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How CBD is extracted and made

From plant to bottle. How CBD is extracted with CO2, ethanol or other solvents, what decarboxylation is, what residues can remain and what Australia requires.

Facts checked 13 November 20267 min readHow we research

CBD is extracted from the cannabis plant with a solvent, most often pressurised carbon dioxide or ethanol, then refined and blended into a finished product. The method affects what else ends up in the extract and what residues need to be tested for. No method has been shown to make CBD work better in people.

Where does CBD come from?

CBD is one of many cannabinoids made by the cannabis plant. Hemp-type plants produce much less THC and more CBD than plants grown for their intoxicating effect.1 See the cannabis plant.

The plant does not make CBD directly. It makes cannabidiolic acid (CBDA). CBD forms when CBDA loses part of its structure, a reaction called decarboxylation.1 Heat drives it. In one extraction study, temperatures above 130 °C converted more than 99% of the acid cannabinoids to their neutral forms.2 The same reaction turns THCA into THC.

Step 1: Growing, harvesting and drying

The flowers are harvested and dried before extraction. Drying has to be controlled. A review of cannabis processing notes that the wrong conditions can cause unwanted decarboxylation and loss of terpenes (the aromatic oils), and that light, oxygen and heat can degrade cannabinoids.2

What the plant took up while growing also matters, which is why Australian rules set limits for pesticides, heavy metals and mould toxins in the plant used to make medicines (see below).

Step 2: Extraction

Extraction means dissolving the cannabinoids out of the plant material. The review lists a long menu of solvents that have been used, including ethanol, butane, propane, hexane, carbon dioxide and olive oil.2 The three most discussed are compared here.

Method How it works Advantages reported Drawbacks reported
Supercritical carbon dioxide (CO2) CO2 is held above 31 °C and about 74 bar, where it is neither a normal liquid nor a gas and behaves like a solvent for oily compounds Non-flammable, non-toxic, inert, easy to remove. Low temperature protects heat-sensitive compounds. Pressure and temperature can be tuned to target what is extracted Higher pressure increases yield but reduces selectivity. Ethanol is sometimes added as a co-solvent
Ethanol Plant material is soaked or washed in alcohol High yields Also extracts chlorophyll, which adds a green colour and unpleasant taste. Removing it with activated charcoal can cut cannabinoid content by about half
Hydrocarbon gases (butane, propane) The gas is cooled or pressurised into a liquid and passed through the plant material, then evaporated off Solvent boils off at low temperature Flammable and potentially explosive. Industrial-grade gas can carry impurities into the extract, and the solvent itself can remain as a residue

All of the entries in the table come from the same narrative review of cannabis processing methods.2

Two other approaches are worth knowing. Soaking the plant in a vegetable oil such as olive oil is simple, non-flammable and good at capturing terpenes, but the extract cannot be concentrated by evaporating the oil. And petroleum solvents such as naphtha have left significant hydrocarbon residues in extracts in testing, which is why the review says special attention to residues is needed.2

Pressurising flammable gases is hazardous.2 This page describes industrial processes, not a method to try.

Step 3: Refining

The first extract is a dark, sticky mixture of cannabinoids, terpenes, plant waxes and pigments. How far it is refined determines the type of product.

  • A full-spectrum product keeps the plant’s mix of cannabinoids, including some THC.
  • A broad-spectrum product has had the THC removed.
  • An isolate is CBD purified until nothing else remains. Pure CBD is a crystalline solid with a melting point of 62 to 63 °C. The World Health Organization’s review describes a pharmaceutical CBD “extracted from hemp plants through a multi-stage process into a crystalline powder”.1

Industry descriptions of refining mention steps such as chilling the extract to remove waxes (winterisation), distillation and chromatography. We could not confirm the details of those steps from an authoritative source, so we do not describe them further here.

See full spectrum vs broad spectrum vs isolate.

Step 4: Formulating the product

The extract or isolate is then made into something a person can take. For an oil, that means dissolving it in a carrier. Epidyolex, the registered CBD medicine, contains 100 mg of CBD per millilitre in sesame oil with 10% ethanol by volume, a sweetener and a flavour.3 Capsules, sprays, creams and other forms each need their own inactive ingredients. See ways to take CBD compared.

Can CBD be made without the plant?

Yes. CBD can be made by chemical synthesis, and the World Health Organization’s review describes published synthetic routes and a synthetic pharmaceutical CBD.1

Australian rules treat the two sources differently:

  • Medicinal cannabis standard (TGO 93). Each active ingredient and other cannabinoid must be “from the cannabis plant”, and its chemical structure must not be “modified or transformed in any way”. Decarboxylation of the natural acid forms does not count as modification.4
  • Pharmacist-only schedule entry. The Schedule 3 entry for low-dose CBD allows CBD that is “either plant derived or, when synthetic, only contains the (-)-CBD enantiomer”, which is the same form of the molecule the plant makes.5 No product has been approved under this entry as of November 2026.

