Health effects of cannabis

Effects can be felt within seconds to minutes of smoking, vaporizing or dabbing cannabis. These effects can last up to 24 hours. If you eat or drink cannabis, these effects can occur within 30 minutes to 2 hours and can last up to 24 hours.

On this page

• Short-term health effects
• Long-term health effects
• Effects on different age groups
• Health effects during pregnancy and breastfeeding
• Potential therapeutic uses of cannabis

Short-term health effects

The flowers and leaves of the cannabis plant are used for their ability to cause effects on the mind, including:

• feeling high (euphoria)
• a sense of well-being
• relaxation
• heightened sensory experiences:
  • sight
  • taste
  • smell
  • sound

  While cannabis may make you feel relaxed and happy, your body and brain may also experience effects that are:

  • negative
  • unwanted
  • unpleasant

  Some of the short-term effects on your brain can include:

  • confusion
  • sleepiness (fatigue)
  • impaired ability to:
    • remember
    • concentrate
    • pay attention
    • react quickly

    Short term effects on your body can also include:

    • if smoking, damaged blood vessels caused by the smoke
    • decreased blood pressure, which can cause people to faint
    • increased heart rate, which can be dangerous for people with heart conditions and can lead to an increased risk of heart attack

    Cannabis use can also result in psychotic episodes characterized by:

    • paranoia
    • delusions
    • hallucinations

    Long-term health effects

    Long-term effects develop gradually over time, with daily or near-daily (weekly) use that continues over:

    The long-term effects of cannabis on your brain can include an increased risk of addiction. Long-term cannabis use can also harm your:

    • memory
    • concentration
    • intelligence (IQ)
    • ability to think and make decisions

    Effects appear to be worse if you:

    • start using early in adolescence
    • use frequently and over a long period of time

    These effects can last from several days, to months or longer after you stop using cannabis. They may not be fully reversible even when cannabis use stops.

    Other long-term effects of smoking cannabis are similar to the effects of smoking tobacco. These effects can include risks to lung health, such as:

    • bronchitis
    • lung infections
    • chronic (long-term) cough
    • increased mucus buildup in the chest

    Effects on different age groups

    Depending on your age, there are various factors to consider when deciding to use cannabis. Learn more about how cannabis affects:

    • youth aged 13–17 years
    • young adults aged 18–25 years

    Health effects during pregnancy and breastfeeding

    Just like with tobacco and alcohol, a pregnant woman or new mother's use of cannabis can affect her fetus or newborn child.

    The substances in cannabis are carried through the mother's blood to her fetus during pregnancy. They are passed into the breast milk following birth. This can lead to health problems for the child.

    Cannabis use during pregnancy can lead to lower birth weight of the baby. It has also been associated with longer-term developmental effects in children and adolescents, such as:

    • decreases in:
      • memory function
      • ability to pay attention
      • reasoning and problem-solving skills

      Potential therapeutic uses of cannabis

      There is some evidence of potential therapeutic uses for cannabis or its component chemicals (cannabinoids).

      • potential therapeutic uses
      • dosing
      • warnings
      • adverse effects

      For more information

      • About cannabis
      • Cannabis and mental health
      • Cannabis impairment and safety risk
      • Driving while impaired by a drug
      • Minimizing your risk when smoking, vaping and dabbing
      • Thinking about using cannabis before or during pregnancy?
      • Thinking about using cannabis while parenting?
      • What is chronic pain