See how to read a CBD label and how to read a certificate of analysis.

What should you ask your prescriber?

This site does not recommend a type. If you have been prescribed a CBD product, useful questions are:

  • Which TGA category is this product in, and is it Schedule 4 or Schedule 8?
  • How much THC does it contain per millilitre or per dose?
  • Could it affect a roadside, workplace or sporting drug test?
  • Is there a reason to choose this type over a CBD-only product?

Products containing THC bring extra cautions around driving, pregnancy and mental health. See CBD vs THC and who should not take CBD?

Footnotes

  1. 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. Australian Government. Therapeutic Goods (Poisons Standard, October 2026) Instrument 2026, cannabidiol, cannabis and tetrahydrocannabinols entries. https://www.legislation.gov.au/F2026L01327/asmade/2026-09-30/text/original/pdf ↩ ↩2

  3. Penington Institute. Cannabis in Australia, November 2025 (restating the TGA category scheme). https://www.penington.org.au/wp-content/uploads/2025/11/Penington_Institute_Cannabis-in-Australia_Nov_2025.pdf ↩

  4. Therapeutic Goods Administration. Medicinal cannabis. https://www.tga.gov.au/products/unapproved-therapeutic-goods/medicinal-cannabis ↩

  5. Victorian Government. Medicinal cannabis and driving: patient fact sheet. https://edge.sitecorecloud.io/stategovernc45d-cftw-production-c9ca/media/Project/TransportWebsite/Forms/medicinal-cannabis-and-driving-patient-factsheet.pdf ↩

  6. 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 ↩

  7. Santiago M, et al. Laboratory study of six common cannabis terpenes at CB1 and CB2 receptors, 2019. https://pubmed.ncbi.nlm.nih.gov/31559333/ ↩

  8. Finlay DB, et al. Terpenoids from cannabis do not mediate an entourage effect by acting at cannabinoid receptors, 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109307/ ↩

  9. Review discussing Pamplona et al. 2018, observational meta-analysis of CBD-rich extracts and purified CBD in treatment-resistant epilepsy. https://pmc.ncbi.nlm.nih.gov/articles/PMC10821245/ ↩

  10. Pilot randomised trial of full-spectrum and broad-spectrum hemp CBD (150 mg a day) in alcohol use disorder. https://pmc.ncbi.nlm.nih.gov/articles/PMC12066606 ↩

  11. Scoping review of the entourage effect, 2023. https://pubmed.ncbi.nlm.nih.gov/37535820/ ↩

  12. Study of urinary drug testing after oral and vaporised cannabidiol and vaporised CBD-dominant cannabis. https://pubmed.ncbi.nlm.nih.gov/31682266/ ↩

  13. Dahlgren MK, et al. Urine THC testing after four weeks of a full-spectrum, high-cannabidiol extract. JAMA Psychiatry, 2021. https://pubmed.ncbi.nlm.nih.gov/33146684/ ↩

  14. Study of urine drug testing after two weeks of a broad-spectrum CBD product. https://pubmed.ncbi.nlm.nih.gov/39509209/ ↩

  15. Johnson E, Kilgore M, Babalonis S. Cannabidiol (CBD) product contamination: quantitative analysis of delta-9-THC concentrations found in commercially available CBD products. Drug and Alcohol Dependence, 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9899037/ ↩

  16. Gidal BE, et al. Product labeling accuracy and contamination analysis of commercially available cannabidiol product samples. Frontiers in Pharmacology, 2024. https://pmc.ncbi.nlm.nih.gov/articles/PMC10982813/ ↩

  17. Australian Government. Therapeutic Goods (Standard for Medicinal Cannabis) (TGO 93) Order 2017, compilation of 6 December 2022, sections 4 and 15. https://www.legislation.gov.au/F2017L00286/latest/text ↩

Common questions

What is the difference between full spectrum, broad spectrum and isolate CBD?

Isolate contains only CBD. Broad spectrum contains CBD plus other cannabinoids and terpenes from the plant, with THC removed. Full spectrum is a whole-plant extract that keeps a small amount of THC. The words are marketing terms and have no legal definition in Australia.

Is full-spectrum CBD better than isolate?

Nobody has shown that in a proper trial. The idea that plant compounds work better together is called the entourage effect, and reviews describe the evidence for it as limited. The CBD medicine with the strongest evidence, for certain epilepsies, is a purified product.

Will full-spectrum CBD show up on a drug test?

It can. Drug tests look for THC, and full-spectrum products contain some. In a small study, people taking a full-spectrum, high-CBD extract for four weeks produced positive urine tests for the THC breakdown product. Pure CBD has not caused confirmed positive tests in studies.

Is full-spectrum CBD legal in Australia?

Only on prescription, and it is usually classed more strictly than CBD-only products. If cannabinoids other than CBD make up more than 2% of the cannabinoid content, the product falls outside the CBD entries in the Poisons Standard and is treated as a Schedule 8 controlled drug.

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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