What is it?

Cannabis can come in three forms: marijuana being the most common, hashish, and hash oil (CAMH, 2009). They all come from a plant called cannabis sativa which is a type of hemp plant (CAMH, 2009). The main psychoactive component of cannabis is THC (tetrahydrocannabinol). This chemical can change the way you think, feel, and act. It is considered a mixed effect drug meaning that it can act as a stimulant or depressant on the central nervous system (CNS), and it can also have hallucinogenic properites (K. Lomp, ADDC 1510 lecture, March 27, 2012). Cannabis is the most used illegal drug in Canada (CAMH, 2009).

Statistics (taken from CAMH, 2009)

  • 44% of Canadians report using marijuana at least once in their lifetime
  • 26.5% of students in Ontario grades 7-12 reported using marijuana in the past year, 31% reported using it at least once in their lifetime (2005)


  • Students in Toronto use marijuana less (20%) than students in the north (33%) and west (29%) of Ontario
  • In the past year 3% of grade 7 students used marijuana in Ontario, 46% will use marijuana by the time they are in grade 12 and report using it in the past year
  • 1 in 8 students in Ontario use marijuana every day, this represents 3% of all students grade 7-12 (33, 200)


Common Street Names
Weed - Bud - Joint - Mary Jane (MJ)
Herb - Blunt - Pot - Ganja
Chronic - Doobie - Grass - Dope
Jay - Hydro - Reefer - Spliff

How is it Used?

  • Almost always smoked
  • Can be taken orally (i.e., hash brownies)

What are the Effects? (CAMH, 2009)

Each person is affected differently. The factors contributing to this are:
  • How much is used (low dose: stimulant, moderate dose: depressant, high dose: hallucinogenic)
  • How strong it is
  • How often it is used
  • How it is used
  • A person’s mood or perception of what is supposed to happen
  • If a person has taken other drugs as well

The common effects are:

  • Feeling relaxed OR feeling more anxious, confused, or paranoid
  • More outgoing and talkative OR more quiet and withdrawn
  • Feeling giddy and laughing more- Time passes slowly
  • Have keener senses
  • Trouble keeping your balance
  • Trouble thinking, remembering (short-term), and doing tasks
  • “Munchies” (want to eat a lot)
  • Sore throat/chest
  • Dry mouth and red eyes
  • Increased heart rate
  • “Burnout” (become sleepy)
  • Hallucinate (less common)
  • Impairments in attention and memory which interferes with complex visual-motor skills (i.e. driving an automobile)

These acute effects are quite rapid (peaks within 5-10 minutes), however because cannabis is absorbed through fatty tissue, its elimination is very slow (K. Lomp, ADDC 1510 lecture, March 27, 2012). It may require days, even weeks, for the THC to leave the body completely (K. Lomp, ADDC 1510 lecture, March 27, 2012). The high usually lasts up to 2 hours (K. Lomp, ADDC 1510 lecture, March 27, 2012).

Tolerance, Dependence, and Withdrawal

Tolerance does develop in regular users however it is very subtle (K. Lomp, ADDC 1510 lecture, March 27, 2012). The dependence liability for marijuana is also fairly low (K. Lomp, ADDC 1510 lecture, March 27, 2012). There is no evidence of cannabis withdrawal but research does suggest that an abstinence syndrome may exist, with symptoms that include; anxiety, irritability, disrupted sleep, decreased food intake, and aggressive behaviour that can last from 4-12 days (K. Lomp, ADDC 1510 lecture, March 27, 2012).

How is it Harmful?

Marijuana can become addictive and some people will need to find treatment to help them quit (CAMH, 2009). A physical dependence can develop; therefore when a person who uses a lot of marijuana everyday suddenly stops using it, they will experience withdrawal symptoms (CAMH, 2009). However these symptoms usually only last a few days. A few of the symptoms experienced include:
  • Feeling anxious, irritable, or nervous
  • Have problems sleeping
  • Upset stomach
  • Loss of appetite

sharma-obesity-cannabis_leaf3.gifMarijuana contains at least 400 chemicals (CAMH, 2009). When smoking marijuana, there is more tar and more cancer-causing chemicals than smoking tobacco (CAMH, 2009). People who inhale the marijuana smoke more deeply and hold it in their lungs to get more high are at an increased risk of developing cancer (CAMH, 2009). In fact, it has been associated with cancers in eight areas of the body (Reece, 2009). It has also been known to cause chronic coughing, bronchitis, and worsen asthma. Women who smoke marijuana while pregnant increase the chance that their baby will have a low birth weight. Cannabis has a teratogenic influence on brain development after it is used around the time of birth (Reece, 2009). Marijuana can also cause an early onset of schizophrenia in people who are at high risk of developing the illness (CAMH, 2009).

Long term use of marijuana makes it harder to concentrate, remember things, learn new things, affects decision making, decreases motivation, affects coordination, and slows down reaction time (CAMH, 2009). This makes it dangerous to drive a vehicle or operate machinery. Large doses of marijuana are known to cause something called “toxic psychosis” in which people hallucinate, become extremely paranoid, and believe things that aren’t true (CAMH, 2009). These symptoms will stop within a week if the person stops using marijuana (CAMH, 2009).

Other physical implications of long-term cannabis use include: respiratory ailments such as decreased lung density and lung cysts and heightened rates of heart attack and arrhythmia (Reece, 2009).

Legal Issues

Possession of and “trafficking” (selling) marijuana is illegal in Canada. First time convictions for possession under 30 grams can lead to jail time and fines up to a thousand dollars (CAMH, 2009). However, most first time offenders are discharged and receive only a small fine (CAMH, 2009). It does still leave you with a criminal record. Consecutive possession charges include longer times in jail and higher fines (CAMH, 2009). Trafficking, especially across borders, has a maximum penalty of life in prison (CAMH, 2009).

Medicinal Uses

Marijuana has been found to relieve nausea and vomiting, and causes people to have an increased appetite (CAMH, 2009). This is useful for people who have AIDS or cancer. THC is synthetically made and medically prescribed to these patients (CAMH, 2009). The government has also allowed people to grow their own marijuana but for medical purposes only (CAMH, 2009). People who are caught growing marijuana for non-medical purposes can receive up to 7 years in prison (CAMH, 2009). Marijuana can also be used as a pain reliever but is less effective than other drugs commonly used for pain.

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