Rick Simpson Oil (RSO) for Cancer: Does It Work?

Medically Reviewed by Jennifer Robinson, MD on May 16, 2022
3 min read

Rick Simpson Oil (RSO), an oil made from the flowers of the cannabis (marijuana) plant, gets attention online from people who claim it treats cancer. There's no solid evidence for it. But some early research suggests that some chemicals in marijuana have future potential as a cancer treatment.

Cannabis oil comes in many types and formulations. These include cannabidiol (CBD) oil, which is often part of medical marijuana.

Unlike many other cannabis oils, Rick Simpson Oil is high in tetrahydrocannabinol (THC), which is the main psychoactive chemical in marijuana. THC is the chemical in marijuana that provides the "high."

Online reports say Simpson is a Canadian engineer and cannabis activist. After a bad fall, he found that marijuana helped lessen his dizziness and other symptoms. Later, when he developed basal cell skin cancers on his arm, Simpson used cannabis oil as a treatment. As the reports go, his skin cancers went away.

RSO is an oil made by washing cannabis buds with a solvent, such as pure light naphtha, and then boiling off the solvent leaving behind the oil.

RSO is not a branded product. That means there's no one "Rick Simpson Oil" for sale. On his website, Simpson explains how to make his namesake oil. But he does not sell a version of the oil for profit.

Because RSO contains high levels of THC, it's illegal to buy in many places. But in states that have legalized marijuana -- either for personal use or for medical use -- you can find RSO at cannabis dispensaries.

Cannabis oils that contain THC may help control nausea and vomiting for people who are going through chemotherapy. There's also evidence that they can treat pain and improve appetite.

But research has not shown that RSO or other forms of cannabis oil can treat cancer. Some very early studies on using THC to treat cancer have been encouraging, though.

In animals and in the lab, studies have found that THC and other cannabis chemicals can stop the growth of tumors. These lab studies have looked at cells related to lung, skin, breast, prostate, and other cancers. They've found that cannabis can in some cases stop the cancer cells from spreading.

Other research on THC and other cannabis compounds shows that they may kill off cancer cells while sparing healthy cells.

Cannabis is generally safe. Common side effects include dizziness or memory problems.

Many U.S. states and the District of Columbia have legalized marijuana for medical use. There's evidence that it can treat pain, nausea, and other symptoms.

When it comes to cannabis oil, there are also medical benefits. Research has shown that some CBD oils, including those that contain THC, can help control certain types of seizures among people with epilepsy. The FDA has approved some drugs that contain CBD for seizure treatment.