Health effects of cannabis
Learn about the health risks of using cannabis and how you can reduce the risk.
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About consuming cannabis
Cannabis is a drug that comes from the dried flowers and leaves of the cannabis plant. Cannabis is also sometimes called marijuana, weed and pot.
There are different ways to use cannabis such as:
- smoking as a cigarette (sometimes called a joint or blunt), pipe or bong
- mixing it in food or drink (cannabis edibles)
- heating it and using it as oil, wax or in a form called shatter (made from cannabis resin or hash)
Cannabis contains two substances that can affect your brain and your body:
- THC (tetrahydrocannabinol) – causes the psychological effects known as feeling high and can affect your mood and behaviour
- CBD (cannabidiol) – may affect the brain, but is not intoxicating like THC
Short-term health effects can include:
If you smoke cannabis you may experience additional long-term effects, including:
- long-term cough
- lung infection
The health harms and risk of addiction from using cannabis are especially high for youth. The most effective way for youth to protect their health is to not use cannabis.
Using cannabis before you are 25 years old can affect brain function. These effects on the brain can be permanent.
Up to one in six people who start using cannabis as a teenager will become addicted to it.
For some people, using cannabis can increase the risk of developing mental health issues. Risks to your mental health from using cannabis include:
- mild or temporary symptoms of anxiety
- paranoia and delusional beliefs
- higher risk of suicide, depression and anxiety
- potential permanent brain damage
The risk of developing psychosis or schizophrenia may increase for people who use cannabis daily or near-daily. People who use cannabis before 16 years of age have a higher chance of developing psychosis or schizophrenia.
No amount of cannabis is safe to use during pregnancy and breastfeeding.
THC, the chemical in cannabis that causes psychoactive effects, is stored in body fat such as breast milk, and can be passed down to the baby when breastfeeding.
Using cannabis during pregnancy can:
- affect the brain development of the baby
- cause the baby to have a lower birth weight
- cause learning problems in the child
- increase the child’s risk of depression
Consuming too much cannabis at one time can lead to temporary adverse effects, known as cannabis poisoning.
Cannabis poisoning is not generally known to be fatal, but it can be dangerous and sometimes requires emergency medical attention.
Symptoms of cannabis poisoning may include:
- chest pain
- rapid heartbeat
- nausea or vomiting
- a psychotic episode
- shallow breathing
- severe anxiety or a panic attack
It is easier to be poisoned when consuming cannabis (eating or drinking) compared to inhaling cannabis (smoking or vaping).
Reduce your risk
The best way to avoid the health risks of using cannabis is to not use it.
To reduce the health risks from using cannabis:
- avoid smoking cannabis
- reduce how often you use cannabis
- delay using cannabis until later in life
- avoid smoking or vaping cannabis products and consider edible cannabis (which is safer for your lungs than smoking cannabis), but be aware that edibles are not risk-free and that it can take longer to feel the effects of edible cannabis than other forms
- avoid using edible cannabis from an unauthorized retailer to ensure that products are safe to consume and free of contamination
- avoid using synthetic cannabis (for example K2 and Spice)
Don’t drive high. Drug-impaired driving is dangerous and against the law. After alcohol, cannabis is the drug most linked to car accidents.
Cannabis makes it harder to concentrate, react and tell how far away things are. This affects your ability to drive safely.