Last reviewed 08/2022

Cannabis is formed from the dried flowering tops of hemp plants which have euphoric properties. It is classified as a hallucinogen.

Cannabis is very widely grown and available, and is usually smoked with or without tobacco. It is obtained as dried leaves or as a resin. It induces feelings of well-being, relaxation and tranquility, though it may also give rise to apprehension, anger and depression. It is usually used socially

  • it can induce a psychotic syndrome which resolves within 48 hours. It is unlikely that it is able to trigger a prolonged psychosis (although this subject is dealt with in detail via the linked item below)
  • street names for cannabis include marihuana, ganja, kif, bhang, dagga, hashish, pot, and grass
  • in the UK, on 29 January 2004, cannabis was downgraded from a Class B to a Class C drug
  • prevalence of use The 2001/2002 British Crime Survey published by the Home Office estimated that more than three million adults in the UK had used cannabis in the previous 12 months, and two million had used it in the past month
    • it was further estimated that about 27 per cent of people in the 16-24 age group had used cannabis in the previous year, and 17 per cent had used it in the past month
    • mean age of onset of cannabis abuse is 15 years
  • cannabis contains more than 400 chemicals, about 60 of which are cannabinoids
    • cannabinoids are are compounds with a chemical structure related to delta 9-tetrahydrocannabinol (THC), which is the main active chemical
    • in terms of potency, it is reported that cannabis has become markedly stronger over the past 20-30 years, with an increase from about 0.5 per cent of THC to 5 per cent, while specially grown varieties may contain up to 30 per cent THC
      • a 'reefer' in the early 1980s contained about 10mg of THC - this compares to a modern 'joint' which may contain about 300mg of THC