Cannabis 101

What is Rick Simpson Oil? Your complete guide to RSO

Published on June 9, 2022 · Last updated September 30, 2022

Rick Simpson Oil, called RSO for short, is one of the most versatile and lauded cannabis innovations—an oil created by Rick Simpson, a Canadian engineer and cannabis advocate who was radicalized to cannabis activism by a work accident that led to various health issues. 

The story goes that he was able to resolve his health issues with RSO, a dark, tar-like cannabis extract that straddles the line of concentrate, edible, and topical. In short: There’s very little it can’t do, and a lot it can do for both patients and stoners. Here’s everything you need to know about RSO.

What is RSO?

Put simply, RSO is an oil derived from cannabis. But rather than a solvent extract that strips trichomes from buds, RSO contains all the cannabinoids, terpenes, and additional compounds of the whole cannabis plant. 

The extraction process is complex and fairly long, similar to making a tincture. It’s typically near-black in color, and, admittedly, doesn’t taste great due to its high amount of plant matter (it uses the whole plant).  

RSO was created as a medicinal therapeutic for cancer and other chronic health conditions, like MS and asthma. While Rick Simpson no longer produces the oil himself, it remains a crucial ingredient in the treatment plans of patients across North America.

Who Is Rick Simpson and What Is Rick Simpson Oil (RSO)?
Rick Simpson. (Courtesy of Rick Simpson)

Rick Simpson’s story

Rick Simpson wasn’t looking to become a marijuana icon. He was a Canadian engineer working at a hospital in 1997, tasked to work on some asbestos-covered pipes in a boiler room. The poor ventilation and toxic fumes caused him to pass out and fall off his ladder, after which he was taken to the emergency room. 

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He developed tinnitus and dizzy spells soon after, and no prescribed medication seemed to help. Despite its illegality and against the advice of his doctor, Simpson began using medical marijuana with great results in reliving his symptoms. 

In 2003, he was diagnosed with basal cell carcinoma, a type of skin cancer. By then, Canada had legalized cannabis for medicinal purposes, but it was hard for Simpson to find a doctor who supported his use. A 1975 study in the The Journal of the National Cancer Institute showed how cannabis and its compounds inhibited tumor growth in mice, inspiring him to create RSO. 

He has always maintained that applying RSO to his cancer growth and leaving it bandaged for four days cured him of cancer, but this has not been independently verified. 

Simpson began producing the oil en masse and distributing it to thousands of patients for free. In 2009, his property was raided by the Royal Canadian Mounted Police and thousands of cannabis plants were confiscated. 

To escape legal persecution, Simpson now lives in Croatia and maintains a website for his RSO recipe, dosing guide, and books. In 2018, he suffered a stroke and has since receded from the public but continues to advocate for RSO and medical cannabis.

A patient’s guide to using cannabis for cancer

Benefits of RSO

Despite Rick Simpson’s near-miraculous recovery from cancer and tinnitus, cannabis’ Schedule I status means the scientific community lacks consistent research to back up these claims. As more and more states legalize adult-use cannabis, however, more data becomes available. 

There have been promising reports that attest to RSO’s efficacy, such as a 2013 article showing that the use of RSO severely decreased the leukemic blast cell count in a 14-year-old terminal patient, with no toxic side effects.  

Anecdotally, RSO has helped patients manage conditions such as multiple sclerosis, epilepsy, cancer, insomnia, chronic pain, and asthma, among many others. 

As an incredibly potent THC product, RSO offers potential therapeutic effects, such as pain relief and appetite stimulation, and it can aid with sleep aid and nausea. But because studies haven’t been done, we can’t guarantee that RSO will impart these benefits. 

A 2021 study indicated that while many cancer patients use cannabis in conjunction with cancer treatments, their primary care teams lacked insight on how to integrate cannabis into a regimen. Clearly, much more research needs to be done on how best to use RSO to amplify treatment.          

Rick Simpson Oil for cancer treatment

Rick Simpson was motivated to create RSO by his own cancer diagnosis. His recipe is based on creating a product that produced the same results as a 1975 study, which showed cannabis killing cancer cells in mice. 

Simpson has said he cured his skin cancer by using RSO topically, but that it can be taken orally to address internal cancers as well. This claim has not been independently verified, but in the years since RSO was invented, thousands of patients have used it to address symptoms and improve their quality of life. 

Cancer patients seeking to use RSO should always first consult their primary care doctor to discuss their options.   

