A 20-year old study, investigating the effects of long-term cannabis use has revealed some shocking facts about its safety that have been, so far, overlooked. Professor Wayne Hall and his colleagues found the drug to be highly addictive, leading to a variety of mental health problems. Supporters of the drug’s legalisation will not feel very happy with this latest findings but Professor Hall warns of these key side-effects:

  • One in six teenagers who regularly smoke the drug become dependent on it,
  • Cannabis doubles the risk of developing psychotic disorders, including schizophrenia,
  • Cannabis users do worse at school. Heavy use in adolescence appears to impair intellectual development
  • One in ten adults who regularly smoke the drug become dependent on it and those who use it are more likely to go on to use harder drugs,
  • Driving after smoking cannabis doubles the risk of a car crash, a risk which increases substantially if the driver has also had a drink,
  • Smoking it while pregnant reduces the baby’s birth weight (DailyMail)

Although many people, over the years, celebrities amongst them too, have been trying to defend the drug, emphasising its medical properties, its recreational use has always been questionable. The DEA on its official website describes the drug as ‘ mind-altering (psychoactive), produced by the Cannabis sativa plant. ‘The effects of marijuana on perception and coordination are responsible for serious impairments in learning, associative processes, and psychomotor behaviour (driving abilities).


Long term, regular use can lead to physical dependence and withdrawal following discontinuation as well as psychic addiction or dependence.’

Hall, a professor of addiction policy at King’s College in London, dropped claims that cannabis is harmless. ‘If cannabis is not addictive then neither is heroin or alcohol,’ he said. ‘It is often harder to get people who are dependent on cannabis through withdrawal than for heroin – we just don’t know how to do it.’

He added that due to the fact that overdosing from cannabis is not possible, it makes it look less harmful, often leading to young users totally disregarding its effects. He writes that using the drug long-term does raise the risks of cancer, heart attack and bronchitis and that using it while pregnant can significantly reduce the baby’s weight.

Cannabis, is too often seen as a relatively ‘safe’ drug despite the fact that heavy cannabis users experience withdrawal symptoms just like heroin and alcohol addicts. The paper shows that those who try quitting cannabis use, often suffer from insomnia, depression, anxiety and appetite disturbances, amongst others. More interestingly, even after treatment, the study showed, that only less than half ex users can stay off the drug for six months.


Regular cannabis use among teenagers does lead to long-term mental health problems and awareness should be raised within parents, teachers and professionals involved with children and teenageres. More information about drug use can be found here.

Mark Winstanley, of the charity Rethink Mental Illness, said: ‘Too often cannabis is wrongly seen as a safe drug, but as this review shows, there is a clear link with psychosis and schizophrenia, especially for teenagers.

‘The common view that smoking cannabis is nothing to get worked up about needs to be challenged more effectively. Instead of classifying and re-classifying, government time and money would be much better spent on educating young people about how smoking cannabis is essentially playing a very real game of Russian roulette with your mental health.’ (DailyMail)

(Source: ScienceDaily)

Psychologist, world citizen, mother - Effie is one half of the alwaysladies.com founding pair. She can bring to life any party with either a smile, or a strong opinion. If like us you can't get enough of Effie, visit her blog at www.thethinkingmomblog.com

Leave a Reply