Cannabis contains around 100 cannabinoids. According to current knowledge, these are only present in hemp. The two most studied cannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD).
The narcotic effect of hemp is attributable to THC, which is why cannabis has been subject to the Narcotics Law. THC is found in maximum concentration in the unfertilised female flowers (up to 30%) and in the leaves close to the flowers. Among the supposed therapeutic effects of THC, the reduction of pain and, in old age, the stimulation of the appetite are those of most interest to people suffering from rheumatism.