RSO for back pain

One of the most common uses for RSO, and cannabis in general, is chronic pain. Back pain is one of the most common forms of physical pain, with as much as 80% of people experiencing it at some point in life. 

RSO recipes typically call for high-THC and indica-dominant cannabis (although CBD-rich options do exist), and the final product is highly intoxicating, hence the gradual dosage increase to prevent too strong of a high. THC binds with CB1 receptors in the endocannabinoid system, most of which are concentrated in the brain and nerve cells. When THC binds to these nerve receptors, the sensation of pain lessens.

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Is RSO dangerous?

Despite its high concentration of THC, no amount of RSO will cause an overdose, death, or lasting side effects. Risks associated with taking RSO are the same as taking a high dose of any cannabis product, such as an edible, concentrate, or more of any product than one is comfortable with—namely, getting too high, and having to wait for the effects to wear off. 

RSO purchased from a dispensary has been lab-tested for solvents, pesticides, mold, and fungi, so you can rest easy that you’re getting a clean product. 

If you choose to make RSO at home, there are somewhat dangerous steps in its preparations, such as burning off an ethanol solvent, which is flammable. Some other solvents used can be explosive or produce fumes. It’s also possible that not all the alcohol will be separated from the oil before ingestion. 

If you are ever unsure about the quality of your homemade RSO, source it from a licensed dispensary.

Where can I get Rick Simpson Oil?

Since Rick Simpson Oil contains THC, you can only find it at licensed dispensaries in states with adult-use cannabis or medical marijuana. However, not all dispensaries carry RSO, as it is not as popular, nor affordable, as other forms of cannabis.   

How much does RSO cost?

Relative to a pack of gummies or an eighth of flower, RSO is expensive. Prices vary state to state and county to county based on local tax laws, but the general range for RSO is $35–70 a gram. This may seem comparable to other cannabis concentrates, but patients need 60 grams to follow the recommended RSO regimen—that’s at least $2,100!  

How to use RSO

The two most common ways to consume RSO are orally and topically. Rick Simpson himself used it as a topical to cure his skin cancer, although it’s been said his physician did not condone and cannot confirm this as a cure. 

How long does RSO take to work?

RSO requires weeks to acclimate to without intoxication. Results may be felt within a few days, but most report significant differences in symptoms once they have reached the one-gram-per-day threshold, which may take up to five weeks, depending on the individual.  

How to make cannabis edibles with concentrates

For skin ailments

If using topically, apply a dab of RSO to the skin site and cover with a band aid or bandage to ensure absorption. Reapply every other day.

For internal conditions

The other popular way to address internal conditions, such as physical pains, immunity conditions, and other illnesses, is to ingest RSO. This requires a large amount of RSO as well as a dosing system that requires weeks to acclimate to the high doses needed for treatment (more below). We recommend speaking to a doctor or medical professional familiar with RSO to discuss what works best for you. 

Our guide here is based on consuming 60 grams of RSO in 90 days, broken up into weeks, as Rick Simpson recommends on his website. Keep in mind that this hasn’t been reviewed by medical professionals.  

Side effects of RSO

Following a gradually increasing regimen of RSO is your best bet for avoiding potential side effects, such as sedation or dizziness. RSO is an incredibly potent product, and some consumers may feel uncomfortable if the dose is too high. 

It’s possible to negate the intoxicating effects of THC by adding CBD-rich flower to the recommended dosing guide below. Many patients attest that the effects of RSO are largely positive, mitigating pain, nausea, and sleeplessness, among other symptoms.   

Can you smoke or dab RSO?

Since RSO is an oil that retains some degree of plant matter, yes it can be smoked! But squirting a dollop directly in your bong or pipe will only lead to a sticky, sappy mess. 

The best way to smoke RSO is to combine it with flower, such as adding a rice grain amount to a packed bowl. It also works well in joints and blunts when added to the paper or wrap in horizontal lines. This distribution will help slow the burning of a joint or blunt and allow the RSO to heat without destroying the cannabinoids. 

Where do dabs come from? A history of cannabis extracts

And technically, yes, you can dab RSO. But we recommend only dabbing an RSO purchased from a dispensary with lab test results to ensure no solvents or other potential irritants are present. Note that when RSO is made, the cannabis is decarboxylated when the solvent is burned off, so it may not be as potent as other concentrates, depending on the temperature of your dabs.   

Can you cook with RSO?

Yes, you can cook with RSO. Keep in mind that cooking cannabis above 300ºF will burn off the cannabinoids and render the RSO useless. For maximum efficacy, it’s best to add RSO to meals that have already been cooked, or to parts of a meal that don’t need to be cooked, such as a sauce, dressing, or beverage.

