Marijuana, hashish and hashish oil all derive from the cannabis plant. Cannabis sativa, also known as the hemp plant, has been cultivated for centuries for industrial and medical use, and for its "psychoactive," or mind-altering, effects.

More than 61 chemicals, called cannabinoids, have been identified as specific to the cannabis plant. THC (delta-9-tetrahydrocannabinol) is the main psychoactive cannabinoid, and is most responsible for the "high" associated with marijuana use.

Hemp grown for industrial use has very low levels of THC. Hemp fibres are used to make rope, fabric and paper.

Hemp seeds are high in protein and yield an oil with nutritional and industrial value.

Many claims about the medical uses of marijuana have not been scientifically proven; however, some have. In Canada, THC and other pure cannabinoids are available in three prescription medications:

• Marinol (dronabinol) is synthetic THC and Cesamet (nabilone) is another synthetic cannabinoid. Both are prescribed to relieve nausea and vomiting and to stimulate appetite. This can help people who have AIDS or who take drugs used to treat cancer.
• ​Sativex, the world's first prescription medicine derived from the cannabis plant, was approved in Canada in 2005 for the relief of pain in multiple sclerosis. Sativex is a combination of THC and cannabidiol.

Street names:
Marijuana - Grass, weed, pot, dope, ganja and others
Hashish - Hash
Hash oil - Weed oil, honey oil

Where does Cannabis come from?

Cannabis is native to tropical and temperate climates, but is cultivated around the world. Modern illegal growing operations use sophisticated methods to produce high-potency marijuana.

People with a medical exemption from Health Canada may grow their own supply or designate someone to grow it for them. Research-grade cannabis is grown by a producer appointed by the federal government.

What does cannabis (marijuana) look like and how is it used?

Marijuana is the dried flower buds and leaves of the cannabis plant. It ranges in colour from grayish green to greenish brown and may contain seeds and stems.

Hashish is the dried, compressed resin of cannabis flower tops. It ranges in colour from brown to black, and is sold in chunks.

Hash oil is made by boiling cannabis flower tops or resin in an organic solvent, which produces a sticky reddish-brown or green substance.

The THC content of each variety of cannabis varies, although hash is generally more potent than marijuana, and hash oil is usually the most potent form.

Marijuana, hash or hash oil are sometimes mixed with tobacco, and are most often rolled into a cigarette called a joint, or smoked in a pipe. Cannabis is sometimes cooked in foods, such as brownies, or made into a drink.

Who uses cannabis?

Cannabis is the most commonly used illegal drug in Canada (after alcohol use by minors). However, most cannabis use is infrequent and experimental.

A 2009 study reported that 42 per cent of Ontarians over the age of 18 had used cannabis at some point in their life, and 12 per cent had done so in the past year.

Another survey from 2009 found that about 26 per cent of Ontario students in grades 7 to 12 had used marijuana at least once in the previous year. About three per cent reported daily use in the past four weeks. These rates of use were significantly higher among males than females.

Cannabis (marijuana) and the law

A first-time conviction for possession of 30 grams or less of marijuana can result in a six-month jail sentence or a $1,000 fine (or both) – and a criminal record, which limits employment and travel. Subsequent convictions and possession of larger amounts can result in more severe penalties. A first offence of possession of small amounts of cannabis usually results in a fine or discharge.

In 2007, 47,000 people were arrested for possession of marijuana; this was about half of all drug arrests in Canada for that year. In an ongoing debate lasting many years, various government, health, police, policy and legal groups have suggested that criminal punishment for the possession of cannabis is too severe.

One alternative to current laws is to "decriminalize," which would reduce the legal penalty for possession of cannabis, and another is to "regulate," giving cannabis a legal status similar to alcohol.

New regulations were enacted under Canada's Controlled Drugs and Substances Act to permit the cultivation of industrial hemp in 1998, and to provide access to marijuana for medical use in 2001.​

Adapted from Do You Know . . . Cannabis © 2003, 2010 Centre for Addiction and Mental Health

Effects​

How cannabis affects you depends on:

• how much you use
• how often and how long you've used it
• whether you smoke it or swallow it
• your mood, your expectations and the environment you're in
• your age
• whether you have certain pre-existing medical or psychiatric conditions
• whether you've taken any alcohol or other drugs (illegal, prescription, over-the-counter or herbal).

When people first try cannabis, they often feel no psychoactive effect. With repeated use, however, these effects are felt.

