What is RSO?

August 2022 by Sandy Yanez

RSO is a highly concentrated crude cannabis extract created by Canadian engineer Rick Simpson for the purpose of treating his skin cancer.

Rick’s cannabis journey started in 1997 when he sustained a work-related head injury from inhaling toxic fumes due to poorly ventilated conditions. Although Rick recovered, he suffered from lingering effects like ringing in the ears and dizzy spells for years after the accident. The story goes that Rick was unable to resolve his health issues with the prescribed medications given, so he turned to medical cannabis and found great results.

In 2003, three suspicious bumps appeared on his arm that were diagnosed by an oncologist as basal cell carcinoma, a form of skin cancer that develops on areas of skin exposed to the sun. Rick had watched multiple cannabis documentaries before using cannabis to treat the nagging symptoms left over from his head injury, and later a study from 1975 in the Journal of the National Cancer Institution on how THC and CBN were found to inhibit the growth of cancer cells in the lungs of mice, which lead him to the creation of RSO. Here’s what the study concluded: Delta9-THC demonstrated a dose-dependent action of inhibiting tumor growth, Delta8-THC and CBN reduced tumor size, and Delta9-THC, Delta8-THC, and CBN increased mean survival time in mice.

Rick decided he was going to treat his skin cancer with an extremely concentrated topical cannabis oil. He applied the oil directly to the painful growths and bandaged them for several days. When he removed the bandage the growths were gone. The doctors and other medical professionals refused to acknowledge that cannabis cured his skin cancer, even though the tests came back negative for cancer.

It was at this point Rick started cultivating cannabis to create RSO for other cancer patients to use for free legally in Canada. He wanted to make sure that others weren’t rejected access to this remarkable treatment due to a lack of understanding by some individuals in the medical community.

What is FECO?

Since the creation of RSO, another concentrated cannabis became available called FECO (fully extracted cannabis oil). Traditionally FECO is produced at low temperatures and is often extracted utilizing ethanol or CO2 as a solvent. This lower temperature helps keep the good stuff from burning off. Whereas RSO is typically produced at high temperatures and traditionally utilizes either alcohol or naphtha as a solvent. Higher temperatures are used with RSO production to burn off the solvent and unfortunately many of the plants’ terpenes as well.

Depending on your individual needs, one product may work better for you than the other.

Please note RSO and FECO are not the same as a dabble syringe. RSO and FECO are designed for cooking, oral, and topical application only. Dabbing or smoking is not recommended and may cause you harm.

What does the research say?

According to anecdotal claims, the concentrated forms of cannabis may help with multiple sclerosis, epilepsy, other cancers, and a variety of other conditions. Due to a lack of research on RSO, experts are cautious in supporting the benefits.

However, research does show a case from 2013 involving a young teenage girl with a specific type of leukemia. The family of the young girl worked with Rick to create a cannabinoid resin extract, referred to as hemp oil, which she took daily. The hemp oil appeared to be treating her cancer, however, she passed away from an unrelated gastrointestinal condition before completion of the cannabis.

In 2014 The American Association for Cancer Research showed that THC and CBD were beneficial when used in conjunction with radiation treatments. It showed these compounds may be useful in actually enhancing the effectiveness of the radiation treatment. Additional studies have shown that these compounds may also slow or even stop the progression of cancer cells.

A 2016 study noted that an increasing amount of preclinical test tube studies and animal models support a possible direct anticancer effect of cannabinoids and noted that anecdotal evidence suggests a high-potency oral concentrate is particularly effective.

A 2020 review stated that several studies have demonstrated the anticancer potential of cannabinoids, including D9-THC, against multiple forms of cancer. The mechanism of action included inhibition of cell growth and the progression of the cell cycle, induction of apoptosis (programmed cell death), modification of signaling molecules, inhibition of angiogenesis (formation of new blood vessels), and reduction of metastasis (development of secondary malignant growths).

While these results are promising, a great deal of clinical research is still needed before RSO can be called a potential treatment of cancer itself.


Are there risks or side effects?

RSO is an extremely concentrated form of cannabis, and the most common side effect is extreme sedation. THC, however, is a psychoactive substance, meaning it can produce a range of psychological symptoms, such as paranoia, anxiety, hallucinations, depression, and irritability. There are also physical side effects like low blood pressure, slowed digestion, sleeping issues, impaired motor and reaction time, and impaired memory. Fortunately, the physical side effects are generally short-lived and usually do not pose any major health risks.

One thing to keep in mind, some chemotherapies are immune suppressing and cannabis can make things worse by inhibiting the chemotherapy. Be sure to consult with your doctor and a cannabis specialist before you take any form of cannabis for cancer help.

Plant Family Therapeutics has an onsite medical cannabis consultant who can help assist you with your cannabis concerns and dosing.


Abrams D. I. (2016). Integrating cannabis into clinical cancer care. Current oncology (Toronto, Ont.), 23(2), S8–S14. https://doi.org/10.3747/co.23.3099

Braun, I. M., Nayak, M. M., Revette, A., Wright, A. A., Chai, P. R., Yusufov, M., Pirl, W. F., & Tulsky, J. A. (2020). Cancer patients’ experiences with medicinal cannabis-related care. Cancer, 127(1), 67–73. https://doi.org/10.1002/cncr.33202

Lal, S., Shekher, A., Puneet, Narula, A. S., Abrahamse, H., & Gupta, S. C. (2021). Cannabis and its constituents for cancer: History, biogenesis, chemistry and pharmacological activities. Pharmacological Research, 163, 105302. https://doi.org/10.1016/j.phrs.2020.105302

Rick Simpson’s website http://ricksimpsonofficial.com/message-from-rick/

Scott, K., Dalgleish, A., and Liu, W. (2014). The combination of cannabidiol and Δ9-tetrahydrocannabinol enhances the anticancer effects of radiation in an orthotopic murine glioma model. Mol Cancer Ther. 13(12), 2955-2967. https://doi.org/10.1158/1535-7163.MCT-14-0402

Singh, Y., & Bali, C. (2013). Cannabis extract treatment for terminal acute lymphoblastic leukemia with a Philadelphia chromosome mutation. Case reports in oncology, 6(3), 585–592. https://doi.org/10.1159/000356446