The Truth About Rick Simpson Oil (RSO): What Patients and Science Say About Cancer Claims
Exploring the science, stories, and controversy behind one of cannabis’s most talked-about extracts.
Could a homemade cannabis oil hold the key to easing cancer symptoms—or even slowing its growth? That’s the question many patients, caregivers, and researchers are exploring when it comes to Rick Simpson Oil (RSO).
If you missed last week’s post, we explored the science behind how cannabis may affect cancer cells in Can Cannabis Really Fight Cancer? This Massive Study Says Yes — And Here's Why That Matters.
In this post, we take a deeper look at:
What RSO is and where it came from
Real stories from patients and caregivers who have used it
What research says about its biological effects on cancer
The risks, controversies, and potential for future treatments
We won't make any promises—just present what we know, what’s been experienced, and what’s still to be learned.
What Is Rick Simpson Oil (RSO)?
Rick Simpson Oil is a highly concentrated cannabis extract, known for its very high THC content—often over 90%—along with other cannabinoids and terpenes. It typically comes in a syringe and is taken orally (in tiny doses, often called “rice grain-sized”) or applied topically.
It was developed by Rick Simpson, a Canadian engineer who claimed he used homemade cannabis oil to treat his own skin cancer in 2003. After seeing what he believed was a successful self-treatment, Simpson began sharing his oil—and his extraction method—with thousands of patients, freely and without profit. His story gained viral attention after the release of his 2008 documentary Run From the Cure, and RSO became a symbol of patient-led, cannabis-based cancer support.
Today, RSO is produced by various companies and often sold in dispensaries, though Simpson himself is no longer publicly active after a stroke in 2018.
Real People, Real Experiences: Why Patients Explore RSO
Beyond headlines and lab results, some of the most compelling insights come from patients and caregivers who’ve used RSO as part of their cancer journey.
One long-time caregiver shared this reflection:
"I’ve made a great deal of Rick Simpson Oil for many cancer patients over the years. If I were diagnosed today, I’d follow conventional medicine—but I’d also start RSO right away. One rice grain a day, building up slowly. I haven’t seen it cure anyone, but I’ve seen it help them hold on longer—with less pain and more dignity."
They noted how patients using cannabis often appeared physically better than those who didn’t:
“The difference between a leukemia patient on cannabis and one who isn’t? Night and day. One can eat, sleep, and stay upright. The other is often bruised, bedridden, and in constant pain.”
Other patient stories include:
A stage 4 neuroendocrine cancer patient who began using RSO after being given 3–5 years to live. Thirteen years later, they remain stable and continue cannabis use.
A woman with advanced breast cancer found that tiny doses of RSO under the tongue eased severe nausea during chemotherapy and brought back her appetite.
Multiple patients with glioblastoma multiforme (GBM) have reported extended survival after incorporating THC:CBD cannabis oil alongside standard treatments. In one small report, nearly half of the patients were still alive at 24 months—over double the typical survival time.
These experiences don’t suggest RSO is a cure, but they raise questions worth exploring.
How RSO Might Work: The Science Behind the Oil
While there are no large-scale human studies proving RSO cures cancer, scientists have studied how cannabinoids like THC and CBD affect cancer cells in labs and animal models. Here’s what they’ve found so far:
Triggering Cancer Cell Death
In many laboratory studies, cannabinoids have been shown to cause apoptosis—a type of programmed cell death—in cancer cells. A 2024 study in mice with pancreatic cancer found that a THC/CBD extract significantly slowed tumor growth and increased cancer cell death. The cannabis compounds seemed to “push” cancer cells to self-destruct while sparing healthy ones.
Slowing Tumor Growth and Spread
Cannabinoids may also stop cancer cells from dividing rapidly, hinder their ability to spread to other tissues, and block the growth of new blood vessels that tumors need to survive (a process called anti-angiogenesis).
Potential Synergy with Chemo and Radiation
Some early studies suggest cannabis compounds could make traditional treatments more effective. One study in brain cancer showed that combining THC and CBD with radiation dramatically shrank tumors more than radiation alone. While promising, these findings are mostly in animals or early-phase human trials.
Clinical Trials and Early Human Data
Although full-scale clinical trials are still lacking, there have been small studies and case reports:
A 2016–2021 clinical trial combined a THC/CBD oral spray with chemotherapy in glioblastoma patients. After one year, 83% of those receiving cannabinoids were still alive, compared to 44% in the placebo group.
A case report from the UK described an 81-year-old woman whose lung tumor shrank significantly over two years of daily CBD oil use. While encouraging, doctors noted there’s no way to be certain CBD was the cause.
A 14-year-old boy with terminal leukemia showed improvement in blast cell counts while receiving RSO, though he ultimately did not survive.
There is also some evidence that cannabinoids can interfere with certain immunotherapies—highlighting the importance of medical supervision.
What RSO Users Say About Side Effects
RSO is potent, and it isn’t without side effects. Users often describe a period of intense sedation, especially in the early days:
“In the first two months, I slept almost all the time. I was in a weed coma until my tolerance built up.”
Another user shared that they experienced a grand mal seizure after starting high doses of RSO. While it’s unclear if cannabis was the cause, it underscores the need for caution, especially for those with neurological conditions.
Taste and texture are also a barrier:
“It tastes terrible. But it’s easy to dose—just a small amount on a cracker or under the tongue.”
To minimize psychoactive effects, some users prefer balanced THC:CBD oils (like Harlequin RSO) or suppositories, which bypass digestion and may reduce the high.
Choosing the Right Formula: THC, CBD, and Ratios Matter
Traditional RSO is high in THC, but some patients—and caregivers—are experimenting with more balanced formulas.
“A 1:1 THC to CBD ratio made the experience more tolerable. Especially if used at night, after dinner, when feeling loopy isn’t disruptive.”
The late Corrie Yelland, a passionate patient advocate who helped thousands explore cannabis oils for cancer, shared her insights widely before her passing. She was known for working with individuals facing glioblastoma and other advanced cancers, often sharing real-world outcomes through her public channels.
Based on her experience, Corrie often recommended:
Multi-strain Full Extract Cannabis Oil (FECO)
A ratio of at least 4:1 THC to CBD
Suppositories or nasal sprays to increase brain delivery with fewer side effects
Dietary changes like low sugar, low carb, or anti-inflammatory diets
Final Thoughts: Is RSO a Cure? No. Is It Worth Exploring? Possibly.
So far, there’s no clinical proof that RSO or cannabis oils can cure cancer. But there is mounting anecdotal evidence—and emerging scientific interest—that suggest it may ease symptoms, support standard treatments, and improve quality of life for some patients.
The most responsible approach is to stay curious, informed, and collaborative with your healthcare team.
If You’re Considering RSO, Here Are a Few Tips:
Talk to your oncologist before starting any cannabis therapy
Start with microdoses—especially with THC-rich oils
Consider balanced blends for gentler effects
Time your doses wisely (evening use may minimize disruption)
Join a support group to learn from others' experiences
Disclaimer: The information provided on this blog is for educational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider before starting or changing any treatments, including cannabis use.