How CBD Oil Is Made: Extraction, Refining and Testing
How CBD oil is made, from decarboxylation and CO2, ethanol or hydrocarbon extraction to winterization, carrier oils and lab testing.
- Evidence
- Moderate
- Sources
- 9 linked
- Sponsored
- No ✓
- Checked
- Nov 2026
Hemp is heated to convert CBDA to CBD, extracted with CO2, ethanol or hydrocarbons, refined to remove waxes (and THC if needed), mixed into a carrier oil, then lab tested.
CBD oil is made by extracting cannabinoids from hemp with a solvent such as carbon dioxide (CO2), ethanol or a hydrocarbon, cleaning up that extract, and then mixing it into a carrier oil like MCT or sesame oil. Along the way, the plant is heated to convert its raw acid form (CBDA) into CBD, waxes are removed, and, for isolate or broad-spectrum products, THC is separated out. Finished products should then be lab tested, because labels are often inaccurate.
- Hemp mostly contains cannabinoids in an “acid” form; heat (decarboxylation) turns CBDA into CBD.
- Commercial extraction mainly uses supercritical CO2, ethanol, or hydrocarbons like butane and propane.
- Extra steps such as winterization, distillation, chromatography and crystallization refine the extract into full spectrum, broad spectrum or isolate.
- CBD dissolves in fat, not water, which is why it is sold in carrier oils.
- Never try butane or other hydrocarbon extraction at home. It has caused explosions and serious burns.
What is CBD oil, exactly?
CBD (cannabidiol) is a cannabinoid, one of the natural compounds made by the cannabis plant. If you are new to it, see what is CBD? A bottle of “CBD oil” is usually two things: a concentrated hemp extract that contains the CBD, and a carrier oil that dilutes it into measurable drops.
It is not the same as hemp seed oil, which comes from hemp seeds and is used as a food ingredient. Read more in hemp oil vs CBD oil.
Why does hemp need to be heated first?
In the living plant, most cannabinoids exist as acids, such as CBDA and THCA. A 2025 paper in ACS Agricultural Science & Technology explains that heat removes part of the molecule (a carboxyl group), converting these acids into the neutral forms, CBD and THC. This process is called decarboxylation.
In that study, milled hemp was heated at a relatively low temperature for a long time, because the authors note that gentler conditions favor CBD while higher temperatures favor other compounds such as THC and CBN. A 2022 industry review in Frontiers in Natural Products adds that conditions must be chosen to minimize breakdown of the cannabinoids. Decarboxylation can happen before or after extraction.
How are cannabinoids extracted from hemp?
Extraction uses a solvent to dissolve the cannabinoids out of the plant material. The 2022 Frontiers in Natural Products review compared the main industrial methods:
| Method | How it works | Pros | Cons |
|---|---|---|---|
| Supercritical CO2 | Pressurized CO2 acts like a liquid solvent, typically around 100–300 bar and 35–60°C | Leaves no residue; seen as the least toxic option without co-solvents | Demanding equipment, longer extraction times, yields no better than organic solvents |
| Ethanol | Food-grade alcohol soaks the plant and dissolves cannabinoids | Generally recognized as safe (GRAS); no high pressure needed | Also pulls out chlorophyll and other compounds, requiring more cleanup |
| Hydrocarbons (butane, propane) | Liquefied gases dissolve cannabinoids in closed, pressurized systems | Does not dissolve chlorophyll; solvent is easy to purge | Highly flammable with explosion risk; toxic if inhaled; needs special facilities |
The review notes that cold ethanol reduces chlorophyll but uses more energy, while room-temperature ethanol yields about 15% more extract and needs more filtering. It also found that butane gives yields similar to ethanol, but its toxicity and flammability make it less desirable.
CO2 is not perfectly selective. In the 2025 scale-up study, CO2 extraction raised CBD from 4.5% of the plant material to 30.8% of the extract, but it also concentrated THC, to 1.5% of the extract.
What happens after extraction?
A raw extract contains cannabinoids mixed with waxes, fats and plant pigments. Manufacturers refine it in stages:
- Winterization. The extract is dissolved in a solvent such as ethanol and chilled so waxes and fats solidify and can be filtered out. In the 2025 study, mixtures were cooled to −18°C for 48 hours.
- Solvent removal. The solvent is evaporated off and ideally recovered for reuse.
- Distillation. Thin-film, wiped-film or short-path equipment further purifies the extract. The Frontiers review notes one process needed wiped-film distillation to reach 95% CBD oil.
- THC removal (broad spectrum). Further separation, such as chromatography, aims to reduce THC to non-detectable levels while keeping other cannabinoids.
- Crystallization (isolate). A highly concentrated extract is cooled so pure CBD forms crystals. In the 2025 study this only worked once the oil was more than 80% CBD, and it was the step that left THC behind.
The 2025 study produced CBD crystals above 99% purity with THC below 0.2%. Learn more about that end product in what is CBD isolate?
Full spectrum, broad spectrum or isolate: how processing decides
How far a manufacturer refines the extract determines what kind of product it becomes. A 2024 study in Frontiers in Pharmacology used these working definitions:
- Full spectrum: hemp extract with no compounds removed or added, so it contains CBD, some THC and other cannabinoids.
- Broad spectrum: extract with THC removed to non-detectable levels.
- Isolate: more than 95% CBD.
Processing does not always deliver what the label says. In that study of 202 products, 26% did not meet the definition of the type claimed, and three broad-spectrum products still contained THC.
Why is CBD mixed with a carrier oil?
CBD is highly fat-soluble and does not dissolve well in water. A 2020 review in Pharmaceuticals notes that CBD is most commonly supplied as an oil or alcohol-based formulation for this reason. The prescription CBD drug Epidiolex, for example, lists sesame seed oil and dehydrated alcohol among its inactive ingredients.
The same review reported that CBD in MCT (medium-chain triglyceride) oil showed no lipid oxidation products, suggesting MCT is less prone to going rancid than olive or hemp seed oil. Fat also matters for absorption: the Epidiolex label reports that a high-fat meal raised CBD exposure about fourfold compared with fasting. For practical use, see how to use a CBD tincture.
How is CBD oil tested?
Good manufacturers send each batch to an independent lab, which issues a certificate of analysis (COA). Testing matters because products often miss their labels. A 2017 JAMA study found only about 31% of 84 online CBD products were accurately labeled, and THC turned up in 18 of them.
Extraction can also leave contaminants behind. In the 2024 study of 202 products, residual solvents were detected in 181 products, and vape products had significantly higher hexane than other formats. Lead was found in 42 products, and pesticides in 30. A useful COA covers cannabinoid content (CBD and THC), residual solvents, heavy metals and pesticides, for the exact batch you bought.
Tip: Match the batch number on the bottle to the COA, and check that the measured CBD is within about 10% of the label. Then use our CBD dosage calculator to work out milligrams per dropper.
Why is homemade “CBD oil” different?
Some home recipes involve soaking hemp flower in a cooking oil. That is an infusion, not a refined extract, and it differs in important ways:
- Unknown strength. Without lab testing, there is no way to know how much CBD or THC is in each spoonful.
- Acid forms. Without proper decarboxylation, much of the CBD may remain as CBDA, and too much heat can push conversion toward other compounds.
- No cleanup. Home infusions keep plant material that commercial processes remove, and any THC in the flower stays in the oil.
Important: Never attempt butane, propane or other hydrocarbon extraction at home. These solvents are highly flammable and vapor can collect in enclosed rooms and ignite. A study of a Colorado burn center found 29 patients admitted for butane hash oil burns from 2008 to 2014; 93% were flash burns from explosions in enclosed spaces, and 21% needed a breathing tube to protect their airway. Commercial extraction uses closed, pressurized equipment and safety facilities for a reason.
Frequently asked questions
Is CO2-extracted CBD better than ethanol-extracted CBD?
Not automatically. CO2 leaves no solvent residue, but the 2022 Frontiers review found it does not give higher yields than organic solvents. Quality depends on the whole process and testing, so check the COA.
Does “solventless” mean no solvents were used?
Not always. CO2 extracts may still go through winterization, which uses a solvent. Residual solvent testing on the COA tells you what remains.
Can extraction create THC?
Decarboxylation converts THCA to THC as well as CBDA to CBD, and CO2 extraction can concentrate THC. That is why THC removal steps and testing matter.
Is CBD oil FDA-approved?
No. Epidiolex is the only FDA-approved CBD product, and it is a prescription medicine. Over-the-counter CBD oils are not FDA-approved, and the FDA warns about risks such as liver injury and drug interactions.
Is hemp seed oil made the same way?
No. Hemp seed oil comes from the seeds, not from cannabinoid-rich plant material. The FDA has recognized hemp seed oil as safe for food, but it is a different product from CBD extract.
Sources
- Frontiers in Natural Products — López-Olmos et al., Comprehensive Comparison of Industrial Cannabinoid Extraction Techniques (2022)
- ACS Agricultural Science & Technology (via PMC) — Calmanti et al., From Hemp to CBD Crystals (2025)
- Pharmaceuticals (via PMC) — Millar et al., Towards Better Delivery of Cannabidiol (2020)
- DailyMed (NLM) — Epidiolex (cannabidiol) prescribing information
- Frontiers in Pharmacology (via PMC) — Gidal et al., Product Labeling Accuracy and Contamination Analysis of Commercially Available CBD Products (2024)
- JAMA (via PMC) — Bonn-Miller et al., Labeling Accuracy of Cannabidiol Extracts Sold Online (2017)
- Journal of Medical Toxicology (via PMC) — Bell et al., Butane Hash Oil Burns Associated with Marijuana Liberalization in Colorado (2015)
- FDA — FDA Regulation of Cannabis and Cannabis-Derived Products, Including CBD
- FDA — What You Need to Know About Products Containing Cannabis or Cannabis-Derived Compounds, Including CBD
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