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Canada's Lower-Risk Cannabis Use Guidelines

1. Cannabis use has health risks best avoided by abstaining

To avoid all risks, do not use cannabis. If you decide to use, you could experience immediate, as well as long-term risks to your health and well-being. Any time you choose not to use, you avoid these risks.

2. Delay taking up cannabis use until later in life

Delay taking up cannabis use until later in life. Using cannabis at a young age, particularly before age 16, increases the likelihood of developing health, educational and social problems. Avoid cannabis use during adolescence. Generally, the later in life you begin to use cannabis, the lower the risk of problems.

3. Identify and choose lower-risk cannabis products

High-potency cannabis products, with high tetrahydrocannabinol (THC) content, are more likely to result in harms. Some products contain a higher dose of cannabidiol (CBD), which counteracts some of THC's adverse effects. This means that products with high CBD-to-THC ratios reduce some of the risks. Know what you're using. Ideally, choose cannabis products with lower risk of harms.

4. Don't use synthetic cannabinoids

Compared with natural cannabis products, synthetic cannabis products (e.g., K2 or Spice) can lead to more severe health problems, even death. If you use, give preference to natural cannabis products and abstain from synthetics.

5. Avoid smoking burnt cannabis-choose safer ways of using

Smoking burnt cannabis, especially when combined with tobacco, can harm your lungs and respiratory system. Choose other methods, such as vaporizers or edibles instead-but recognize that they also come with some risks. For example, edibles are safer for your lungs, but you may consume larger doses and experience more severe impairment because psychoactive effects are delayed.

6. If you smoke cannabis, avoid harmful smoking practices

If you smoke cannabis, avoid "deep inhalation" or "breath-holding." These practices are meant to increase psychoactive experiences, but they increase the amount of toxic material absorbed by your lungs and into your body.

7. Limit and reduce how often you use cannabis

Frequent cannabis use (i.e., daily or almost every day) is strongly linked to a higher risk of health and social problems. Limit yourself-and ideally your friends or others you may be using with-to occasional use, such as on weekends or one day a week at most.

8. Don't use and drive, or operate other machinery

Driving while impaired by cannabis substantially increases your risk of being involved in a motor-vehicle accident resulting in injury or death. Don't use and drive, or use other machinery. Wait at least six hours after using cannabis-or even longer if you need. Combining cannabis and alcohol further increases impairment, so be sure to avoid this combination if you plan to drive.

9. Avoid cannabis use altogether if you are at risk for mental health problems or are pregnant

Some individuals should not use cannabis because of specific risk profiles. If you or an immediate family member has a history of psychosis or substance use disorder, your risk of cannabis-related mental health problems increases, and you should abstain from use. Pregnant women should not use cannabis because it could harm the fetus or newborn.

10. Avoid combining these risks

The more of these risky behaviours you engage in when using cannabis, the higher your risk of harms. For ex-ample, initiating cannabis use at a young age and smoking high-potency products every day puts you at much higher risk of both immediate and long-term problems. Avoid combining these high-risk choices.

Health Effects of Cannabis

The following information explains how the use of cannabis can affect your health. There is strong scientific evidence that cannabis use is associated with a variety of health risks. The risks depend on your constitution, which kinds of cannabis products you use and how or how often you use them. Some of the main health risks are:

• problems with thinking, memory or physical co-ordination
• impaired perceptions or hallucinations
• fatal and non-fatal injuries, including those from motor-vehicle accidents, due to impairment
• mental health problems and cannabis dependence
• reproductive problems
• chronic respiratory or lung problems

Your Brain

Cannabis includes the psychoactive (mind-altering) chemical THC (delta-9-tetrahydrocannabinol), as well as other related chemicals. When cannabis is smoked, THC passes through the lungs into the bloodstream, which carries the chemical to the brain and the other organs. The THC acts on specific receptors in the brain cells, and it interrupts normal brain development and function.

When used heavily by young people, cannabis has serious effects on brain development, particularly thinking and memory, which may be long lasting or even permanent. A long-term study in New Zealand showed that young people who were heavy smokers of cannabis in their teens lost an average of 8 IQ points between the ages of 13 and 38. Furthermore, the study showed that if people quit smoking cannabis as adults, the lost cognitive abilities were not fully restored.

Some of the effects of THC on brain function include distorted perceptions and mood, decreased muscle strength and coordination, difficulty concentrating and problem solving, and problems with learning and memory.

Your Mental Health

Numerous studies have connected frequent cannabis use and mental illness. In some users, high concentrations of cannabis can produce a temporary psychotic state, and schizophrenics who use cannabis can experience worsened symptoms of their illness.

Several large, long-term studies have also shown a correspondence between cannabis use and the development of schizophrenia. Researchers found this correspondence to be influenced by several factors: genetic background, the amount and potency of cannabis used, and the age at which cannabis was first used.

Links have also been found between cannabis use and other mental health problems, including depression, anxiety, suicidal thoughts, and personality changes.

Your Cardiopulmonary System

People who smoke cannabis frequently can have many of the same respiratory problems experienced by tobacco smokers, such as increased coughing and phlegm, chest illnesses, and lung infections. One recent study found that heavy cannabis users were twice as likely to develop lung cancer over a 40-year follow-up, after controlling for baseline tobacco use, alcohol use, respiratory conditions and socioeconomic status.

When a person smokes cannabis, his or her heart rate rises by 20-100 percent right after smoking, and the rise in heart rate can last up to 3 hours. Therefore, especially in the first hour after smoking, the risk of heart attack can be greatly increased. In one study, the risk of heart attack was estimated to increase nearly 500% during this time period.

Cannabis and Pregnancy

Babies whose mothers used cannabis during pregnancy may experience neuro-behavioural problems. Later complications for the developing child may include difficulties with memory, attention, and problem solving.

Potency of Cannabis Today

It is important to note that the amount of THC in cannabis has increased steadily over the past few decades. In the 1980s, THC concentration in cannabis was about 4 percent, while in 2012 it averaged about 15 percent. For frequent users of cannabis, it may mean a greater risk of addiction if they are exposing themselves to these higher concentrations of the drug. The consequences associated with higher potency levels of cannabis are not clear at this time, but exposure to these higher concentrations could have adverse or unpredictable effects on users' health.