Tetrahydrocannabinol (THC) is the active chemical in cannabis and is one of the oldest hallucinogenic drugs known. There is evidence that cannabis extracts were used by the Chinese as a herbal remedy since the first century AD. Cannabis comes from the flowering tops and leaves of the hemp plant, Cannabis sativa. For centuries this plant has been widely cultivated around the world for its fibres, and indeed the word canvas, which is a material made from woven hemp fibres, takes its name from cannabis. However, cannabis is more commonly known as the source of the marijuana drug, although the word marijuana applies both to the whole plant, and to the resin from it (although this is sometimes also called hashish).

 Cannabis is a Class-B drug in the UK. It is illegal to: possess or supply cannabis-based products for medicinal use without a prescription.

Dimethyltryptamine (DMT) is a hallucinogenic tryptamine drug that naturally occurs in many plant species. It can also be made in a laboratory. DMT is sometimes referred to as Dimitri, this drug produces effects similar to those of psychedelics, like LSD and magic mushrooms. Plants that contain DMT have been used in religious ceremonies in some South American regions for centuries.

 DMT is a Class A Drug and is therefore illegal to distribute or possess. As a DMT containing plant, ayahuasca is therefore illegal in the UK.