RSO dosage chart

Week # in regimenIdeal dosage
1Half a grain of rice (1/4 a syringe drop) every eight hours
2Half a grain of rice (1/4 a syringe drop) every eight hours
3Half a grain of rice (1/4 a syringe drop) every eight hours
4Start doubling your dose to a full grain of rice (1/2 a syringe drop) every eight hours
5Two full grains of rice (1 syringe drop) every eight hours
6Four full grain of rice (2 syringe drops) every eight hours
7-12By now you will be ingesting approximately a gram of RSO every day, spread across three doses, taken every eight hours. Follow syringe measurements for accurate doing.
Continued maintenanceOnce the 90-day treatment plan is over, patients only need a gram or two a month to maintain a base level of cannabinoids. One gram is approximately eight syringe drops; we recommend taking this as a small dose daily or near-daily for efficacy.

RSO regimen

While Simpson recommends taking the oil orally, patients can also administer it in suppository form, using the same dosing guide.

Weeks 1-3: Three small doses every day

Start with a small dose of RSO every eight hours (morning, midday, and night). Each dose should be about the size of half a grain of rice; the first dose will be about ¼ drop of RSO from an oil syringe.

Weeks 4-5: Double your dose every four days

Per Simpson’s recommendation, it takes most patients four to five weeks to reach the full dosage of one gram of RSO per day, starting from half a grain of rice. Patients should still take their doses every eight hours.

Weeks 6-12: A gram a day

Take one gram of RSO a day until you’ve consumed a full 60 grams. This comes out to taking about 8-9 rice-sized drops of RSO every eight hours.

Continued regimen

Once a patient has gotten used to taking a gram of RSO a day and consumed the recommended 60 grams, they don’t need to continue with such high (and expensive) doses. Simpson’s website recommends one to two grams a month to maintain an influx of cannabinoids.

How to make RSO

how to make RSO, DIY rick simpson oil

This recipe follows Simpson’s own formulation to produce 60 grams of oil. This should be done in an open, well-ventilated area, as the solvent is highly combustible. Avoid all open flames such as stovetops, sparks, lighters, and cigarettes.


  • 1 pound (~450 grams) of dried cannabis (preferably indica strains)
  • 8-9 liters of a solvent (Simpson recommends 99% isopropyl alcohol)


  • Two five-gallon buckets 
  • Electric rice cooker (do not use a slow cooker or Crockpot)
  • Large wooden spoon or stirring utensil 
  • Funnel
  • Plastic syringes
  • Coffee filters or a cheesecloth
  • Large fan (for ventilation)
  • Stainless steel measuring cup (optional)
  • Coffee warmer (optional)


Step 1

Place all dry cannabis material into one of the 5-gallon buckets. Pour in the solvent until the plant matter is completely submerged.

Stir and muddle the plant material with your wooden spoon while slowly adding the solvent.

Step 2

Once fully incorporated, stir the mixture for about three minutes to allow the THC to dissolve into the solvent. This ideally will infuse about 80% of the THC into the solvent.

Step 3

Strain the plant material from the solvent into the second bucket through the coffee filters or cheesecloth. 

Step 4

With the solvent aside, put the plant material back in the first bucket and add more solvent. Continue stirring for another three minutes.

Step 5

Drain the solvent from the plant material into your second bucket again using the cheesecloth and discard the remaining plant material.

Step 6

Pour the solvent, which should now look dark, into the rice cooker until it is about ¾ full. Turn on your rice cooker.

The rice cooker should maintain a steady temperature between 210-230°F (100-110°C), in order to decarboxylate the cannabis and cook off the solvent. 

Step 7

The solvent will slowly evaporate with the heat of the rice cooker. Add your mixture to the rice cooker gradually.

Step 8

Once the solvent has evaporated, use the funnels to pack the oil into your syringe for easy dosing. The RSO will be thick like honey, so if you have trouble dispensing it, run the syringe under hot water to ease it.

Have you ever used RSO? How has it impacted your life? Let us know in the comments!

This article was originally published May 12, 2017 and is often updated for accuracy and clarity.

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Amelia Williams
Amelia Williams
New York-based freelance cannabis journalist Amelia Williams is a graduate of San Francisco State University's journalism program, and a former budtender. Williams has contributed to the San Francisco Chronicle's GreenState, MG Magazine, Culture Magazine, and Cannabis Now, Kirkus Reviews, and The Bold Italic.
View Amelia Williams's articles
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