RSO vs. FECO: What's the Difference in These Cannabis Oils?

Two of the most-asked-about cannabis products at Missouri dispensaries are RSO and FECO. They look similar. They're both dark, thick, full-spectrum cannabis oils. But there are meaningful differences in how they're made, what they contain, and how you use them. Here's a plain-language breakdown.

What Is RSO?

RSO stands for Rick Simpson Oil. It's named after Rick Simpson, a Canadian cannabis activist who popularized the use of high-THC cannabis oil as a medicinal substance in the early 2000s. Simpson claimed to have treated his own skin cancer with a thick, full-spectrum cannabis oil made by extracting cannabis using naphtha or isopropyl alcohol.

Traditional RSO uses a solvent-based extraction process where cannabis plant material is soaked in a solvent, the solvent draws out cannabinoids and other compounds, and then the solvent is evaporated off — leaving a dark, tarry oil. The resulting product is full-spectrum: it contains THC, CBD, minor cannabinoids, and a range of plant compounds.

What Is FECO?

FECO stands for Full Extract Cannabis Oil. It's a broader category that includes oils made using a variety of extraction methods — including food-grade ethanol extraction, which is generally considered cleaner and more precise than traditional RSO solvents.

FECO made with pharmaceutical-grade ethanol produces a product that is full-spectrum but with a more consistent cannabinoid profile and fewer residual plant waxes and chlorophyll. The taste is typically cleaner, and the process allows for more accurate dosing.

Key Differences

The core difference comes down to the extraction solvent and process. Traditional RSO uses harsh solvents. Modern FECO typically uses high-grade ethanol or CO2. Both produce full-spectrum cannabis oil, but FECO tends to be more refined, more consistent, and easier to dose. The term 'RSO' has also evolved colloquially — many dispensaries now use RSO and FECO interchangeably to mean any thick, full-spectrum cannabis oil, regardless of the specific extraction method used.

How to Use Them

Both RSO and FECO are typically consumed orally or sublingually. Common methods include placing a rice-grain-sized amount under the tongue, mixing into food, or taking it in a capsule. These oils are extremely potent — significantly more so than standard flower or edibles. If you're new, start with the smallest possible dose (think the tip of a toothpick) and wait at least two hours before taking more.

Robust offers both FECO syringes and FECO capsules. The capsules take the guesswork out of dosing and are ideal for patients who want a consistent, mess-free experience.