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 products on the shelf, usually sold in a 1-gram syringe or in capsule form.
What's actually in it
RSO is made by soaking cannabis flower or trim in a food-grade solvent (typically grain alcohol), then evaporating the solvent off. What's left is a thick, dark, tar-like oil that contains 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 is 60-90% total THC. For comparison, dispensary flower is 18-28% THC; vape cartridges run 60-90%. A "rice grain" amount of RSO — about a quarter of a 0.1 mL line — contains roughly 25 mg of THC. That's two and a half full edible servings.
- It's whole-plant. Distillate vape cartridges are usually THC isolated and re-suspended; RSO keeps the original cannabinoid and terpene profile. Some customers specifically prefer RSO for the "entourage effect" — the idea that cannabinoids and terpenes work together — though research on the entourage effect is still developing.
How people commonly use it
RSO is dispensed with a graduated syringe so you can dose by volume. A tenth of a milliliter (0.1 mL) is the smallest reliable measurement.
The most common methods:
- Sublingual — dose under the tongue, hold for 30-60 seconds, then swallow. Onset is faster than a swallowed edible (15-45 minutes) because some absorbs through the mucosa directly.
- Capsules — pre-measured RSO inside a soft gel. Onset is the same as any swallowed edible (60-90 minutes). Easier dosing math.
- Topical — spread on skin. Doesn't cause a high; most of the cannabinoids stay in the local tissue.
Customers who ask about RSO at the counter usually fall into two groups: experienced consumers looking for the strongest delivery format the legal market sells, and people exploring whole-plant cannabis after talking to their doctor. We're not in the 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, it's a conversation for your doctor.
Reading the RSO label
Every RSO product in Washington has a Certificate of Analysis from a licensed lab. The numbers to look at:
- Total THC % — typically 60-90%. Higher isn't always "better" — the terpene profile and the strain it was extracted from matter for the experience.
- Total CBD % — RSO comes in THC-dominant, CBD-dominant, and 1:1 versions. CBD-dominant or 1:1 RSO has different effects than THC-dominant.
- Strain or "blend" — most RSO is a blend of trim from multiple harvests; some producers extract from a single strain (single-strain RSO is rarer, often more expensive).
- Producer name — the licensed Washington company that made it. We can tell you which producers we've stocked the longest if that's useful.
What we will and won't say
We'll happily walk you through dosing math, label reading, and how RSO compares to other concentrates. We'll point you toward the producers we trust.
We won't tell you RSO will treat any specific condition. We can't — Washington's WAC 314-55-155 prohibits cannabis retailers from making efficacy claims, and even if it didn't, RSO is not a substitute for medical advice. If you're considering RSO as part of treating a condition, talk to your doctor first.
This information is general cannabis education for adults 21 and over. We're not making medical claims about RSO. If you're considering RSO as part of treating a medical condition, that's a conversation for your doctor.
