Health Matters with Dra. Denise – Cannabis: The Low-Down on Getting High (part 2)

Health Matters with Dra. Denise – Cannabis:  The Low-Down on Getting High (part 2)

Effects on the Lungs

Chronic, frequent cannabis smoking causes toxic by-products (similar to those in tobacco cigarettes) to be released and inhaled. Using cannabis and tobacco together increases the risk of developing lung disease such as asthma, chronic obstructive pulmonary disorder (COPD) and lung cancer.

Mental Health

Daily or near-daily use of cannabis increases the risk of developing anxiety, depression, psychosis, and schizophrenia. Avoid using cannabis if you have a personal or family history of psychosis, schizophrenia, or bipolar disorder. While most cannabis users will not develop schizophrenia, those already at risk either from family history or other risk factors are more likely to suffer psychosis with cannabis. This is especially true if cannabis use starts when a person is young, or if a person uses cannabis frequently. Psychosis symptoms can persist even after cannabis use has stopped. Using cannabis for long periods of time greatly increases a person’s risk. With bipolar disorder, cannabis increases the likelihood that manic periods will be triggered.

Research has shown that teens with high levels of anxiety might start using cannabis at a younger age, and they may increase the amount and frequency of use more quickly than other teens. Teen girls who experience depression may also use larger amounts of cannabis more often than peers. There is conflicting evidence about cannabis and its effectiveness to treat anxiety, so talk to your health care provider if you are considering using cannabis to treat your anxiety or depression.


Cannabis can affect your ability to become pregnant by disrupting menstrual cycles or reducing sperm count.

Cognitive Effects: Poor memory, concentration, and motivation

Long-term frequent cannabis use has been associated with lower grades and poorer work performance. This is because it can negatively affect your memory, your ability to concentrate at school or work, and for some people will make it more difficult to become motivated.


While many believe it is not addictive, approximately 9% of users become dependent on cannabis (compared to alcoholism, which occurs in 23% of drinkers). The risk is nearly twice that if you start using cannabis as a teen or young adult. If you begin using it multiple times a week, the risk of becoming dependent increases to between 25 and 50%.

Signs of cannabis use disorder include:
·craving cannabis
·not completing important responsibilities at work, school or home;
·giving up important social or occupational activities
·using cannabis more often or in larger amounts to achieve the desired effects
·having difficulty cutting down on or controlling cannabis use

Withdrawal symptoms include irritability, anxiety, upset stomach, loss of appetite, disturbed sleep and depression.
If someone you know is struggling with a dependency, contact the youth addictions centralized intake service: 1-877-710-3999, or the Manitoba Addictions Helpline at 1-855-662-6605.


Contrary to popular belief, it is possible to overdose on cannabis. While not fatal, overdose can be quite uncomfortable and cause nausea, vomiting, sleepiness, confusion, disorientation, clumsiness/loss of coordination, fainting, dizziness, chest pain, fast, slow or pounding heartbeat, panic attacks, loss of contact with reality, paranoia, and seizures. These effects can take several hours to go away, depending on how the cannabis was consumed. The risk for overdose is especially high if you consume homemade edible cannabis products, as it is usually not possible to accurately measure your dosage. Since they take a while to take effect, people sometimes take a second dose thinking the initial dose was not enough, leading to an overdose.

This is why, it is important to start with lower doses of a product, and to take time between “puffs” or “hits,” or before taking more edibles. It is recommended to wait at least four hours before taking a second serving of edibles to avoid taking too much.

Seek immediate medical attention in case of overdose if experiencing chest pain, panic attacks or seizures.

If you have taken too much and find the effects overwhelming, and you are not experiencing chest pain, seizures, or a loss of contact with reality, make sure you are in a safe place and do not drive a vehicle or ride a bicycle. As the effects of cannabis wear off, you should begin to feel less anxious and uncomfortable.

For lesser symptoms, contact poison control (1-855-776-4766 or 1-855-7POISON), or Health Links – Info Santé (204-788-8200 or toll free 1-888-315-9257) for 24-hour advice.

If you choose to use cannabis, the only way to avoid these risks is to use it infrequently, taking breaks from using cannabis, using products with lower levels of THC and higher levels of CBD, and limiting the amount of cannabis that you use in a single day.


Remember: it is illegal to drive while impaired by a drug, including cannabis. Driving high can double the likelihood of having an accident. Consuming cannabis slows your reaction time, attention span, memory function, and other skills needed to drive safely or engage in other high-speed activities (like riding a bike, skiing, skateboarding). The risk is even greater when you add alcohol to the mix. Cannabis stays in your body even after you stop noticing its effects. You can still be impaired hours after you no longer feel high. If you have consumed cannabis, it is the safest decision not to drive until the next day. If you consume cannabis frequently, you may consistently have levels of cannabis in your body that make it illegal to drive, even if you do not feel impaired.

Impaired drivers can be charged and face penalties under the Criminal Code plus also receive sanctions, such as driver’s license suspensions, under the Highway Traffic Act. It is important for drivers, including those in the medical marijuana program, to be careful to not get behind the wheel if their ability to drive is impaired by a drug; otherwise, they pose a risk of injury or death to themselves and others and could face serious legal consequences.
Kung may tinanim, may aanihin; health starts at home. Alagaan ninyo ang katawan at kalusugan ninyo! Take care, and mind your health!

About Dr. Denise Koh

Dr. Denise Koh is Manitoba’s Chief Occupational Medical Officer and Medical Officer of Health in Environmental Health and Emergency Preparedness. She is a Public Health specialist with additional training and experience in Family Medicine and Occupational Medicine. Follow her writing at: