Rick Simpson Oil (RSO) is a thick, dark cannabis extract that carries high levels of THC. It takes its name from Rick Simpson, a Canadian man who began promoting the oil in the early 2000s for skin cancer and other health problems. RSO is not CBD oil: it delivers a strong psychoactive high, and under US federal law it remains a Schedule I cannabis product that only some state programs allow.
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What Is Rick Simpson Oil?
RSO is a full-extract cannabis oil. Makers soak cannabis flower in a solvent, strip the solvent away, and keep the sticky resin left behind, which holds THC, other cannabinoids, terpenes, and plant waxes.
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Simpson started sharing his method in the early 2000s after he said the oil cleared his own skin lesions. His account spread through documentaries and forums, and "RSO" became the common name for any full-extract oil of that type.
The oil has no fixed formula. THC content, texture, and color shift with the starting plant material and the extraction method, so two batches from two makers can differ a lot.
How Is Rick Simpson Oil Made?
Solvent extraction
The classic method uses isopropyl alcohol or high-proof ethanol. Plant material sits in the solvent for a short wash, then the liquid passes through cloth or a coffee filter.
Alcohol is flammable and the process gives off fumes, so commercial producers use closed-loop equipment and lab hoods. Home extraction near an open flame has caused fires and explosions.
Decarboxylation and finishing
Raw cannabis holds most of its THC as THC acid, which does not get you high. The extract is heated to convert THCA into THC, a step called decarboxylation.
The same heat cooks off the solvent. What remains is a dark, tar-like oil or a waxy solid, packed into glass syringes for dosing.
What Cannabinoids Are in RSO?
THC is the main active compound, and in most RSO samples it makes up the bulk of the cannabinoid content. The exact percentage depends on the strain and the process, so labels vary from batch to batch.
- THC: the primary psychoactive compound, present at high levels.
- CBD: found in small amounts unless a high-CBD strain was used.
- Other cannabinoids: CBG, CBC, CBN, and THCV appear in trace to moderate amounts.
- Terpenes: aromatic compounds that survive a low-heat process.
- Plant matter: waxes, chlorophyll, and lipids give RSO its bitter taste and dark color.
RSO vs. CBD Oil: What Is the Difference?
People confuse the two because both come in syringes or dropper bottles. They are not interchangeable.
- Main compound: RSO is THC-dominant. Most retail CBD oil is CBD-dominant with little or no THC.
- Effect: RSO causes intoxication. CBD oil does not.
- Source: RSO comes from cannabis. CBD oil sold online in the US comes from hemp in most cases.
- Law: hemp CBD with 0.3% THC or less is legal under federal law. RSO is not, outside state cannabis programs.
- Taste: RSO is bitter and herbal. CBD tinctures taste mild, often with added flavor.
How Do People Use RSO?
Simpson's protocol starts with a dose about the size of half a grain of rice, taken two to three times a day, with the amount raised over weeks as tolerance builds. He suggested swallowing it or holding it under the tongue.
Others rub it on the skin, stir it into food, or vape it in a cartridge. Each route changes how fast the effect arrives and how long it lasts.
A slow start matters. A large first dose can bring hours of anxiety, racing heart, and disorientation. Anyone on prescription drugs should clear RSO with a doctor first, since THC can interact with blood thinners, sedatives, and other medicines.
What Does the Research Say?
Clinical evidence for RSO is thin. No controlled human trial has shown that the oil cures cancer, and much of what circulates online comes from case reports and lab-dish studies.
That does not mean THC has no medical use. The FDA has approved THC-based drugs such as dronabinol and nabilone for chemotherapy-related nausea and vomiting, and for appetite loss in some patients.
Researchers keep studying cannabinoids for pain, muscle spasticity, and sleep. Results vary by condition, dose, and delivery method, and researchers call for larger trials.
Is RSO Legal in the US?
Under federal law, cannabis and cannabis extracts with THC sit in Schedule I. That covers RSO in every state.
State law runs on a separate track. Most states have a medical cannabis program of some kind, and many allow adult-use sales. Patients in those states buy RSO at licensed dispensaries with a card or a doctor's recommendation.
Crossing state lines with RSO is a federal offense, and mailing it is illegal. A hemp-derived product with 0.3% THC or less follows other rules, but it is not RSO.
Safety, Side Effects, and Risks
- Intoxication: high doses impair coordination, memory, and judgment. Do not drive after taking it.
- Anxiety and paranoia: common with THC, most often in people who take too much.
- Physical effects: dry mouth, red eyes, fast heartbeat, and lower blood pressure.
- Dependency: heavy daily THC use can lead to cannabis use disorder in a small share of users.
- Interactions: THC can change how the body breaks down some drugs, including warfarin and sedatives.
- Not for everyone: people who are pregnant, under 21, or have a history of psychosis should avoid it.
How to Judge Quality and Store RSO
Ask for a certificate of analysis. A lab report should show cannabinoid potency plus tests for pesticides, heavy metals, mold, and residual solvent.
Residual solvent matters most, since the extraction uses alcohol or another chemical. A clean report lists the solvent below the state limit or states "not detected."
Store the oil in a cool, dark place in a sealed glass container. Heat and light break down THC over time, and oxygen turns the oil darker and more bitter.
Frequently Asked Questions
Does RSO cure cancer?
There is no proof that it does. Anecdotal reports and lab studies exist, but no controlled trial in humans has shown that RSO cures cancer. Cancer patients who want to try it should talk with their oncology team first.
Can I buy Rick Simpson Oil online?
Not as a THC product shipped across state lines. It is sold in licensed dispensaries in states with legal cannabis. Online "RSO" labeled as hemp is a CBD extract with a similar look, not the same product.
How is RSO different from THC distillate?
Distillate is purified THC with most other compounds removed. RSO is a full extract that keeps waxes, chlorophyll, and terpenes, so it hits in a different way and tastes stronger.
How much THC is in Rick Simpson Oil?
There is no set standard. Most dispensary RSO is THC-dominant, with far more THC than CBD, but the exact figure changes with the strain and the extraction. Check the lab label for the batch you buy.