What Is RSO Oil & FECO? (Rick Simpson Oil & Full Extract Cannabis Oil – UK Guide 2026)

Rick Simpson Oil (RSO) and FECO (Full Extract Cannabis Oil) are highly concentrated, full-spectrum cannabis extracts containing very high levels of THC (typically 60–90%). RSO was popularized by Canadian cannabis activist Rick Simpson, while FECO is the broader term many people in the UK use when searching for "feco oil uk" or similar potent extracts.

In 2026, searches for "what is rso oil", "what is feco", "rso oil uk", "feco uk" and "rso vs feco" continue to grow as more people explore high-potency cannabis options beyond regular CBD oil. This page provides a clear, factual educational overview of what these products are, how they differ from CBD, and the current legal situation in the United Kingdom.

Important: RSO and FECO are not approved medical treatments in the UK. They are Class B controlled substances and may only be legally accessed through a specialist medical cannabis prescription from a GMC-registered clinician.

History of Rick Simpson Oil

Rick Simpson developed RSO in 2003 after a personal health challenge. He created a concentrated cannabis oil using a simple solvent extraction method and began sharing both the oil and his protocol freely online. His story and anecdotal experiences quickly spread around the world, leading to huge interest in RSO as a potent full-spectrum extract.

In the UK, awareness of RSO increased significantly after the law changed in November 2018 to allow specialist prescriptions for cannabis-based medicinal products. However, traditional RSO-style oils remain unlicensed and are only legally available through proper medical channels.

What Is FECO? (Full Extract Cannabis Oil in the UK)

FECO stands for Full Extract Cannabis Oil. It is the general term used for any highly concentrated cannabis extract that keeps the full range of cannabinoids, terpenes, and other plant compounds. In the UK, people searching for "feco oil uk" or "full extract cannabis oil uk" are usually looking for the same type of thick, dark, high-THC oil as RSO.

RSO vs FECO vs CBD – Key Differences

RSO is actually a specific type of FECO made using Rick Simpson’s method. In everyday use, the two terms are often used interchangeably. Both RSO and FECO are very high in THC and are full-spectrum extracts.

CBD oil is completely different — it is derived from hemp, contains almost no THC, is non-psychoactive, and is legally sold over the counter in the UK. Many people who start with CBD eventually search for information about stronger full-spectrum options like RSO and FECO.

How RSO or FECO Is Made

Traditional RSO and FECO are produced by soaking dried cannabis flowers in a food-grade solvent (most commonly isopropyl alcohol), then carefully evaporating all the solvent to leave behind a thick, sticky, dark oil. This process extracts the maximum amount of cannabinoids and terpenes from the plant.

In the United Kingdom, producing high-THC extracts at home is illegal. Only licensed facilities and regulated manufacturers are allowed to produce cannabis-based medicinal products.

RSO THC Percentage & Potency

Authentic RSO and most FECO typically contain between 60% and 90% THC. This makes them some of the strongest cannabis extracts available. The high potency is why they are strictly regulated and classified as Class B controlled substances in the UK.

RSO / FECO vs CBD Oil – Quick Comparison