Where to find RSO oil
RSO oil is sold at licensed cannabis dispensaries in states with legal medical or adult-use cannabis. Pharmacies do not stock it. Federal law bars mailing cannabis across state lines, so an out-of-state order is not an option. To find a product near you, open a dispensary menu online, search for RSO, and check store hours. Bring a government ID.
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What RSO is
RSO stands for Rick Simpson Oil. Simpson, a Canadian, publicized the extract in 2003. It is a full-extract cannabis oil. Flower is soaked in a solvent, most often ethanol, and the solvent is then evaporated. The result is a dark, thick oil with a tar-like texture. Makers package it in oral syringes that hold 0.5 g or 1 g.
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Lab-tested RSO carries 50% to 80% THC, the compound that causes a high. Some makers sell a 1:1 version with equal parts THC and CBD.
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Where it is sold
- Adult-use dispensaries: 24 states and the District of Columbia as of 2025. Counts change after each election.
- Medical dispensaries: about 40 states. A state-issued patient card is required in some of them.
- Delivery: legal in some states, including California and Nevada. Local rules vary by city and county.
Hemp-derived THC sold online is a different product. It is not RSO.
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What to check before you buy
- Lab report. Look for potency, pesticide, and residual solvent results. Ask for the batch number.
- Date. THC degrades with time. A recent batch holds more potency than an old one.
- Price. RSO syringes run about $20 to $60 per gram in US dispensaries. Medical patients pay less in some states.
- ID rules. Adult-use sales need buyers age 21 and up. Medical sales drop to 18 in many states with a card.
Legal status
Federal law lists cannabis as a Schedule I controlled substance. State law does not override that. A dispensary receipt does not protect you in a state where cannabis is illegal, and you cannot carry RSO on a flight or across a state line. Possession limits apply. In California, adults may hold 28.5 g of flower and 8 g of concentrate.
Dosing
RSO is strong. A portion the size of a rice grain weighs about 25 mg. At 60% THC, that portion holds about 15 mg of THC. Effects start in 30 to 90 minutes and last four to six hours. Wait two hours before taking more. Simpson's published protocol calls for doses up to 1 g per day, which is far above a starting dose and causes heavy impairment.
What RSO does not do
Simpson and others claim RSO treats or cures cancer. The FDA has not approved cannabis or RSO for cancer treatment. No human clinical trial has shown that RSO cures cancer. FDA-approved cannabinoid drugs are specific products with specific uses: Epidiolex for seizures, dronabinol (Marinol, Syndros) for nausea and weight loss, and nabilone (Cesamet) for nausea from chemotherapy.
Storage and use
Keep the syringe in a cool, dark place. Warm the plastic in your hand for a minute before use so the oil moves. RSO is taken by mouth, under the tongue, or rubbed on the skin. It is not made for vaping.