What Is RSO Oil? (Rick Simpson Oil Explained – UK Guide 2026)
Educational content only • Updated February 10, 2026
Fresh February 2026 batch shown – dated for clarity and peace of mind.
Rick Simpson Oil (**RSO**) is a highly concentrated, full-spectrum cannabis extract containing very high levels of THC (typically 60–90%). It was popularized by Canadian cannabis activist Rick Simpson, who shared his personal experiences online.
Important: RSO is not an approved medical treatment in the UK. It is a Class B controlled substance and may only be legally accessed through a specialist medical cannabis prescription from a GMC-registered clinician.
Many people in the UK search for "what is RSO oil" when exploring natural wellness options or alternatives to CBD. Unlike widely available CBD oil (non-psychoactive, hemp-derived), RSO contains significant THC, making it strictly regulated under the Misuse of Drugs Act. Always consult a qualified healthcare professional before considering any high-THC product.
History of Rick Simpson Oil
Rick Simpson developed RSO in 2003 after a personal health challenge. He created a concentrated cannabis oil using a solvent extraction method and shared his protocol online for free. The oil gained attention through anecdotal stories. In the UK, interest grew after medical cannabis was legalized for specialist use in November 2018 — however, RSO itself remains an unlicensed product outside regulated prescriptions.
How RSO Is Made
Traditional RSO is produced by soaking cannabis flowers in a solvent (typically food-grade isopropyl alcohol), then evaporating the solvent completely to leave a thick, dark, tar-like oil. In the UK, home production of high-THC extracts is illegal. Only licensed medical cannabis products from regulated manufacturers are permitted.
What Makes RSO Different from Other Cannabis Oils?
- Extremely high THC concentration (often 60–90%)
- Full-spectrum extract containing all major cannabinoids and terpenes
- Dark, thick, tar-like consistency (usually dispensed in syringes)
- Primarily used orally (rice-grain dosing) or topically — never smoked or vaped
What Does RSO Oil Look Like & Feel Like?
RSO is a thick, dark, tar-like oil (almost black or deep brown) with a strong, pungent cannabis smell. It has a sticky, resinous texture and is usually packaged in syringes for precise dosing (rice-grain sized amounts).
RSO THC Percentage & Potency
Authentic RSO typically contains 60–90% THC, making it one of the most potent cannabis extracts available. This high concentration is what sets it apart from most other oils, but it also means it is strictly controlled in the UK and only legally available via prescription.
RSO vs CBD Oil – Quick Comparison
| Feature | RSO | CBD Oil |
|---|---|---|
| THC Content | Very High (60–90%) | Negligible (<0.2% in legal products) |
| Psychoactive? | Yes | No |
| UK Legal Status | Prescription only (Class B) | Over-the-counter (legal hemp-derived) |
| Common Use | Anecdotal wellness exploration | Relaxation, anxiety, sleep |
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Important Medical & Legal Disclaimer
This page is for educational purposes only and does not constitute medical advice, diagnosis, or treatment recommendation. Rick Simpson Oil (RSO) is a high-THC cannabis extract and is not approved by the MHRA, NICE, or NHS as a treatment for any condition. Possession, production, or use without a valid prescription from a GMC-registered specialist is illegal in the UK and may result in prosecution. Always consult a qualified healthcare professional and refer to official sources (NHS, MHRA, GMC) before considering any cannabis-based product. This website does not sell, prescribe, supply, or facilitate access to RSO.