Quick answer: Start below a grain of rice. A 1 gram RSO syringe testing at 70 percent total THC holds about 700 mg of THC, which is seventy Washington edible servings in one plastic tube. A sensible first dose is 5 to 10 mg, roughly a pinhead of oil. Then wait two full hours before touching it again.
Before any of that: if you are taking RSO for a health reason, or you take prescription medication, talk to a healthcare provider who knows your history. We are a licensed Washington retailer. We can explain how this product behaves, not what it will do for you.
What is RSO and why is it so much stronger than an edible?
RSO is a whole plant cannabis extract, dark and thick and closer to tar than to oil, sold in Washington in a 1 gram syringe with a blunt plastic tip. Rick Simpson, a Canadian, popularized the method in the early 2000s: soak plant material in a solvent, filter it, then evaporate the solvent off until only resin is left.
A gummy is mostly gelatin and sugar with a measured amount of distillate stirred in. RSO is the concentrate itself. Licensed RSO here usually tests between 50 and 90 percent total THC, and 60 to 80 percent is what we see most often on our shelves. Our piece on FECO versus RSO covers where those two terms diverge.
Does Washington's 10 mg serving limit apply to RSO?
It does not, and this catches people out constantly. Under WAC 314-55-095, a single serving of a cannabis-infused product must not exceed 10 mg of active delta-9 THC, and a package meant to be eaten or swallowed cannot exceed 100 mg. That is the rule behind every gummy tin in Washington.
RSO is not an infused product. It is a cannabis concentrate, and the Washington State Liquor and Cannabis Board caps a single unit of concentrate at one gram. No serving line, no scoring, no tray of ten squares. A legal syringe can carry six or seven hundred milligrams of THC with nothing dividing it up.
You are the portioning mechanism, which is why the arithmetic matters more here than anywhere else in the store.
How do you convert the label into milligrams per dose?
Three numbers, and only three.
The three numbers you need
- Total weight. Almost always 1 gram, meaning 1000 milligrams of oil filling close to 1 mL of the barrel.
- Total THC percentage. Washington labs report total THC as delta-9 THC plus 0.877 times THCA. Newer state rules also push producers to report it in milligrams per gram, which saves a step.
- Dose volume. The barrel is your measuring tool. Most are graduated in tenths, and a tenth is a very large dose.
A worked example
Take a syringe labeled 1 gram at 72 percent total THC. 1000 mg times 0.72 gives 720 mg of THC in the tube. Across a 1 mL barrel, that is 72 mg in every tenth.
Now scale down. A tenth is 72 mg. Half of that is 36 mg. Half again is 18 mg. Half once more, roughly 0.0125 mL, is about 9 mg, just under a standard Washington serving and a reasonable place for an adult with some edible experience to start.
Run that math before the first dose, not after.
What does one dose of RSO actually look like?
A grain of rice is not a unit of measurement, which is the quiet flaw in every RSO chart online. Published estimates for a rice-grain portion run from 0.025 mL to 0.05 mL, and rice varies by variety. Use it as a picture, then check it against the barrel. Figures below assume 70 percent total THC.
| Dose size | Rough volume | Approx. THC at 70 percent | Realistic for |
|---|---|---|---|
| Pinhead | 0.01 mL | About 7 mg | First RSO dose, or anyone with little edible experience |
| Half grain of rice | 0.015 to 0.025 mL | 10 to 17 mg | Someone comfortable with a 10 mg gummy |
| Full grain of rice | 0.025 to 0.05 mL | 17 to 35 mg | Regular edible consumers, evening use only |
| Two grains of rice | 0.05 to 0.1 mL | 35 to 70 mg | High daily tolerance, and still a heavy dose |
| Whole syringe | 1 mL | About 700 mg | No one, in one sitting, ever |
That last row is there because people ask.
How long does RSO take to work and how long does it last?
Swallowed, expect 30 to 90 minutes before you feel much, occasionally up to three hours on a full stomach, with the peak commonly two to four hours in. Effects typically run six to eight hours, and a big dose leaves a foggy edge the next morning.
Inhaled cannabis behaves nothing like that. Onset is five to ten minutes and it is usually over inside two to four hours, which is why a disposable vape is easier to steer in real time. You feel a vape working and you stop. With RSO, by the time you feel it, you took that dose an hour ago.
There is a pharmacological reason. Anything swallowed passes through the liver first, where enzymes including CYP2C9 and CYP3A4 convert much of the delta-9 THC into 11-hydroxy-THC, a metabolite that crosses into the brain readily and is generally reported as producing stronger effects than delta-9 THC itself. Inhaling skips that first pass. Same milligram count, different chemistry arriving.
The terpene content of the source material survives in a whole plant extract, and the indica or sativa label predicts far less than the milligram number.
The mistake almost everyone makes
Redosing at the 60 minute mark.
