Everything you want to know about pot: Your questions answered

The lowdown on getting high from CBC's White Coat, Black Art.
Sorry for the buzzkill, but there's no safe way to inhale cannabis smoke. (Dominick Reuter/Reuters)
Listen to the full episode26:29

CBC's White Coat, Black Art has the lowdown on getting high. 

You wanted to know: Is it safe to drive after using cannabis? Will pot help you sleep? Is marijuana healthier than alcohol?

We've got leading medical experts to answer these questions and more.

Is cannabis as hazardous as cigarettes?

Does breathing in the smoke from cannabis have the same hazardous effects as smoking cigarettes?

- Peter Austin, Oakville, Ont.

"The same thing tobacco does to the cells in your lungs, cannabis smoke exposure is going to do to your lungs as well," answered Jeremy Hirota, McMaster University's Canada research chair in respiratory mucosal immunology

Children are more susceptible to damage because their lungs are still developing.

Will pot help me sleep?

Can cannabis help me to sleep better? Will it leave me alert and clear headed during the day? Where can I get reliable, evidence-based answers?

- Frank Reiter, Maple Ridge, B.C.

Lots of people claim cannabis helps them to sleep better, but the scientific evidence is not yet there, said Dr. Benicio Frey, associate professor of psychiatry and behavioural neurosciences at McMaster University.

The concentration of THC over CBD might make a difference to daytime wakefulness. (Jason Redmond/Reuters)

In studies on marijuana's effect on people with chronic pain, Frey said that there is evidence that some slept better. What's not yet clear is whether they slept better simply because their pain improved or if marijuana serves as an effective sleep aid.

On whether you'll feel clear-headed the next day, Frey said a lot depends on the concentration of THC over cannabidiol (CBD).

One resource? The U.S. National Academies of Science, Engineering and Medicine report on medicinal cannabis.

Does marijuana interact with other drugs?

Are there any common drug interactions that I need to be aware of before using recreationally? 

- Rebecca Malo, Warman, Sask.

We had Kelly Grindrod, associate professor at University of Waterloo's School of Pharmacy, answer this question.

University of Waterloo's Kelly Grindrod on drug interactions 1:32

Does marijuana trigger psychosis?

I've been led to believe that one of the underestimated concerns regarding a more widespread access to marijuana is its ability to trigger psychotic episodes in those who are predisposed to them. Is this a legitimate concern?

- Mike Hrycenko, Dundas, Ont.

As the clinical director of the Cleghorn Early Intervention in Psychosis Program at St. Joseph's, Dr. Suzanne Archie sees young people with cannabis-induced psychosis.

Listen to the audio clip below as Archie and host Dr. Brian Goldman explore how that differs from having a diagnosis of schizophrenia or bipolar disease. Age, family history and high tetrahydrocannabinol (THC) content increase the risk.

Dr. Brian Goldman talks to Dr. Suzanne Archie, psychiatrist at St. Joseph's Healthcare Hamilton, about cannabis-induced psychosis. 1:05

Can I drive on pot?

How does being high on pot affect a person's ability to drive?

- Pearl Benyk, Yellowknife, N.W.T.

Michael Amlung, an assistant professor in the department of psychiatry and behavioural neurosciences at McMaster, studies impaired driving.

Driving simulator studies show people impaired by cannabis are lousy drivers, according to Amlung. 

They are more likely to miss cues like a bouncing ball popping into view before a child runs into traffic, said Amlung, and their reaction times are longer.

Psychiatrist Suzanne Archie sees young people with temporary cannabis-induced psychosis. (Amina Zafar/CBC)

But there's a dangerous mismatch between how impaired cannabis users perceive themselves and their performance, Amlung said.

There's a widespread attitude that marijuana affects your driving less than alcohol. That belief distorts the reality that driving while high is undoubtedly a dangerous practice.

What's more, there's no foolproof roadside test for marijuana impairment. The way our bodies slowly metabolize or break down cannabis makes it harder to measure impairment than for alcohol, said Amlung.

Is pot healthier than booze?

A couple of listeners in their early 60s asked how the daily use of cannabis affects one's health compared with using tobacco and alcohol daily.

Dr. Jason Busse, co-director of the Michael G. DeGroote Centre for Medicinal Cannabis Research, stressed there's no safe way to inhale cannabis.

But using a water-filled "bong" has some filtering advantages over a cannabis cigarette, said Busse.

The bong filters some of the particulates and water-soluble elements of the smoke.

But the science is still out on the long-term effects of cannabis use. It is not clear whether marijuana causes any damage to the heart, according to a review in Annals of Internal Medicine.

Since there are trade-offs between using the three substances, Busse recommended regular physical exams by your doctor.

And, Busse added a warning for those trying marijuana edibles.

While inhaling THC gives a high within minutes, edibles can take up to three hours, said Busse. That can lead people to ingesting too much and having a marijuana overdose.

How long does cannabis last?

What about shelf life of marijuana for therapeutic and medical use?

- Susan Nabors, Calgary, Alta.

White Coat, Black Art went to Michael Beazely, associate professor at University of Waterloo's School of Pharmacy, for the answer.

How long does cannabis last? University of Waterloo's Michael Beazely responds. 2:29

How long does THC hang around in the body?

Will THC "wash" out of users' brains and bodies?

- Stephan Grasmuck, Eganville, Ont. 

Yes, but slowly, said James MacKillop, co-director of the Michael G. Degroote Centre for Medicinal Cannabis Research.

He said that long after you smoke or ingest it, psychoactive THC can be released slowly over time from our fat cells.  

There are dozens of compounds beyond THC and CBD in pot, called the minor cannabinoids and scientists are interested in researching how they interact in the body.

"These interactions are called the 'entourage effect,' and that's a hypothesis, not a proven reality," said MacKillop.

"But one of the reasons there's interest in plant cannabis over the medical product is because there may be these interactions."

Grasmuck's question about how long it takes THC to "wash out" of the body and brain led to a debunking of why exercise won't help.

Watch MacKillop's response below.

Dr. Brian Goldman talked to McMaster University's James MacKillop. 0:47

Video: Cannabis and your health Q&A | Dr. Brian Goldman and CBC-TV's Heather Hiscox take your questions

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