There are approximately 500 natural components found within the Cannabis sativa plant, of which up to 100 have been classified as ‘cannabinoids’; chemicals unique to the plant. The cannabinoids are most abundant in the un-fertilised female flower head and this is the part of the plant utilised in the development of medicinal cannabis products.

The most well-known of the cannabinoids is delta-9-tetrahydrocannobinol (THC). It was isolated in 1964 in Israel. This cannabinoid is responsible for the psychoactive effects of cannabis and is the reason cannabis is used recreationally. However, it appears that THC may also be responsible for some of the medicinal effects of cannabis such as reduction of nausea, vomiting, pain and muscle spasms as well as improvement in sleep and appetite.

A second cannabinoid, cannabidiol (CBD) is also showing promise in the medical field, but has the advantage of not being psychoactive. It appears that CBD may mitigate some of the THC effects and, while research is continuing, there is the possibility that CBD may be useful in the management of seizures, pain, and may have anxiolytic and antipsychotic effects. At this stage, it is not known if THC and CBD act individually or in conjunction with each other.

There are numerous other cannabinoids that may be of interest in the future, including cannabigerol (CBG), tetrahydrocannabivarin (THCV), cannabinol (CBN) and cannabichromene (CBC). Generally, all cannabinoids produced by the plant are in their acid form and in relatively low concentrations.

In addition to the cannabinoids, the cannabis plant also contains more than 400 other components. Of particular interest are the terpenoids or terpenes. These substances give cannabis its flavour and aroma and include terpenes such as myrcene, limonene and linalool.

Unlike the cannabinoids, terpenes are found abundantly in nature and particularly in many foods. Terpenes may also play a part in modulating the effects of THC when taken with cannabinoids, but may also have their own pharmacological effects. Many people who presently use cannabis as a medicine believe that the combined effects of the cannabinoids with the terpenes and the other components of the plant are what is required to achieve the desired ‘medical’ effect—this is commonly referred to as the ’entourage effect’.