That is the most common way an RSO night goes sideways, and it is a timing problem, not a tolerance problem. Someone takes a rice grain, feels nothing at 45 minutes, decides the dose was too small, takes another, and both arrive together around hour two.
Two rules fix it. Set a timer, and put the syringe in a drawer in another room. Uncertainty is not evidence the dose failed. It usually means you are 40 minutes into a 90 minute onset. If you want to increase, increase on a different day.
How do you actually take RSO?
Squeeze the dose onto something you can swallow: a cracker, a spoonful of peanut butter, an empty capsule. A little dietary fat helps, and it gets the taste over with, because RSO tastes of scorched plant matter and it does not improve. Some people hold it under the tongue a few minutes first and report a sooner onset.
Warm the syringe in your hand before dispensing. Cold RSO is stubborn, and the moment it moves you tend to get four times the dose you meant. Cap it, store it upright somewhere cool and dark, away from anyone under 21 and from pets.
What about the 60 grams in 90 days protocol?
You will find this everywhere, so here it is stated plainly and once. Rick Simpson has said he consumed roughly 60 grams of the oil across about 90 days, and that regimen circulates online under his name. It has never been validated in controlled human research, and 60 grams of high-potency oil is an enormous quantity of THC, in the range of tens of thousands of milligrams.
We mention it as history because people ask about it by name. It is not guidance and not something we advise. Anyone weighing high-dose cannabis alongside a serious diagnosis needs a physician in that conversation, not a retail website.
What if someone has taken too much?
Overconsumption feels genuinely awful and can last hours. The WSLCB lists the signs: intense anxiety or panic, confusion, a racing heart, higher blood pressure, severe nausea and vomiting, sometimes hallucinations.
What state guidance suggests: water, a quiet familiar room, slow breathing, sleep if it comes. Tell someone what you took and when. Do not drive, and do not add alcohol.
The Washington Poison Center takes calls at 1-800-222-1222, free and confidential, 24 hours a day, 365 days a year. Use it. For chest pain, repeated vomiting, or anything that frightens you, call 911 or go to an emergency room, and tell the clinician exactly what you took.
What we tell people over the counter
The question we get at West Seattle and Redmond is almost never "what is RSO". It is someone holding a syringe asking how much to eat. Our Cannabis Guides will do the percentage math with you at the register and show you that dose against the barrel.
Two things we say most days. Buy where the total THC on the label came from a certified lab, because that number is the entire basis of your dose, and our guide to spotting fake cannabis products covers the rest. And if oral cannabis is new to you, a 10 mg gummy from the West Seattle edibles menu or the Redmond edibles menu is a more forgiving way to find your number.
Frequently asked questions
How much RSO should I take the first time?
Less than a grain of rice. A pinhead, roughly 0.01 mL from the syringe, is about 7 mg of THC in a product testing at 70 percent total THC. If you have never taken an edible, halve that again. Take it at home, in the evening, and take no second dose that night.
How many milligrams of THC is a rice grain of RSO?
A grain of rice is not a real unit, which is the problem with the convention. Estimates run from about 0.025 to 0.05 mL. In RSO at 70 percent total THC, that is roughly 17 to 35 mg, or two to four Washington edible servings in one smear.
How long does RSO take to kick in?
Swallowed, usually 30 to 90 minutes, and sometimes three hours after a large meal. Peak effect commonly lands two to four hours in. That lag is why people redose too early and end up far higher than planned. Set a timer for two hours and make no decisions before it goes off.
How long do the effects of RSO last?
Six to eight hours is normal for an oral dose, and a large one carries a foggy tail into the next morning. Inhaled cannabis is mostly done in two to four hours. Plan an RSO dose the way you would plan an evening you are not driving anywhere.
Is RSO subject to Washington's 10 mg serving limit?
No. Under WAC 314-55-095, the 10 mg per serving and 100 mg per package limits apply to cannabis-infused products meant to be eaten or swallowed. RSO is sold as a concentrate, and a single unit of concentrate cannot exceed one gram. Nothing portions it for you, so a 1 gram syringe can legally hold several hundred milligrams of THC.
What should I do if I took too much RSO?
Sit down somewhere familiar, drink water, and tell someone what you took and when. The Washington Poison Center answers at 1-800-222-1222, free and confidential, 24 hours a day. Call 911 or go to an emergency room for chest pain, repeated vomiting or symptoms that frighten you, and tell the clinician exactly what you took.
Before you open the syringe
Do the math first, and write your dose in milligrams on the box in pen, because you will not want to do arithmetic later. Start smaller than feels necessary, wait the full two hours, keep the next morning clear.
And the line worth repeating at the close as much as the open: if there is a health reason behind your interest in RSO, that conversation belongs with a healthcare provider who knows your history and your medications. Bring the syringe in, or bring the questions before you buy one.
Origins Cannabis is a licensed Washington retailer serving adults 21 and over in Redmond and West Seattle. Nothing here is medical advice. If you are using cannabis for a health reason, talk to a healthcare provider who knows your history.