The hemp extraction process separates cannabinoids such as CBD, together with terpenes, from the resin glands of the dried plant. The main industrial methods are supercritical CO₂ extraction, ethanol extraction and hydrocarbon extraction; simpler methods use oil or physical separation. The crude extract is then refined, for example by winterisation and distillation, and tested before it goes into a product.
Key facts
- What is extracted
- Cannabinoids and terpenes from the trichomes (resin glands) on the flowers and leaves
- Main methods
- Supercritical CO₂, ethanol, hydrocarbons (butane, propane), oil infusion and solventless methods
- Most common in research
- Solvent extraction (Lazarjani et al., 2021)
- After extraction
- Winterisation, filtration, solvent removal and often distillation; then laboratory testing
- UK rule
- Hemp leaves and flowers are controlled parts of the plant; licensed UK hemp farms may only use seeds and fibre (Home Office, as of October 2026)
Prefer watching? This video covers the key points:
What is hemp extraction?
Cannabinoids and terpenes are made in the trichomes, tiny resin glands that cover the flowers and upper leaves of the plant. Extraction dissolves or separates that resin from the rest of the plant material. The result is a concentrated extract that can be refined into CBD oil, distillate or isolate.
Many different solvents can dissolve cannabinoids, including ethanol, butane, propane, hexane, carbon dioxide and olive oil. A review of 81 relevant papers found that solvent extraction is the most common method for cannabis (Lazarjani et al., 2021).
What are the main hemp extraction methods?
| Method | Solvent | Strengths | Drawbacks |
|---|---|---|---|
| Supercritical CO₂ | Carbon dioxide under pressure | No toxic solvent residue; conditions can be tuned to target different compounds | Expensive equipment; needs skilled operators |
| Ethanol | Alcohol, often chilled | Fast and scalable | Also pulls out chlorophyll and other plant material, so more refining is needed |
| Hydrocarbon | Butane or propane | Keeps a rich terpene profile; avoids chlorophyll and water | Flammable, potentially explosive gases; risk of solvent residue |
| Oil infusion | A carrier oil such as olive oil | Simple, no special solvent | Low cannabinoid concentration |
| Solventless | None (sieving, ice water, pressure) | No solvent at all | Hard to scale; less studied |
How does CO₂ extraction work?
Above a certain temperature and pressure, carbon dioxide becomes supercritical: it flows like a gas but dissolves compounds like a liquid. The CO₂ passes through the ground plant material and dissolves cannabinoids and terpenes. When the pressure drops, the CO₂ turns back into a gas and leaves the extract behind, and it can be captured and reused. Reviewers describe supercritical fluid extraction as a greener approach that reduces toxic residue on products (Lazarjani et al., 2021). By changing pressure and temperature, operators can also shift which compounds the CO₂ picks up. Our page What is CO₂ extraction? covers the method in more detail.
How does ethanol extraction work?
The plant material is soaked in ethanol, which dissolves the cannabinoids, and the ethanol is then evaporated off. Ethanol also dissolves chlorophyll and other plant compounds, so the extract usually needs more refining. Cold ethanol reduces this. In a 2022 study, extraction at −40°C gave a yield of 19.7 g per 100 g of dry plant material and kept more terpenes than extraction at room temperature or at −20°C (Addo et al., 2022).
What about hydrocarbon and solventless extraction?
Hydrocarbon extraction uses butane or propane, liquefied under pressure. It keeps a lot of the aroma, but pressurising these flammable and potentially explosive gases is a safety hazard, and industrial-grade gases can leave impurities and solvent residue in the extract (Lazarjani et al., 2021).
Solventless methods separate the trichomes physically, by sieving, with ice water or with heat and pressure. They are simple but hard to scale, and the same review notes that they are less studied.
What happens after extraction?
A crude extract contains waxes, fats and plant pigments as well as cannabinoids. Typical refining steps are:
- Winterisation: the extract is dissolved, chilled and filtered so that waxes and fats separate out.
- Solvent removal: any remaining solvent is evaporated, often under reduced pressure at a low temperature.
- Decarboxylation: heat converts the acid forms in the plant, such as CBDA, into neutral cannabinoids such as CBD. Extraction at room temperature keeps the acid forms instead. Our article on how heat affects cannabinoids explains this step.
- Distillation or crystallisation: used when a more purified extract or an isolate is wanted.
- Testing: the extract and the finished product are analysed for cannabinoid content and contaminants.
How much of the plant's original profile ends up in the product depends on these steps. That is the difference between full-spectrum, broad-spectrum and isolate products, explained in Full spectrum vs broad spectrum vs isolate.
How is an extract tested?
Laboratories measure cannabinoids, usually by liquid chromatography (HPLC), and terpenes by gas chromatography. They can also test for residual solvents, pesticides and heavy metals. The results appear on a certificate of analysis. Our guides How to read a certificate of analysis and How THC levels are tested explain what to look for.
From our production
Our oils are formulated, bottled and labelled in Küssnacht am Rigi. We test every batch in Switzerland, and we have never had a failed test since 2013.
— Robin Roy Krigslund-Hansen, co-founder and CEO
Frequently asked questions
What is the hemp extraction process?
It separates cannabinoids and terpenes from the resin glands of dried hemp, usually with supercritical CO₂, ethanol or hydrocarbons. The crude extract is then refined and tested.
What is the best method for extraction of cannabinoids?
It depends on the goal. Supercritical CO₂ leaves no toxic solvent residue and can be tuned; ethanol is fast and scalable; hydrocarbons keep more aroma but bring safety and residue risks.
How does CO2 extraction work?
Under high pressure, CO₂ becomes supercritical and dissolves cannabinoids and terpenes like a liquid. When the pressure is released, it turns back into a gas and leaves the extract behind.
What is winterisation?
A refining step in which the extract is dissolved, chilled and filtered to remove waxes and fats. It makes the extract clearer and more concentrated.
Is CBD extraction different from THC extraction?
The methods are the same. What differs is the plant: hemp for CBD is bred to contain very little THC. In the UK, the leaves and flowers of hemp are controlled, and extraction of controlled cannabinoids needs a Home Office licence.
Related guides
This article describes industrial processes for information only. It is not a guide to extracting cannabinoids at home, which can be dangerous and, for controlled cannabinoids, illegal. Formula Swiss CBD oils are cosmetic products for use on the skin. See our full disclaimer.
Last reviewed:
Sources
- Lazarjani MP, Young O, Kebede L, Seyfoddin A. Processing and extraction methods of medicinal cannabis: a narrative review. J Cannabis Res 2021;3:32. doi:10.1186/s42238-021-00087-9
- Addo PW, Sagili SUKR, Bilodeau SE, et al. Cold ethanol extraction of cannabinoids and terpenes from cannabis using response surface methodology: optimization and comparative study. Molecules 2022;27(24):8780. doi:10.3390/molecules27248780
- Home Office. Low THC cannabis (industrial hemp) licensing factsheet. Updated 18 December 2025.
