Can You Really Donate Blood If You Smoke Weed in Canada?

Can You Really Donate Blood If You Smoke Weed in Canada?

Smoking is one great way to relax. Donating blood is one great way to contribute to society, help the healthcare system, and get some extra health points for yourself. So, can you combine the two? 

The Rules Around Smoking Weed And Donating Blood

The Canadian Red Cross is not against donating blood if you smoke weed. They mention that people can donate blood even if they smoke cannabis.

Most clinics require donors to abstain from smoking or consuming alcohol and other substances for six hours before a donation so they don’t show up under the influence. 

In short, there are ways to donate blood even when you smoke weed.   


Q: Will I be tested for THC in my blood?

A: You’ll never be tested for THC content in your blood when you go to donate. 


Q: What if I have a high percentage of THC in my blood from consuming concentrates?

A: This still doesn’t make a difference. As long as you’re not impaired when you show up (which usually takes around 6 hours), you should be fine to donate.


Q: What about synthetic cannabis?

A: There are currently no guidelines on the use of synthetic cannabis and donating blood.

What Is The Half-Life Of THC?

The half-life of THC in blood is between 5 and 13 days, meaning that it takes up to about half of a month for half of the drug to leave the body. 

The effects of marijuana can sometimes linger in the body for up to three days after use, but most users will only feel the effects for one to two hours after smoking.

While the exact time frame depends on many factors, including how much you’ve smoked and what type of cannabis you use, it’s safe to say that it takes longer than you think for THC to completely vanish from your system.

The amount of time that THC stays in your system depends on several factors, including:

  • How much and how often you consume marijuana
  • Your metabolism rate (that is, how quickly your body breaks down chemicals like drugs)
  • How well you take care of yourself overall (your overall health)

If you’re a frequent user or someone who uses marijuana infrequently or recreationally — or even if you’re an occasional user — there’s a good chance that someone could get tested positive for THC months after last using it.

Even though the half-life of THC is up to 13 days, that doesn’t have an effect on your eligibility to donate blood.

What Are The Benefits Of Donating Blood?

If you have been thinking about donating blood, but have reservations about your drug use, there are a variety of reasons why you should go ahead and donate.


Donating blood is a great way to give back to the community, with each donation typically helping three people. 


The key is to be honest and upfront with your doctor when going in for your appointment so they can assess whether or not you’re eligible to donate. Donating blood is one way to do something positive for your health as well. 

When you put it like that, it’s hard to deny how important blood donation is in helping those who need it. It’s especially true given how many people are regularly encouraged by their doctors to donate because they know how important blood transfusions can be for treating a variety of illnesses and medical conditions. 

Can You Get High From A Blood Donation That Contains THC?

No, you can’t get high from a blood donor who has THC in their blood.

Your body has ways of filtering out foreign molecules like cannabis before they can reach your brain. It’s called the blood-brain barrier (BBB), and it works by restricting which substances can pass through its network of tight junctions between cells. 

The BBB is designed to keep out toxins and other harmful substances, but it also acts as a filter for drugs that enter your bloodstream. This means that if someone has THC in their blood, it won’t make its way into yours — even if you give them a pint of it.

IMPORTANT: The BBB works only with the “second-hand” high, it won’t work if you smoke weed yourself. There’s an extreme difference in the amount of active substance you get from weed first-hand or in a form of “contact-high”.

That’s why you CAN get high yourself, and can’t get the person who’ll receive your donated blood high this way. 

Final Thoughts

With so many benefits to donating blood, there is almost no reason not to do so. It doesn’t matter if you smoke cannabis or not. You’ll still be able to donate blood safely and effectively.

Related Articles