What is Rick Simpson Oil (RSO) and How to Use It?

Last updated on July 1, 2026 · Originally published December 13, 2017

Rick Simpson Oil (RSO) is a potent, full-spectrum cannabis extract that has become one of the most widely used and talked-about products in medical cannabis. The oil takes its name from Rick Simpson, a Canadian cannabis activist who popularised it in the early 2000s after using a homemade cannabis oil to treat skin cancer lesions — though high-THC cannabis oil extracts had existed long before Simpson brought them to mainstream attention.

What made RSO distinctive wasn’t a new extraction technology. It was Simpson’s decision to share his protocol openly, distribute the oil free of charge, and document his experience treating thousands of patients — which turned a relatively obscure preparation into a fixture of medical cannabis culture worldwide.

What Makes RSO Different From Other Cannabis Extracts?

RSO is generally considered a full-spectrum cannabis extract because it retains a broad range of cannabinoids and many of the plant’s naturally occurring compounds. That said, the exact chemical profile varies depending on the extraction method and starting material — and some volatile terpenes may be lost during the alcohol evaporation process, meaning commercial RSO products can differ significantly from one another. This distinguishes it from isolates (pure CBD or pure THC) and from distillate-based products, which are refined down to an even narrower cannabinoid profile by design.

The extraction method also sets RSO apart. Where BHO uses butane as a solvent, RSO is traditionally made using isopropyl alcohol or grain alcohol — a process that strips the plant material of its chemical compounds and leaves behind a thick, dark, highly concentrated oil. The finished product is characteristically dense and sticky, with a dark brown or black color that comes from the full range of plant compounds being retained rather than filtered out. THC content in commercial RSO typically runs between 60 and 90%, making it one of the more potent extract formats available.

How Strong Is RSO?

THC content in commercial RSO typically runs between 60 and 90%, making it one of the more potent extract formats available. Because RSO is extremely thick and sticky, it’s almost always packaged in oral syringes, which allow patients to dispense very small, accurate doses — a practical necessity given how concentrated the oil is.

How to Use Rick Simpson Oil

In the legal cannabis market, patients can generally find RSO at their local recreational or medical cannabis shop. Once they bring it home, however, many patients aren’t sure how to use it.

Simpson famously applied the oil directly to skin cancer lesions. While RSO is commonly used topically for various skin conditions, there is currently no high-quality clinical evidence demonstrating that topical RSO treats skin cancer. For those who need to take the medicine internally, they should ingest it. Dabbing RSO is not advised — the high residual plant material content and the alcohol extraction method make it unsuitable for the high-heat application that dabbing requires.

Starting dose: Because RSO is highly concentrated, starting low is important. Most clinicians and cannabis-experienced healthcare providers recommend beginning with a very small amount, once or twice a day. This allows the user to gauge the psychoactive effects before increasing the dose.

Titrating up: Any dose increases should be gradual and based on individual tolerance and response. Simpson’s original protocol called for doubling the dose every few days toward a target of 1 gram daily — an escalation pace that many patients find too aggressive, particularly those who are older, THC-naive, or sensitive to psychoactive effects. There is no clinical evidence that faster escalation produces better outcomes, and side effects from moving too quickly (disorientation, anxiety, excessive sedation) are common. A slower, more conservative approach — increasing dose weekly rather than every few days, and stopping once the desired therapeutic effect is achieved rather than chasing a fixed target — is likely safer and more tolerable for most people.

How to take it: RSO can be placed under the tongue or between the gums and the inside of the lip, where cannabinoids absorb into the bloodstream more directly than through digestion. It can also be mixed into food — though its bitter taste usually needs masking. Mixing it into something fatty (nut butter, coconut oil, avocado) can support absorption, since cannabinoids are fat-soluble.

Talk to a provider first: RSO at therapeutic doses involves significant THC quantities. THC and other cannabinoids can inhibit or compete for liver enzymes in the cytochrome P450 system, potentially altering how some medications are metabolized — including blood thinners, certain antidepressants, and some chemotherapy agents. Anyone using RSO alongside other medications, or for a serious condition, should discuss it with a healthcare provider before starting.

Storing RSO

RSO should be stored in an airtight container, away from light and heat. A cool, dark drawer or the refrigerator works well for longer-term storage. The thick, sticky consistency makes it harder to work with when cold, so allowing it to come to room temperature before dosing is practical. Stored correctly, RSO holds up well over several months without significant loss of potency.

How to Make Rick Simpson Oil at Home

Although many people make RSO at home, the process involves large volumes of highly flammable solvent and should only be performed with appropriate safety precautions and excellent ventilation — preferably outdoors and away from any open flame or spark source. It requires:

• Cannabis
• Solvent of choice (99% isopropyl alcohol or food-grade ethanol are the most common)
• 5-gallon bucket
• Deep wooden bowl
• Wood spoon
• Cheesecloth
• Rice cooker
• 60ml plastic catheter tip syringe

For the full directions, Rick Simpson’s FAQ at phoenixtears.ca covers the process in detail. One important note: the use of naphtha — a petroleum-based solvent Simpson used in his original method — is not recommended. Isopropyl alcohol or food-grade ethanol are the safer and more widely accepted alternatives for home preparation.

Does RSO Treat Cancer?

This is the question at the heart of RSO’s reputation, and it deserves a direct answer: the evidence that RSO treats cancer in humans is currently limited to anecdotal reports and case studies. The preclinical research on cannabinoids and cancer cells is genuinely promising — but promising in a petri dish or in mice is a long way from proven in humans. For a full look at what the research actually shows on RSO and cancer, including both the supporting studies and the evidence that complicates the picture, see our companion article: Does Rick Simpson Oil Actually Treat Cancer? What the Research Shows.

Originally published December 2017. Updated July 2026 to reflect current clinical guidance on dosing, medication interactions, and the evidence base for RSO.

RSO is one of several cannabis extracts covered in T&T’s extraction series. For a broader look at how RSO compares to BHO and other extraction methods, see our Cannabis Extracts Guide from BHO to RSO.