RSO stands for Rick Simpson Oil, a whole-plant cannabis extract named after the Canadian who popularized the method in the early 2000s. In a Washington dispensary, RSO is one of the most concentrated things on the shelf, usually sold in a 1-gram syringe or in capsules.
What's actually in it
RSO is made by soaking cannabis flower or trim in a food-grade solvent (usually grain alcohol), then evaporating the solvent off. What's left is a thick, dark, tar-like oil that carries the full spectrum of cannabinoids and terpenes from the original plant, not just isolated THC.
Two things follow from that:
- It's potent. A typical RSO syringe runs 60 to 90% total THC. For comparison, dispensary flower is 18 to 28%, and vape cartridges run 60 to 90%. A rice-grain amount, about a quarter of a 0.1 mL line, holds roughly 25 mg of THC. That's two and a half full edible servings.
- It's whole-plant. Distillate vape carts are usually isolated THC re-suspended; RSO keeps the original cannabinoid and terpene profile. Some customers prefer it for the entourage effect, the idea that cannabinoids and terpenes work together, though the research on that is still developing.
How people commonly use it
RSO comes with a graduated syringe so you can dose by volume. A tenth of a milliliter (0.1 mL) is the smallest reliable measurement.
The common methods:
- Sublingual: dose under the tongue, hold 30 to 60 seconds, then swallow. Onset is faster than a swallowed edible (15 to 45 minutes) because some absorbs through the mucosa directly.
- Capsules: pre-measured RSO in a soft gel. Onset is the same as any swallowed edible (60 to 90 minutes). Easier math.
- Topical: spread on skin. Doesn't get you high; most of the cannabinoids stay in the local tissue.
Customers asking about RSO usually fall into two groups: experienced consumers after the strongest format the legal market sells, and people exploring whole-plant cannabis after talking to their doctor. We're not in that second conversation. We sell what's on the shelf, we describe what's on the label, and we don't make medical claims. If RSO is part of a treatment conversation, that's one to have with your doctor.
Reading the RSO label
Every RSO product in Washington has a Certificate of Analysis from a licensed lab. The numbers worth checking:
- Total THC %: typically 60 to 90%. Higher isn't always better. The terpene profile and the source strain shape the experience.
- Total CBD %: RSO comes THC-dominant, CBD-dominant, and 1:1. CBD-dominant or 1:1 RSO behaves differently than THC-dominant.
- Strain or blend: most RSO is a blend of trim from several harvests. Some producers extract from a single strain, which is rarer and often pricier.
- Producer name: the licensed Washington company that made it. We can tell you which producers we've stocked the longest if that helps.
What we will and won't say
We'll happily walk you through dosing math, label reading, and how RSO stacks up against other concentrates. We'll point you to the producers we trust.
We won't tell you RSO will treat any condition. We can't. WAC 314-55-155 prohibits cannabis retailers from making efficacy claims, and even without that rule, RSO is not a substitute for medical advice. If you're considering it as part of treating a condition, talk to your doctor first.
Common questions
Is RSO the same as FECO or QWET? Not exactly. FECO (Full Extract Cannabis Oil) and QWET (Quick Wash Ethanol) are similar whole-plant methods. The output is broadly the same; the wash time, strain selection, and post-processing vary. Most customers use the terms interchangeably.
Can I cook with RSO? Yes. It's already decarboxylated (heat-activated) during extraction, so it works in recipes without baking. Mix it into honey, oil, or a fatty food. The rice-grain dose still applies.
How long does a syringe last? A 1-gram syringe holds 1,000 mg of dose. At a beginner dose of 10 mg per use, that's 100 doses. Most customers spend one over weeks or months, not days.
Is RSO regulated like flower or edibles? Yes. It's a Washington recreational cannabis product, sold only in licensed dispensaries to adults 21 and over. Same possession limits, same testing requirements, same purchase caps.
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This is general cannabis education for adults 21 and over. We're not making medical claims about RSO. If you're considering it as part of treating a medical condition, that's a conversation for your doctor.
