Ever wonder what effect marijuana really has on your health?

The Internet is full of claims about how marijuana affects health. You can find web pages that tell you that marijuana will decrease your IQ, and others that will tell you that marijuana will make you smarter. You can find websites that will tell you that marijuana will cause cancer, and others that will tell you that marijuana can cure cancer. If that’s not confusing, then I don’t know what is!

This blog post aims to clear up the myths around how marijuana impacts your health by giving you the facts. When we talk about facts, we’re talking about things that are supported by high quality research evidence as opposed to anecdotal evidence – you know, the kind you get from a friend of a friend who had a certain experience.

FACT: 5-9% of marijuana users will become dependent on marijuana. Lots of people say weed isn’t addictive – and it may not be for the majority of people who use it. Research shows that about 1 in 11 people who ever use marijuana will become dependent on it. People who start using it as youth and heavy users are even more likely to become addicted.

FACT: Using marijuana affects how your brain works. Marijuana contains lots of different chemicals that change the way your brain works. It can make people feel euphoric, relaxed and (sometimes) even hungry, but it can also have some negative impacts. Studies show that marijuana use affects verbal learning and memory for all types of users, at all levels of use. It also decreases your ability to pay attention and divide your attention among tasks. So, if you need to concentrate and remember things, you might want to hold off on the weed.

FACT: Using marijuana before driving doubles your chances of being in a motor vehicle collision. You may feel like pot makes you a better driver, but the truth is that marijuana causes you to perform worse on tasks that are crucial to driving, including: tracking, reaction time, visual function, concentration, short-term memory, dividing attention and handling unexpected events. The more THC (one of the active chemicals in marijuana) you consume, the more your risk of being in a motor vehicle collision increases. And if you use both marijuana and alcohol before driving, your risk of being in a collision increases even more than if you just used either one. If you’re going to get high, wait at least 3-4 hours before operating a motor vehicle, even if you feel fine. And to be on the safe side, just don’t use pot and drive.

FACT: Using marijuana that has high levels of THC can increase your risk of psychosis. There are lots of different types of marijuana that have different levels of THC and CBD, the most common chemical compounds. Research shows that the more THC you have in one sitting, the more at risk you are for experiencing an acute psychotic episode. That might include delusions, severe paranoia, hallucinations, or impaired speech or behaviour, among other symptoms, which can all be quite frightening, and sometimes require hospitalization. Watch out for high potency strains or products (e.g., cookies, candies) that may have high doses of THC in one serving.

FACT: THC can be passed from mother to baby during pregnancy and breastfeeding. THC is one of the psychoactive ingredients in marijuana. During pregnancy, THC used by a pregnant person can be passed to a developing baby through the placenta. If a person uses marijuana during breastfeeding, THC can be passed to the baby in the breastmilk. Because the effects of THC exposure on developing fetuses and babies has not yet been well studied, it’s best to avoid using marijuana during pregnancy and breastfeeding.

FACT: Marijuana is still illegal, unless you’ve got a medical prescription for it. This isn’t really a health effect, but I thought it was still an important point to make. Even though the federal government has committed to legalizing marijuana, it’s still currently illegal. This means that you can get in trouble with the law for having it, using it, sharing it or selling it. And those charges are criminal offenses which could have a huge impact on your life.

Overall, the health problems caused by marijuana are most serious for people who use it daily or start to use it at a young age. And although most occasional adult users don’t suffer serious pot-related problems, occasional use can still cause issues like motor vehicle collisions and injuries if used in a risky way. And of course, everyone who uses it has the chance of becoming addicted.

Luckily, some researchers at the Centre for Addiction and Mental Health (CAMH) have developed some lower risk cannabis use guidelines that can help you reduce your risks from using marijuana.

They recommend:

Abstaining from use to avoid health risks:

  • Especially if you are higher risk of cannabis‐related problems (e.g. personal or family history of psychosis, cardiovascular problems, or pregnant)

For those who choose to use marijuana:

  • Delay use until early adulthood (age 18 or older)
  • Avoid daily (or near-daily) use
  • Limit use of higher potency products to avoid intense impairment or psychosis symptoms
  • Avoid smoking cannabis and use less harmful delivery systems (smokeless systems like vapourizers)
  • Don’t operate vehicles or machinery for 3-4 hours after using cannabis – or longer if the effects persist (i.e., if you still feel impaired)