Updated 24 June 2015

The real dangers of smoking dagga

The possession and use of cannabis (dagga) is illegal in South Africa, but despite this the country is ranked as one of the top cannabis producers globally and it is the commonest illicit drug abused in South Africa. Its use can lead to multiple health and psychiatric complications.


“Although cannabis (dagga) is viewed as an innocent herb by many, there is increasing concern about adverse health consequences,” says Dr Lize Weich, senior psychiatrist and lecturer at Stellenbosch University.

Many users become dependent on cannabis, it is estimated that about one in nine cannabis users will become dependent, while those who start using it in their teens have a one in six chance to become dependent. It is also linked to other medical complications, including heart attacks (one study found a nearly five-fold increased risk for this in the hour after use), as well as arrhythmias (abnormal heart rhythms) and strokes.

Smoking is the most common route of delivery of cannabis, so it is not surprising that lung problems, like chest infections, chronic bronchitis and emphysema are common among cannabis users.

Cannabis smoke also contains carcinogens (cancer causing agents) similar to that found in tobacco smoke and that may predispose an individual to lung cancer.

Cannabis use impairs driving ability and users are at a higher risk of car accidents.

Its use in pregnancy has been linked with neuro-behavioural problems in children.

“Furthermore, cannabis intoxication can lead to multiple psychiatric complications, like panic, anxiety, depression or psychotic symptoms,” Weich explains. Heavy cannabis use has been linked to reduced pro-social goal-directed behaviour (when individuals select actions based on their predicted consequences), apathy and diminished drive, referred to by some as the “amotivational syndrome”.

ReadPsychosis is five times more likely for dagga smokers

Long-term cannabis use can also affect memory and the ability to process information.

The developing adolescent brain is particularly vulnerable to the adverse effects of cannabis use. “It is the most common illicit drug used by this group and has been linked with poor educational attainment, dropping out of school, later unemployment and lower life satisfaction and even with a decline in IQ,” says Weich.

Adolescent onset cannabis use has also been linked to various psychiatric problems in this age group, including an increased risk of developing schizophrenia – a brain disorder which affects the way a person behaves, thinks and sees the world.

Although the cannabis plant contains in excess of 400 compounds, the most potent agent is delta 9-tetrahydrocannabinol (THC).

THC acts by activating the endocannabinoid receptor system, a delicate system that modulates the balance in other neurotransmitter systems, thereby ensuring optimal functioning of multiple biological functions including learning, memory, stress, appetite, movement and pain perception.

There is some potential medicinal benefit

Weich emphasizes that although there are some early studies that suggest potential medicinal benefit from cannabis use, including relief of neuropathic pain, increasing appetite and treating glaucoma, there is not yet sufficient evidence to support its efficacy and rule out harms and human trials in this regard is still largely lacking.

Read: Dagga can help HIV patients with neurological pain 

She says there is concern about the popular belief that cannabis is “medicinal” and thus “harmless and safe”, especially among children and adolescents. Studies have shown that this vulnerable population’s risk of use is influenced by how safely they perceive a drug to be.

“It is clear that legalising cannabis for medicinal use is an important topic that needs careful consideration. Much more research is required to establish efficacy along with a clear public message highlighting risks, especially among the youth,” says Weich. 

SANCA Drug Awareness Week: 24 – 28 June 2015. For more information or enquiries, contact the Mental Health Information Centre of Southern Africa at

Read more:

'I used cannabis oil to cure my cancer'

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Cannabis users risk health, wellbeing and achievement


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