Cannabis and its components
Cannabis refers to the plant Cannabis sativa. The cannabis plant originally comes from Asia. It is now grown around the world, including in Canada.
Chemical substances in cannabis
Cannabis contains hundreds of chemical substances. Over 100 of these are known as cannabinoids. Cannabinoids are made and stored in the plant’s trichomes. Trichomes are tiny, clear hairs that stick out from the flowers and leaves of the plant. Cannabinoids have effects on cell receptors in the brain and body. They can change how those cells behave and communicate with each other.
The most researched cannabinoid is delta-9-tetrahydrocannabinol (THC). THC is responsible for the way your brain and body respond to cannabis, including the high and intoxication. THC has some therapeutic effects but it also has harmful effects. Harmful effects may be greater when the strength of THC is higher.
The potency (concentration or strength) of THC in cannabis is often shown as a percentage of THC by weight (or by volume of an oil). THC potency in dried cannabis has increased from an average of 3% in the 1980s to around 15% today. Some strains can have an average as high as 30% THC.
Cannabis that contains very low amounts of THC in its flowers and leaves (less than 0.3%) is classified as hemp.
Cannabidiol (CBD) is another cannabinoid. Unlike THC, CBD does not produce a high or intoxication. There is some evidence that CBD may block or lower some of the effects of THC on the mind. This may occur when the amount of CBD in the cannabis is the same or higher than the amount of THC. CBD is also being studied for its possible therapeutic uses.
Terpenes are chemicals made and stored in the trichomes of the cannabis plant, with the cannabinoids. Terpenes give cannabis its distinctive smell.
How cannabis is used
The cannabis plant is used for its effects on the mind. It is also used for medical, social or religious purposes. Marijuana is a slang term for the dried flowers, leaves, stems and seeds of the cannabis plant.
Cannabis can be taken in different ways, by:
- Joints or spliffs (cannabis rolled in cigarette paper) which may be mixed with tobacco
- Pipes and bongs (a type of pipe)
- Blunts (partially or entirely hollowed out cigar wrappers filled with cannabis)
Drinking or eating:
- cannabis oil
- baked goods
Vaporizing and vaping (breathing in dried cannabis or liquid cannabis vapours through a vaporizer or vaping device)
Dabbing (breathing in very hot vapours from heating cannabis concentrates)
The different forms of cannabis
Most cannabis products come from or can be made using the flowers and leaves of the cannabis plant. Depending on how they are made, these products can have a range of potencies of THC (and CBD). Below is a table that lists the main forms of cannabis and typical potencies of THC.
|fresh or dried herbal material||Flowers and leaves from the cannabis plant||up to 30%|
|cannabis oil||Cannabis extract dissolved in oil. Can be used to make other forms (for example, edibles).||up to 3%|
|chemically concentrated extracts (for example, hash oil/shatter/budder/wax)||Highly concentrated cannabis extract dissolved in petroleum-based solvent (for example, butane). Shatter, budder and wax most highly concentrated.||up to 90%|
|physically concentrated extracts (for example, hash/kief)||Loose trichomes or pressed resin from the cannabis plant.||up to 60%|
|edibles||Foods and drinks containing extracts of cannabis||Depends on the amount of extract added|
|tinctures/sprays||Cannabis extract dissolved in a solvent, often alcohol. Can be used to make other products (for example, edibles).||varies|
|creams/salves/liniments||Cannabis extract preparation prepared with alcohol, oil or wax and applied to the skin.||varies|
Short-term health effects
The flowers and leaves of the cannabis plant are used for their ability to cause effects on the mind, including:
- feeling high (euphoria)
- a sense of well-being
- heightened sensory experiences:
While cannabis may make you feel relaxed and happy, your body and brain may also experience effects that are:
Some of the short-term effects on your brain can include:
- sleepiness (fatigue)
- impaired ability to:
- pay attention
- react quickly
- anxiety, fear or panic
Short term effects on your body can also include:
- if smoking, damaged blood vessels caused by the smoke
- decreased blood pressure, which can cause people to faint
- increased heart rate, which can be dangerous for people with heart conditions and can lead to an increased risk of heart attack
Cannabis use can also result in psychotic episodes characterized by:
Long-term health effects
Long-term effects develop gradually over time, with daily or near-daily (weekly) use that continues over:
The long-term effects of cannabis on your brain can include an increased risk of addiction. Long-term cannabis use can also harm your:
- intelligence (IQ)
- ability to think and make decisions
Effects appear to be worse if you:
- start using early in adolescence
- use frequently and over a long period of time
These effects can last from several days, to months or longer after you stop using cannabis. They may not be fully reversible even when cannabis use stops.
Other long-term effects of smoking cannabis are similar to the effects of smoking tobacco. These effects can include risks to lung health, such as:
- lung infections
- chronic (long-term) cough
- increased mucus buildup in the chest
Health effects during pregnancy and breastfeeding
Just like with tobacco and alcohol, a pregnant woman or new mother’s use of cannabis can affect her fetus or newborn child.
The substances in cannabis are carried through the mother’s blood to her fetus during pregnancy. They are passed into the breast milk following birth. This can lead to health problems for the child.
Cannabis use during pregnancy can lead to lower birth weight of the baby. It has also been associated with longer-term developmental effects in children and adolescents, such as:
- decreases in:
- memory function
- ability to pay attention
- reasoning and problem-solving skills
- hyperactive behaviour
- increased risk for future substance use
Potential therapeutic uses of cannabis
There is some evidence of potential therapeutic uses for cannabis or its component chemicals (cannabinoids).
Health Canada has information for health care professionals and for authorized patients on the use of cannabis and cannabinoids for medical purposes. This includes information on:
- potential therapeutic uses
- adverse effects