Though there is much to be learned about the efficacy and safety of CBD, results from recent studies suggest that CBD may provide a safe, powerful natural treatment for many health issues. For those with cancer, it may even provide a natural alternative for pain and symptom relief. One study performed on mice showed that CBD-rich cannabis extracts have the potential to cause liver toxicity. However, some the mice in the study were force-fed extremely large doses of the extract . This is especially important if you take medications or supplements that come with a "grapefruit warning." Both grapefruit and CBD interfere with cytochromes P450 , a group of enzymes that are important to drug metabolism .