The cannabis oil that is typically available in dispensaries is the THC-dominant one that contains little cannabidiol (CBD). To extract CBD-rich cannabis oil, one must start with a CBD-rich plant material.
There are many ways to extract the oil from the cannabis plant, and each has its own pros and cons. Some methods are safer and more effective than others.
Cannabis oils made with neurotoxic solvents like butane and hexane may leave unsafe residues that interfere with immune function and impede healing. Supercritical CO2 extraction is non-toxic and produces high quality oil, but it requires significant expertise and access to expensive equipment.