People can have very different experiences with marijuana and other forms of cannabis. Some may feel relaxed, lively, talkative and giggly, while others feel tense, anxious, fearful and confused. What's more, the kind of experience a person has can vary from one drug-taking episode to another. People who are familiar with the drug learn to stop when they've had enough, and have more control of the effects than do people who are new to the drug.

At low doses, cannabis mildly distorts perception and the senses. People who use the drug say that it makes music sound better, colours appear brighter and moments seem longer. They say that it enhances taste, touch and smell and makes them feel more aware of their body. Some enjoy these effects, but others find them uncomfortable.

Smoking larger amounts may intensify some of the desired effects but is also more likely to produce an unpleasant reaction. Too high a dose may result in feelings of losing control, confusion, agitation, paranoia and panic.

Pseudohallucinations (seeing things such as pattern and colour that you know are not real) or true hallucinations (where you lose touch with reality) can occur.

The physical effects of cannabis include:

• red eyes
• dry mouth and throat
• irritated respiratory system (from smoking)
• bronchodilation (expansion of breathing passages)
• increased appetite and heart rate
• decreased blood pressure, balance and stability
• possible drowsiness or restlessness, depending on the amount taken and individual response to the drug.
  

How long do the effects last?

When cannabis is smoked, the effect is almost immediate and may last several hours, depending on how much is taken. When it is swallowed, the effect is felt in about an hour, and lasts longer than when it is smoked.

Although the high lasts only a few hours after smoking, THC is stored in fat cells and expelled from the body over a period of days or weeks, depending on the frequency of use and the amount used. This is why drug tests for cannabis use can give a positive result long after the effect of the drug has worn off.

Is cannabis (marijuana) dangerous?

While no one has ever died of a marijuana overdose, those who use cannabis should be aware of the following possible dangers, and take measures to avoid them:

• Cannabis impairs depth perception, attention span and concentration, slows reaction time, and decreases muscle strength and hand steadiness – all of which may affect a person's ability to drive safely.
• Cannabis and alcohol, when taken together, intensify each other's effects and can cause severe impairment.
• Cannabis intoxication affects thinking and short-term memory. Using cannabis while at school or work may interfere with learning or work performance.
• Unless you have a medical exemption, it is illegal to grow, possess or sell cannabis.
• Illegal cannabis products are not subject to any health and safety standards, and may be contaminated with other drugs, pesticides or toxic fungi.
• Large doses of potent cannabis, especially when swallowed, can cause "toxic psychosis." Symptoms include auditory and visual hallucinations, paranoid delusions, confusion and amnesia. When cannabis use is stopped, these symptoms usually disappear within a week.
• Cannabis use raises the heart rate and lowers blood pressure. People with angina or other coronary artery disease may increase their risk of heart attack if they use cannabis.
• Using cannabis during pregnancy may affect the fetus. Research suggests there may be a link between cannabis use during pregnancy and subtle cognitive problems in children. Cannabis smoke contains many of the same chemicals found in cigarette smoke, which are dangerous to the fetus.
  

What are the long-term health effects of using cannabis?

People who use cannabis heavily or regularly, or people with certain medical or psychiatric conditions, risk the following possible long-term effects:

• Cannabis smoke contains tar and other known cancer-causing agents. People who smoke cannabis often hold unfiltered smoke in their lungs for maximum effect. This adds to the risk of cancer.
• Smoking cannabis irritates the respiratory system. Chronic marijuana smoking has been linked to bronchitis.
• • The constant intoxication associated with heavy cannabis use often reduces motivation for work and study, although this usually returns when drug use is stopped.
• • There is a possible association between heavy regular cannabis use and the onset of schizophrenia. It is not clear, however, whether cannabis use releases latent symptoms of schizophrenia, or whether people use cannabis to help them cope with the symptoms of an emerging psychosis. Evidence suggests that continued cannabis use in people with schizophrenia accentuates psychotic symptoms and worsens the course of the illness.
• • Chronic, heavy use of cannabis may impair people's attention, memory and the ability to process complex information for weeks, months and even years after they have stopped using cannabis.

Treatment from CAMH

Support Groups for Families

Ontario Drug and Alcohol Helpline  (open 24/7 for treatment anywhere in Ontario)

Call the Kids Help Phone at 1 800 668-6868

​Other CAMH resources about cannabis

About Marijuana: information for youth

The Health Effects of Cannabis

The Legal Sanctions Related to Cannabis Possession/Use Position Statement

Cannabis Resource Package