What is Rick Simpson Oil?

TL;DR: Rick Simpson Oil (RSO) is a potent THC-dominant cannabis extract first popularized for cancer treatment. While it helped start a medical cannabis movement, it lacks the safety standards, cannabinoid diversity, and patient-specific tailoring found in today’s lab-tested FECO.

The Origin of RSO

RSO was created by Rick Simpson, a Canadian engineer who used a homemade THC-rich oil to treat his own skin cancer. He shared his recipe publicly and encouraged others to make their own oil using strong solvents like naphtha or isopropyl alcohol. His story went viral. For many, it was the first time cannabis was seen as a real medical solution.

What’s Actually in RSO?

Traditional RSO is high in THC, often exceeding 70–90%, with little to no CBD. It’s thick, black, and usually unrefined. The original method didn’t involve lab testing, terpene preservation, or solvent removal verification. As a result, potency and safety varied drastically.

“RSO saved my life—but I wish I’d had guidance. The nausea and paranoia almost made me quit.”
— Lauren K., 51, breast cancer survivor, transitioned to FECO with better results

RSO vs. FECO: A Necessary Comparison

While RSO brought cannabis into the medical spotlight, FECO (Full Extract Cannabis Oil) has emerged as the next evolution—designed for patient safety, full-spectrum healing, and personalized care.

Feature RSO FECO
Solvent used Naphtha, isopropyl Food-grade ethanol
Lab tested? No (homemade) Yes (batch verified)
CBD content Minimal Custom ratios (CBD/THC)
Patient guidance None Clinically guided protocols
Safety risk Residual solvents Lab-purged and verified

The Science of Why It Works

RSO and FECO both act on the body’s endocannabinoid system (ECS), a regulatory network that influences inflammation, immune response, pain, mood, sleep, and even cancer cell apoptosis.

In THC-rich oils, CB1 receptors in the brain and nervous system are primarily activated, promoting:

  • Pain reduction
  • Nausea control
  • Appetite stimulation
  • Neuroprotective responses

However, CB2 receptors, which reside in immune tissues, bones, and the peripheral nervous system, are equally vital. These receptors regulate immune inflammation and help mediate the anti-cancer and autoimmune-modulating effects of full-spectrum cannabis medicines like FECO.

Key studies:

Testimonials: What Patients Say

“RSO gave me hope, but FECO gave me control. I could dial in relief, not just endure it.”
— Sam D., 61, prostate cancer

“We tried RSO on our own. The side effects scared my husband. With King Harvest, we got help.”
— Rita and Paul V., 67 & 70, Parkinson’s and caregiver

“As a first-time THC user, RSO was overwhelming. FECO let me ease in and stay functional.”
— Tony R., 54, chronic pain

Patient Tracking Tools

We encourage patients to track their symptoms, dosages, and experiences to guide care and share outcomes. Download our free Patient Journal template to get started.

Safety Guidelines

  • ⚠️ Never use homemade RSO with solvents not meant for human consumption
  • ⚠️ Always ask for lab results and cannabinoid profiles
  • ⚠️ Avoid if pregnant, nursing, or taking medications metabolized by CYP450 enzymes
  • ⚠️ Do not drive or operate machinery after dosing
  • ✅ Look for full-spectrum blends and licensed producers
  • ✅ Store in a cool, dark place away from children

Frequently Asked Questions

  • Is RSO illegal? Legal status varies by state. Check Norml.org for up-to-date info.
  • Can RSO cure cancer? No. It may support symptom management and quality of life. Always work with an oncologist.
  • What’s the best starting dose? Start low: ~0.05g (size of a grain of rice). Increase slowly under guidance.
  • Can I switch from RSO to FECO? Yes—and most patients experience improved tolerance, results, and fewer side effects.

Start Your Healing Journey

Learn more about FECO or speak with our integrative care team to create a safe, effective plan. Healing doesn’t have to be guesswork.

Written by The King Harvest Integrative Health Team