RSO (Rick Simpson Oil)

Key Takeaways

• RSO (Rick Simpson Oil) is a highly concentrated, full-spectrum cannabis extract typically containing 60-90% THC.

• RSO is not a proven cure for cancer or any other disease - there is insufficient evidence to support these claims.

• Manufacturing or possessing RSO is illegal in the UK.

• Patients interested in high-THC cannabis oil can access pharmaceutical-grade, lab-tested alternatives legally through a Releaf prescription.

Rick Simpson Oil (RSO) is a highly concentrated, full-spectrum cannabis extract that contains around 60-90% THC. 

It was named after Rick Simpson, a Canadian man who publicly promoted homemade cannabis oil in the early 2000s as a treatment for his skin cancer, though it is not a proven cure for any disease.

At a glance: Rick Simpson Oil 

What is Rick Simpson Oil (RSO)?

Rick Simpson oil is a highly concentrated cannabis oil that contains around 60-90% THC, it is a homemade product and is therefore illegal to possess or produce in the UK.

Where Rick Simpson Oil comes from

Rick Simpson is a Canadian man with no medical training. He has said he first began to make cannabis oil at home after a head injury at work left him constantly dizzy and conventional treatments were not helping.

Rick Simpson also said he used the cannabis oil to rub into skin cancer he had on his arm, and that it ‘disappeared’ within a week, but no medical records verifying this have been published. 

A documentary titled Run From The Cure featuring Rick Simpson went viral on YouTube, where he claimed cannabis was a cure for cancer, he also said he had started giving out the homemade oil in 2003, which was dubbed Rick Simpson Oil, to family and friends and it had ‘cured’ them too.

Rick also left written instructions for people to make their own oil at home using a solvent-based extraction process and the oil gained a significant following within the cannabis advocacy community.

Making and possessing cannabis products was illegal in Canada at the time, his house was raided, he stopped distributing the oil in 2009, Rick left to live in Europe in 2013.

Does Rick Simpson Oil cure cancer?

RSO is not a proven cure for cancer or any other disease.

While there is some preclinical research suggesting certain cannabinoids may have anti-tumour properties in laboratory and animal settings, it does not demonstrate that cannabinoids can shrink tumours in humans. According to Cancer Research UK, “we do not know if cannabinoids can treat cancer in people.” 

Patients diagnosed with cancer should always follow the treatment plan recommended by their oncology team. 

Medical cannabis may be prescribed alongside conventional treatment to help manage symptoms such as chronic pain, nausea, and appetite loss.

A US palliative-care study involving 184 patients with advanced-stage cancer found that of those who used medical cannabis, around 45% used fewer opioids.

One 2023 review found that cannabinoids improved control of chemotherapy-induced nausea and vomiting when used alongside standard antiemetics. 

Another study tested on animals showed that THC appears to stimulate the sense of smell by binding to receptors in the olfactory bulb in the brain, which processes scent information and makes aromas from food more potent, causing us to eat more, which can help with appetite loss.

What are the safety concerns of Rick Simpson Oil (RSO)?

RSO is a concentrated oil that has much stronger levels of THC than medical cannabis flower. The high concentration makes dosing difficult to judge and raises the likelihood of negative side effects such as anxiety, paranoia, disorientation, and vomiting.

Frequent use of high-THC products can build tolerance quickly, meaning larger amounts are needed to achieve the same effects. Cannabis use disorder is also a clinical condition and the risk of developing it is higher with frequent use of high-potency products. Withdrawals may cause irritable mood, sleep disturbance and reduced appetite.

As RSO is not available through prescription, it is illegal and either made at home or bought through the black market, which can come with serious risks. There is no way to know the potency of the cannabis, if it is contaminated with residual solvents after decarboxylation, or pesticides, and there is no medical supervision involved.

As RSO is made with a solvent, homemade RSO has a high risk of causing a fire or explosion, and producing RSO is a criminal offence under the Misuse of Drugs Act 1971, carrying a maximum sentence of 14 years.

Is Rick Simpson Oil (RSO) legal in the UK?

RSO is classified as a Class B controlled drug under the Misuse of Drugs Act 1971, and there is no legal route to possess it in the UK.  

It is not manufactured as a cannabis-based product for medical use (CBPM) so it cannot be prescribed despite it being legal to prescribe medical cannabis in the UK since November 2018.

Medical cannabis can be prescribed by a specialist doctor, where at least two conventional treatments have not provided adequate relief. 

Patients may be able to get access to prescribed high-THC medical cannabis oils similar to RSO, but not RSO itself.

Patients may be offered:

• Flower, which is prescribed for vaporisation as smoking medical cannabis is illegal.

• Oils which are taken orally.

• Vape cartridges offer concentrate-level potency in a controlled format.

• Pastilles for oral pre-measured doses.

Rick Simpson Oil (RSO) vs Medical Cannabis Oil

How prescribed medical cannabis is taken

Unlike RSO, prescribed medical cannabis is regulated and tested to ensure high-quality products and is always overseen by a specialist doctor.

RSO is usually taken as a small blob on a syringe which is hard to measure the amount of cannabinoids, it is also turned into edibles which causes another problem. The THC is often unevenly mixed and effects take much longer to appear when cannabis is eaten, so some people may take more before the first dose has taken effect.

Most patients prescribed cannabis oil take it sublingually, which means under the tongue. The dose is measured with a dropper to ensure you get the right dose each time.

You also have a specialist doctor overseeing your treatment so they can adjust your dose if needed and watch out for side-effects and check for interactions with other medicines. 

Frequently asked questions about Rick Simpson Oil (RSO)

Is RSO oil illegal in the UK?

Yes, Rick Simpson Oil is illegal in the UK under the Misuse of Drugs Act 1971. However, patients can access legal, pharmaceutical-grade high-THC cannabis oil through a specialist prescription. 

Is RSO oil the same as CBD oil?

RSO is not the same as CBD oil, CBD oil has little or no THC while RSO has a high level of THC.

Will RSO get you ‘high’?

RSO contains around 60-90% THC which is the compound in cannabis that can produce a euphoric feeling. The strength varies between batches as it is a street drug with no regulation and too much THC can cause panic attacks, paranoia and hallucinations 

How strong is RSO compared with other cannabis oils?

RSO is a high-strength THC cannabis oil. Prescribed medical cannabis can come in a range of strengths; the key difference is the known levels, as prescribed oil is lab-tested while RSO’s strength is unknown.

Can you smoke RSO?

RSO is a concentrated oil that is not designed for smoking. Prescribed medical cannabis oil is usually administered sublingually. 

Does RSO help with pain or sleep?

There is no clinical evidence to suggest that RSO helps with pain or sleep because it has never been tested in clinical trials. Regulated prescribed medical cannabis may offer relief for chronic pain and sleeping disorders.

How much RSO should you take?

There is no safe or recommended dose of RSO because its strength is unknown, and it’s  illegal in the UK. Prescribed medical products will be assessed by a specialist who will set your dose.

To find out if you are eligible, try our free medical cannabis eligibility checker, it takes less than 30 seconds to fill in.

Our medical cannabis glossary can also help you learn more about terms you may associate with medical cannabis. 

Releaf - redefining healthcare