Many different cannabis strains are collectively called medical cannabis. Since many varieties of the cannabis plant and plant derivatives all share the same name, the term medical cannabis is ambiguous and can be misunderstood. A Cannabis plant includes more than 400 different chemicals, of which about 70 are cannabinoids.[12] In comparison, typical government-approved medications contain only one or two chemicals.[12] The number of active chemicals in cannabis is one reason why treatment with cannabis is difficult to classify and study.[12]