Effects: The Long and the Short of It

It’s not just about chillaxing. There are both short- and long-term effects of cannabis use. Some effects can be pleasant, unpleasant, or potentially harmful. How cannabis affects you may be different for someone else. Effects can vary especially for people under 25 years of age.

In addition to age of initiation, other factors that shape one’s experience with cannabis and level of risk include:


  • Personal physiology (can’t be sure how your make-up will react)
  • Personal and family mental health history (mental illness history = increased risk)
  • The frequency of use (increased frequency = increased risk)
  • How it’s consumed (various methods have different associated risks)
  • How much is consumed (more THC = increased risk) 
  • Product form (concentrates = increased risk)



Research to date, on the effects and risks associated with weed is based on cannabis with much lower THC levels than what is available today. Future research may show negative effects are greater when high concentrations of THC are consumed. 

Short-term Effects

Short-term effects after consuming weed may include:


  • Feeling happy, euphoric, outgoing
  • Heightened senses
  • Feeling hungry (the “munchies”)
  • Feeling relaxed or sleepy
  • Reduced reaction time, motor coordination, judgment of distance and time, ability to make decisions, concentrate, memory, and impaired risk-taking judgments (why driving high is not a good idea!)
  • Red eyes
  • Confusion, panic, anxiety (experienced by 1 in 4, more likely among new vs. experienced users)
  • Nausea, vomiting
  • Psychotic episode (hallucinations, hearing and seeing things that aren’t really there)
  • Decreased blood pressure, which causes some people to feel dizzy and faint
  • Increased heart rate, which could be dangerous for people with known or unknown heart conditions 
  • Body tremors


CAUTION: Short-term effects can be increased if alcohol or other substances are consumed on the same occasion. 

Long-term Effects

Using cannabis frequently, over time, and before the age of 25 (especially before age 16) increases your chances of experiencing negative long-term effects. You may experience some, none, or all of the following:


  • Reduced memory, learning, and attention
  • Poorer decision-making about all aspects of your life (school, relationships, activities)
  • Chronic cough and bronchitis, if smoked
  • Social anxiety
  • The onset of schizophrenia or other psychoses (especially with family history of schizophrenia)
  • Cannabis Use Disorder (CUD) which can range from mild to severe physical/psychological/social issues associated with frequent, regular use (dependency and addiction)
  • Withdrawal when frequent use stops

Negative long-term effects may reverse after use stops.

Despite popular belief that “you can’t get addicted to weed,” the truth is you can develop a problematic dependence.

If you or someone you know have signs of dependence, or have tried to stop without success there are supports to help cut back, or quit:

Cannabis withdrawal symptoms, which peak within the first week of quitting and can last up to two weeks, may include:

  • Irritability
  • Difficulty sleeping
  • Decreased appetite
  • Restlessness
  • Cravings
  • Nausea
  • Abdominal pain

If you or someone you know experiences withdrawal and symptoms persist or become difficult to manage, talk to a health care provider for assistance.