How cannabis affects you

Last revised: March 18, 2024

Not using cannabis is the best way to avoid these health effects. Short-Term Effects-Reactions to cannabis differ.

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

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.

Cannabis use can lead to mental health challenges.

Using cannabis can increase the risk of experiencing psychosis and schizophrenia. The risk increases if you are a teenager, use regularly, or someone in your family has or had these conditions.

Cannabis use impairs your ability to drive safe.

Cannabis containing THC can impair judgement, response time, attention and coordination. If you are 21 and under, there is a zero-tolerance law for impaired driving, meaning you cannot have any alcohol or substances (drugs) in your system. Plan a safe ride with a friend or use public transit and/or a ridesharing service.

For more information:

Cannabis smoke can be harmful to your lungs. 

Burning cannabis makes smoke that has the same harmful chemicals and carcinogens as cigarette smoke. The chemicals are not in the cannabis plant but are made from burning the plant material. Smoking cannabis often can lead to lung infections and chronic bronchitis.

Cannabis use can lead to dependence.

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 become cannabis dependent 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.

If you are concerned about your use or someone else’s use, there are places you can turn to for help.

Know where to go for help 

Don’t hesitate to get help if using cannabis is affecting your life. There are places to go to if you need help managing your use or if you have withdrawal symptoms.

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

Signs you may need help with your cannabis or other substance (drug) use include:

  • Ignoring responsibilities at work, school, or home.
  • Giving up activities that you find important or enjoyable.
  • Using the substance (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.

For more information on resources and services, visit our Mental Health, Addictions and Substance Use Health Services and Resources webpage.
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