Cannabis and Health Effects
Cannabis can be harmful to mental and physical health, especially if someone uses:
- While under the age of 25
- Often, daily or near daily use
- With other drugs, like tobacco or alcohol
- High THC (delta-9-tetrahydrocannabinol) strains
- While pregnant or breastfeeding
- While operating a motor-vehicle
Short-Term and Long-Term Effects
When making a decision about using cannabis, it’s important to consider the short-term and long-term health effects.
Cannabis can be felt within seconds to minutes of smoking, vaporizing or dabbing and these effects can last up to six hours or longer.
The effects of eating or drinking cannabis can be felt within 30 minutes to two hours and can last up to 12 hours or longer.
Some key factors to consider when using cannabis are:
- The effects on both the mind and body
- Makes it harder for you to learn, concentrate and remember things
- Affects your mood and feelings (e.g. anxiety, fear or panic)
- Affects mental health (e.g. triggers paranoia, delusions or hallucinations and psychotic episodes)
- Impairs your ability to drive safely or operate equipment as it reduces your ability to react quickly
Canada’s Lower Risk Cannabis Use Guidelines
There are risks of using cannabis for immediate and long-term health. The main risks include cognitive and memory issues, hallucinations and impaired perception, impaired driving, injury and death, mental health problems, a dependence on cannabis, breathing problems and problems with the development of a baby when used during pregnancy and breastfeeding.
- The safest choice is no cannabis use at all.
- Delay the use of cannabis until later in life. Using cannabis at an earlier age increases health and social issues.
- Choose lower risk cannabis products with lower tetrahydrocannabinol (THC) levels.
- Avoid synthetic (man made) cannabinoids as they have higher THC levels.
- Avoid smoking cannabis and choose safer methods of using.
- If you do smoke cannabis avoid deep inhaling and breath holding.
- Reduce and limit the amount of cannabis you use.
- Wait six hours after using cannabis before using any type of vehicle or machinery.
- Do not use cannabis if you are pregnant, breastfeeding or you are at risk of mental health problems.
For more information, see Canada's Lower-Risk Cannabis Use Guidelines.
Cannabis Use While Pregnant and Breastfeeding
Cannabis use during the reproductive years can have negative effects on both you and your baby. Do not use cannabis when you are trying to get pregnant, are pregnant, breastfeeding or parenting your child.
Cannabis can affect you and your partner when you are trying to become pregnant by:
- Changing your menstrual cycle
- Lowering sperm count
- Reducing sperm quality
Cannabis crosses the placenta and your baby absorbs the chemicals that are in cannabis. Do not use cannabis while you are pregnant. If you are using cannabis for nausea, talk to your doctor about safe alternatives that are less risky to your baby’s growth and development.
Some immediate effects of cannabis use during pregnancy include:
- Low birth weight
- Pre-term birth
- Lower IQ scores
- Impulsivity and hyperactivity
- Brain development slows
Some effects of cannabis use during pregnancy that affect your child later in life include:
- Decreased ability to self-soothe
- Sleep disturbances
- Poor memory
- Attention difficulties
- Hyperactivity and impulsivity
- Difficulty learning
- Depression and anxiety
- Reduced school performance
- More likely to start using substances
Breastfeeding is the healthiest choice for your baby. Do not to use cannabis while you are breastfeeding. Cannabis passes into the breast milk and is taken into the baby’s fat cells and their brain.
Cannabis can affect your breastfed baby by:
- Slowing baby’s movements and responses
- Slowing baby’s brain development
- Baby becoming sedated
Cannabis can affect breastfeeding by:
- Lowering mother’s breast milk supply
- Baby having poor suck
- Baby becoming drowsy
- Cannabis: Implications For Pregnancy, Fetal Development and Longer-Term Health Outcomes
- Clearing the Smoke on Cannabis Highlights
- Health Effects of Cannabis (webpage)
- Risks of Cannabis on Fertility, Pregnancy, Breastfeeding and Parenting
- Your Cannabis Questions Answered