What residues can extraction leave behind?

Solvents. International medicine guidelines (ICH Q3C) sort solvents into three classes:6

Class Meaning Examples
1 Solvents to be avoided: known or strongly suspected human carcinogens and environmental hazards Benzene
2 Solvents to be limited because of other significant toxicity Hexane, methanol, xylene
3 Solvents with low toxic potential Ethanol

Class 3 solvents have a permitted daily exposure of 50 mg or more. The guideline’s limit for hexane, a Class 2 solvent, is 290 parts per million.6

Residues are not a theoretical worry. In a 2024 United States study of 202 CBD products bought online, residual solvents were detected in 181. Hexane, xylenes and methanol were found at the highest concentrations, though only about 1% of results exceeded a regulatory threshold.7

Contaminants from the plant. The same study found heavy metals in 44 of 202 products, most often lead, and pesticides in 30.7 Whatever the extraction method, the finished product is what needs testing.

What do Australian rules require of manufacturers?

Unapproved medicinal cannabis products supplied in Australia must comply with TGO 93.8 Among other things it requires:4

  • Identification. The plants used must be positively identified by examination with the naked eye, under a microscope and by chromatography.
  • Contaminant limits for the plant material. Limits apply to aflatoxins and ochratoxin A (mould toxins), arsenic, cadmium, lead and mercury, pesticides, foreign matter and total ash.
  • No ethylene oxide. Any decontamination treatment must not use it or harm product quality.
  • No adulteration. Nothing may be added or substituted that is not part of the formulation, other than a processing aid.
  • Good Manufacturing Practice (GMP). For products released since 1 July 2023, each manufacturing step overseas must meet a recognised GMP standard, with evidence such as a GMP certificate from a listed regulator.
  • Content. The finished product must contain 90% to 110% of the stated amount of each active ingredient (80% to 120% for herbal products such as dried flower).

The TGA says GMP became mandatory for both domestic and overseas manufacturers in 2023, and that it checks compliance by risk-based surveillance testing, not by testing every product.8

These rules apply to medicines supplied lawfully in Australia. They do not apply to products sold by overseas websites. See quality standards for Australian CBD products and how to read a certificate of analysis.

Does the extraction method matter to you?

Marketing often presents one method, usually CO2, as proof of quality. The method tells you which residues are possible. It does not tell you whether a particular batch is clean or correctly labelled. Only batch testing does that. And no clinical trial has compared products made by different extraction methods, so there is no evidence that the method changes what CBD does.

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 ↩3 ↩4

  2. Lazarjani MP, Young O, Kebede L, Seyfoddin A. Processing and extraction methods of medicinal cannabis: a narrative review. Journal of Cannabis Research, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8290527/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. 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 ↩

  4. Australian Government. Therapeutic Goods (Standard for Medicinal Cannabis) (TGO 93) Order 2017, compilation of 6 December 2022, sections 8 to 13 and 17 and Schedule 1. https://www.legislation.gov.au/F2017L00286/latest/text ↩ ↩2

  5. Australian Government. Therapeutic Goods (Poisons Standard, October 2026) Instrument 2026, Schedule 3 cannabidiol entry. https://www.legislation.gov.au/F2026L01327/asmade/2026-09-30/text/original/pdf ↩

  6. International Council for Harmonisation. ICH Q3C(R8) Impurities: guideline for residual solvents, 2021. https://database.ich.org/sites/default/files/ICH_Q3C-R8_Guideline_Step4_2021_0422_1.pdf ↩ ↩2

  7. 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/ ↩ ↩2

  8. 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

Common questions

How is CBD oil made?

The cannabis plant is grown, dried and heated to convert its CBDA into CBD. A solvent such as pressurised carbon dioxide or ethanol dissolves the cannabinoids out of the plant. The solvent is removed, the extract is refined to the purity wanted, and the result is blended with a carrier oil and tested.

Is CO2 extraction better than ethanol extraction?

Each has trade-offs. Carbon dioxide is non-flammable and non-toxic and is easy to remove from the extract. Ethanol gives high yields but also pulls out chlorophyll, which then has to be removed. No study shows that the extraction method changes how CBD works in people. What matters is that the finished product is tested.

What is decarboxylation?

It is the conversion of CBDA, the acid form of CBD made by the plant, into CBD. Heat drives the change. The same process turns THCA into THC. Australian rules do not treat it as chemically modifying the cannabinoid.

Can CBD be made synthetically?

Yes. The World Health Organization notes that CBD can be produced by chemical synthesis as well as extracted from plants. Australia's quality standard for medicinal cannabis requires cannabinoids to come from the cannabis plant, while the pharmacist-only schedule entry would allow one specific form of synthetic CBD in a registered product.

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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