Cannabis has been used as a medicine in various parts of the world for hundreds, possibly thousands of years and there are many conditions that it is thought to benefit. We know that people have continued to use, and report benefit from medical cannabis even when it has not been available for legal prescription.
However, like any medicine there is also the possibility of harmful effects. There is generally less evidence for cannabis in the form of high-quality scientific studies compared to conventional licensed treatments. This means we cannot always know whether the benefits of cannabis treatment will outweigh the possible risks. That is why it is usually recommended that cannabis should only be considered if conventional treatments have not been effective, and treatment should be under medical advice and supervision.
Cannabis does seem to show potential for being a helpful treatment for many people who have not felt sufficient benefit from conventional medications or treatments. While some people may find little or only modest benefit, others have described their response to treatment as life changing. Your doctor can help you decide whether to trial medical cannabis in your own particular circumstances.