Cannabis Made Clear
Cannabis on Campus
Whether you puff or pass, get the unbiased info you need to make informed decisions around consuming cannabis.
Last updated October 2, 2025 | Published on October 2, 2025
While cannabis can be legally consumed at age 19 in Ontario, we know some people may encounter it earlier. Building your health literacy can help you make informed, thoughtful decisions that are right for you.
Some students choose to consume cannabis, some don’t — either way, this guide shares information to help you reduce risks, stay safer and better understand cannabis use.
Legal cannabis: What you need to know
Minimum legal age: 19 years old
Where to buy cannabis:
- Online from the OCS (OCS.ca) or Authorized Cannabis Store website
- Authorized Cannabis Stores, which are regulated by the Alcohol and Gaming Commission of Ontario (AGCO)
Look for the seal to be sure you’re buying from a legal source. Outside every Authorized Cannabis Store in Ontario, you’ll see the Cannabis Retail Seal displayed somewhere near the entrance. The seal must also be prominently displayed on any authorized website, app or other digital platform.
Buying from legal sources ensures the product is tested, labelled and free from contaminants.
How much you may carry
The possession limit — how much one person can carry In public — is 30 grams of dried flower, or its equivalent.
- 30 g dried flower
- 7.5 g concentrates (solid or liquid)
- 450 g edibles
- 2,100 g non-solids, such as oils
- 48 x 355 ml beverage cans
- 30 cannabis plant seeds
Where you can consume cannabis in Ontario
In Ontario, cannabis use is generally allowed where tobacco smoking is permitted. This includes:
- most private dwellings
- many outdoor public spaces, such as sidewalks and parks (at least 20 metres away from schools and playgrounds)
You can’t consume cannabis in a car even if parked. Cannabis should always be stored safely, out of reach of drivers.
Universities, colleges and rental landlords can set stricter rules about where cannabis can be consumed.
Travelling outside Canada?
Never bring cannabis or cannabis products — including CBD-only and medically authorized cannabis products — with you across any international border by car, plane or boat. This includes layovers and even when travelling to places where cannabis is legal or decriminalized.
Cannabis products and how they work
Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the two main cannabinoids found in cannabis.
- THC is known for having an intoxicating effect or producing a “high.”
- CBD is non-intoxicating and may reduce some negative effects of THC.
Cannabis comes in many strains or cultivars, each with different potencies, flavours and characteristics.
PRODUCT TYPE |
HOW IT’S USED |
HOW FAST EFFECTS START |
HOW LONG EFFECTS LAST |
|---|---|---|---|
| Dried Flower and Pre-Rolls | Inhaled | Within minutes | 2–4 hours |
| Vapes | Inhaled | Within minutes | 2–4 hours or more |
| Edibles (such as gummies and chocolates) | Eaten | 30 minutes to two hours | 6–8 hours or more |
| Beverages | Ingested | 10 minutes to one hour | 2–8 hours or more |
| Oils and Capsules | Swallowed | Up to two hours | 6–12 hours |
| Topicals | Applied to skin | Non-intoxicating — doesn’t produce a “high” | Localized effects |
Edibles and beverages may have a delayed onset. Accidental overconsumption (or “greening out”) happens because people don’t feel effects right away and consume more.
Health effects
While research is still developing in many areas related to cannabis, there are a few health risks to consider.
Brain development
The brain continues developing until about age 25. Regular cannabis use may affect attention, planning and memory.
Lung health
Smoking cannabis can irritate the lungs and lead to chronic coughing or bronchitis.
Heart health
Cannabis smoke can stress the heart and raise the risk of heart problems, especially with frequent use and for those with a family history of heart conditions.
Mental health
Research suggests cannabis may either relieve or worsen symptoms of anxiety, depression and psychosis, depending on the individual. The risks of developing psychosis or schizophrenia are highest for people with a family history of these mental health conditions and those who consume daily or more often.
Cannabis use disorder
Regular or heavy cannabis consumption can lead to cravings, loss of control and continued use despite negative impacts. Risks are higher for those who start before age 18 and consume frequently.
Impairment
Driving after cannabis use is illegal and dangerous. For drivers under 21 or with a G1, G2, M1 or M2 licence, Ontario law allows zero THC in your system. How long THC stays in your system depends on several factors, like how often you use cannabis, the amount you consume and your metabolism.
Mindful consumption
“Set and setting” is a simple mindfulness technique that may help reduce the harms of consuming cannabis. Consider how your mood and the people you’re with can impact how you feel about a meal or a movie. In the same way, your mindset (or “set”) and setting (for example, among friends or at home) affect how you feel when consuming cannabis.
Common cannabis myths, demystified
MYTH #1 “Cannabis is natural, so it’s harmless.”
Reality: While cannabis comes from a plant, it contains compounds like THC that may affect your brain development and lung, heart and mental health. Research shows that using cannabis regularly, particularly before age 25, could have health risks — even though many people may not experience significant negative effects.
MYTH #2 “I drive better when I’m high.”
Reality: Evidence shows cannabis use impairs attention, coordination and reaction time. It can also distort your perception of time, distance and speed, making driving less safe, even if you feel confident behind the wheel.
MYTH #3 “Cannabis isn’t addictive.”
Reality: Some people can develop cannabis use disorder, particularly with early, frequent or heavy use. While most will not develop problematic patterns, regular use can lead to cravings, difficulty controlling your consumption and continued use despite negative impacts.
MYTH #4 “Edibles are safer than smoking.”
Reality: Consuming edibles means avoiding the risks associated with smoke inhalation, but they carry other risks. Because edibles take longer to take effect, it’s easier to accidentally consume too much, leading to stronger and longer-lasting intoxication, including unpleasant effects (a.k.a., “greening out”).
MYTH #5 “Everyone my age uses cannabis.”
Reality: While cannabis use is relatively common among young adults, most are not daily or frequent consumers. In Ontario only 13% of 20- to 24-year-olds and 8% of 16- to 19-year-olds report consuming cannabis daily or almost daily. Choosing not to consume cannabis is just as common and completely valid.
Harm reduction tips
- Start with low-THC products (2.5 mg THC is a standard dose for edibles and beverages) and wait before consuming more.
- Always choose legal, tested products.
- Consume cannabis in a safe environment with trusted friends.
- Stick to one substance — don’t mix cannabis with alcohol, tobacco or other substances.
- Stay hydrated and eat beforehand.
- Take regular breaks from cannabis use.
- Get home safely. Never drive or bike under the influence.
- Store cannabis safely, away from children and pets.
- Monitor how cannabis is affecting your daily life, including your academics, extracurriculars like sports, work and relationships.
Cannabis use on campus
Campus rules vary, so always check your Institution’s policies. Generally:
- Most campuses prohibit smoking cannabis (and tobacco) on school property and in residences.
- Medical cannabis accommodations may be available — contact your school’s health or Accessibility office.
Want to learn more?
Contact your campus health and wellness centre or counselling services, or try these free resources.
- Cannabis Made Clear: Reliable, evidence-based education about responsible cannabis use, health effects and legal use
- ConnexOntario: Free, confidential mental health and addiction support
- Good2Talk: Free 24/7 student helpline
