Cannabis (Marijuana)

General Information/ FAQs

Q: What is cannabis?

A: Cannabis is a plant that contains chemicals called cannabinoids. The two main cannabinoids are THC and CBD. 

Q: What is THC?

A: Tetrahydrocannabinol (THC) is the psychoactive component in cannabis. It causes cognitive impairment, more commonly known as "the high." 

Q: What is CBD?

A: Cannabinoidol (CBD) is non-psychoactive. Research shows that CBD may decrease some of the psychoactive effects of THC.

Q: How is cannabis used?

A: Cannabis can be inhaled through smoking, vaping, or dabbing, and ingested in foods and drinks.

Q: What are edibles?

A: Edibles refer to food or drinks that contain active cannabinoids (THC, CBD).

Q: What are symptoms of cannabis poisoning?

A: Symptoms of cannabis poisoning include nausea, vomiting, chest pain, dizziness, sleepiness, anxiety, and psychosis.

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Health Effects

Short-Term Effects

Reactions to cannabis differ. Some of the possible short-term effects include:

  • Sleepiness
  • Impaired ability to remember, concentrate, and pay attention
  • Anxiety, fear, or panic
  • Reduced coordination, reaction time, decision-making abilities, and ability to judge distances
  • Psychotic episodes

Source: Health Canada

Long-Term Effects

Long-term effects develop gradually over time with frequent (daily or almost daily) use. Long-term effects are worse for youth who start using frequently and early because the effects may not be fully reversible when cannabis use stops.

Remember, it is never okay to drive under the influence of any substance. Find out what the Government of Canada has to say about it. 

Brain Development
Using cannabis before the age of 25 is associated with changes to the developing brain’s structure and function. This leads to difficulty with memory, concentration, intelligence, judgement, and decision-making.
Mental Illness

Cannabis use increases the likelihood of experiencing mental health problems (psychosis and schizophrenia).


Regular use can lead to a cannabis use disorder or dependence. The risk for dependence is higher for persons who use regularly and persons under 25. If you develop a dependence it will be hard to cut back or stop using. It can cause unpleasant feelings like:

  • Feeling irritable or anxious,
  • Having an upset stomach,
  • Trouble sleeping,
  • Loss of appetite and
  • Sweating.

Not using cannabis is the best way to avoid these health effects.

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Lower-Risk Use

These tips are based on Canada's Lower-Risk Cannabis Use Guidelines.

Start low, and go slow

Use products with low THC and an equal or higher amount of CBD. If you are smoking or vaping, start with 1 or 2 puffs of 10% (100mg/g) THC or less. The effects are usually felt within seconds to minutes. They may peak after 30 minutes, and they can last approximately 6 hours. If you are consuming edibles, start with 2.5 mg THC or less. The effects are usually felt within 30 minutes to 2 hours. They may peak after 4 hours, and they can last approximately 12 hours.

Go easy on your lungs

Cannabis smoke has many of the same chemicals as tobacco smoke. After you take a hit, it only takes a few seconds for the smoke to get to your lungs that absorb the THC. The high can peak after about 30 minutes and last up to 6 hours.

Ingesting or vaping cannabis are less harmful than smoking but be aware that these may have their own risks.

If you vape, watch for symptoms such as cough, shortness of breath and chest pain. Seek medical attention if you have concerns about your health. Only dried cannabis is legally available for use with a vaporizer.

If you choose to ingest cannabis (e.g. edibles, oils), review the Start Low. Go Slow section for more information.

Obtain cannabis from legal sources. Products from illegal or unregulated sources, are not subject to any controls for safety or quality.

If you smoke cannabis, avoid inhaling deeply or holding your breath. 

Secure your stash

Keep cannabis products in original or child resistant packaging. Make sure you put them somewhere that is out of reach of children and pets and in a container that has a lock. 

Stick to one drug at a time - leave tobacco out of the mix too

Using more than one drug at a time can lead to unpredictable changes in how you think, feel, and act. Tobacco contains nicotine that also has addictive qualities.

Plan a safe ride home

Cannabis impairs coordination, attention, judgement, and reaction time. Plan a safe ride home with a friend, Uber, Lyft, OC Transpo, or a taxi.

Pro-tip: calling #TAXI in the Ottawa area connects you to the first available taxi service. 

Share with care

Sharing joints, bongs, or vaporizers means you may also be sharing germs and infections from your mouth and saliva. Avoid sharing or find ways to use without direct contact to your lips.

Have more cannabis free days

Frequent cannabis use can increase the negative effects on your mind and body. Limit your cannabis use to one day a week at most.

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The Law

Here is a summary of the provincial law:

Minimum legal age 19 years old
Youth possession Ontario prohibits individuals under the age of 19 from possessing or consuming cannabis.
Giving or selling to youth

There are criminal penalties for giving or selling cannabis to someone who is under 19.

Public consumption Cannabis use is permitted in the same places where tobacco use is permitted.
Impaired driving Zero tolerance policy for young (21 & under), novice and commercial drivers. Sanctions similar to alcohol.

For more information, visit Ottawa Public Health’s Use Legally page or

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Ask for Help

If you are concerned about yourself or someone else, seek help from: 

Signs that you may need help with your cannabis use inclue:

  • Ignoring responsibilities at work, school, or home.
  • Giving up activities that you find important or enjoyable.
  • Using the drug more often.
  • Feeling unable to cut down or manage your use.
  • Changes in mood (e.g., feeling irritable and paranoid).
  • Changing friends.
  • Having difficulties with family members.
  • Being secretive or dishonest.
  • Changing sleep habits, appetite, or other behaviors.

Learn more about local resources.

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