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The CULTA Blog

What is RSO?

man using cannabis oil

Rick Simpson Oil, more commonly known as RSO, is a cannabis oil product developed by Rick Simpson, a Canadian medical cannabis activist. RSO gets a lot of attention online from people who claim it can treat cancer, including Rick Simpson himself. Regardless of the claims, at the time of this publication (August 2021), there is currently no scientific evidence linking RSO or any other form of cannabis oil to curing or treating cancer. From what is RSO to how it’s made, here’s everything you need to know about RSO. 

A (brief) history of RSO

In 2003, Rick Simpson developed basal cell carcinoma, a form of skin cancer, on his arm. He was already accustomed to using cannabis oil, so he made his own topical cannabis oil and applied it to a bandage which he then used to cover the cancerous areas. According to Simpson, the cancerous growths disappeared within days. Although his physician refused to acknowledge cannabis oil as a treatment alternative, Simpson was eager to spread the word and later named the oil RSO after himself. 

What are the potential benefits?

Before we dive into the benefits, it’s important to note that there is no scientific evidence that RSO treats cancer or any of the other medical issues listed below. According to Healthline (which pulled the list directly from Rick Simpson’s website), RSO can be used for: 

  • Multiple sclerosis
  • Arthritis
  • Asthma
  • Infections
  • Inflammations
  • High blood pressure
  • Depression
  • Insomnia 

Of course, since RSO oil is a cannabis product, it can be used to treat any of the qualifying medical conditions listed on the MMCC website, including: anorexia, seizures, and severe nausea. See the full list of qualifying conditions here. 

What the research says

As we’ve discussed before, there remains a need for more research on cannabis and its potential medical benefits. But, there are already indicators that cannabis could be a powerful tool in treating cancer and the detrimental side effects of cancer treatments. One 2014 study on mice examined the effects of CBD/THC extracts alongside radiation therapy. According to the study’s authors, the results of the study suggest that cannabis may help prepare cancer cells to better respond to radiation. Cannabis can also be used to treat the common side effects of chemotherapy, including nausea and severe or chronic pain. 

Currently, there are two prescription drugs that are based on cannabis compounds that have been approved for medical use in the United States. Dronabinol (Marinol®) is a gelatin capsule that contains THC. It’s approved by the Food and Drug Administration (FDA) to treat nausea and weight loss caused by chemotherapy. Nabilone (Cesamet®) is a synthetic cannabinoid that acts much like THC. It’s taken by mouth to treat nausea and vomiting caused by chemo, usually when other drugs haven’t worked. 

Side effects & risks

Unlike many other cannabis oils, Rick Simpson Oil is high in THC, which is the main psychoactive chemical in cannabis. As such, it can produce a range of psychological and physical side effects, such as: paranoia, anxiety, hallucinations, low blood pressure, dizziness, sleeping issues, and impaired motor control. 

However, the biggest risk with RSO is that there isn’t any evidence that it effectively treats cancer. This can be dangerous if the cancer patient stops their doctor-recommended cancer treatment in favor of this natural alternative. If the RSO doesn’t work (and the cancer patient stops their usual treatments), cancer can continue to grow and become harder to treat with conventional methods. 

If you want to explore using Rick Simpson Oil for cancer or as treatment for other medical issues, always, always, always consult with your doctor first. 

How to use RSO

Once you’ve discussed Rick Simpson Oil in-depth with your doctor(s) and you’ve been given the green light, you may have some questions about dosage and use. RSO comes in oil form and requires no heat to be applied. Common applications include: 

  • Topical- rubbed onto the surface of the skin
  • Oral- taken as a capsule; this method takes the longest, but the effects also last longer
  • Sublingual- drops under the tongue; this has the fastest absorption rate 

Simpson has dosage instructions on his website, but please remember: they have not been vetted by medical researchers or doctors.  Dosages vary from person to person and should be discussed with your medical practitioner. Since RSO is high in THC content, it’s important to be very careful when dosing it. Always do so under the supervision of your doctor. 

RSO vs CBD oil

CBD oil is derived from hemp plants that only contain CBD, meaning they won’t produce any psychoactive effects. RSO oil, on the other hand, has a very high concentration of THC (20%+). It’s important to distinguish between the two, as Rick Simpson Oil is highly potent. If you already use CBD oil and then switch to RSO, please keep in mind that the two will produce two entirely different experiences. RSO will produce psychoactive effects, so please discuss dosing and any other questions you have with a medical practitioner. 

In case you accidentally over-do it*, check out this blog.  *If it’s an emergency, please dial 9-1-1.


Although there are instructions for making RSO oil online, we strongly advise against making your own cannabis oils. For one, it is illegal in most states. Second, it is very dangerous; DIY cannabis oil operations have resulted in fires, explosions, and injuries. And finally, professional manufacturers (like CULTA) have the tools and expertise that are required to do it safely and can provide certified test results for an accurate dose every time.

To learn more about CULTA’s high-quality RSO, visit our Baltimore dispensary. 


Disclaimer:  None of the information in this blog is intended to replace medical advice; it is purely for informational purposes. Please consult with a medical professional before incorporating RSO or any other medical cannabis product into your wellness routine.