Summary of effects of marijuana on health

Heart: Marijuana use can cause an increase in the risk of a heart attack more than four-fold in the hour after use, and provokes chest pain in patients with heart disease.

Lungs: Research has shown marijuana smoke contains carcinogens which are  irritant to the lungs, resulting in greater prevalence of bronchitis, cough, and phlegm production. Marijuana smoke contains 50-70 percent more carcinogenic hydrocarbons than tobacco smoke.

Mental health: Marijuana use has been shown to be significantly linked with mental illness, especially schizophrenia and psychosis, but also depression and anxiety.

Pregnancy: Marijuana smoking during pregnancy has been shown to decrease birth weight, most likely due to the effects of carbon monoxide on the developing foetus.

Marijuana and addiction

An often heard phrase is that “marijuana is not addictive.” In fact, scientific research has found that one in 10 marijuana users will become addicted to the drug. And if one begins in adolescence, then the number rises to one in six.

Users who try to quit experience withdrawal symptoms that include irritability, anxiety, insomnia, appetite disturbance, and depression. Because of its addictive nature that is why people find themselves so hooked in and dependent on it to assume “normality”.

In the past decade, researchers from all corners of the world have documented the problem of marijuana use and driving. Linked to deficits in the parts of the brain that are important for driving, including the impairment of motor co-ordination and reaction time, this is also because marijuana contains neurotoxins that is substances that affect the nerves and damaging them in the long run, hence the shaking we see on some users when they have not taken the marijuana.

Many people incorrectly believe that marijuana isn’t addictive. While many people who use marijuana do not become addicted to this drug, recent scientific research has shown that a significant percentage of individuals who use marijuana will become physically dependent on the drug. This means that stopping their marijuana abuse will cause these people to experience a “withdrawal syndrome.”

The overwhelming consensus from mental health professionals is that marijuana is not helpful and potentially dangerous for people with mental illness.

Using marijuana can directly worsen symptoms of anxiety, depression or schizophrenia through its actions on the brain. People who smoke marijuana are also less likely to actively participate in their treatment missing more appointments and having more difficulty with medication-adherence than people who abstain from using this drug.

To the young person do not experiment on marijuana and to the adult group already using help is at hand as continual use of marijuana could in the long run lead to mental illness.

Mthandazo Ndlovu is a drug prevention and rehabilitaion specialist. For help and more information contact 00263772399734 or email

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