Medically Reviewed by
Jason Crawford

Article Last Updated on January 12, 2023

Donating blood is one of the best things you can do to help a fellow human being. Thanks to volunteers, millions of people receive blood transfusions that save them and improve their quality of life. There are many humane people who give blood on a regular basis, and while most of them are eligible for blood donation, there are certain restrictions.

One commonly asked question in the cannabis community is whether you can donate blood if you’re a marijuana user. Seeing as THC tends to linger in your system, a lot of cannabis users shy away from giving blood when they see a blood drive nearby because they assume they might be unqualified.

But, wonder no more. The short answer to this question is that smoking weed doesn’t disqualify you from being a blood donor, but, there are some grey areas.

In this article, we’ll discuss how weed behaves in your system, and we’ll touch upon the blood donation process and give you some informed tips on how to prepare. So, stay put and keep on reading.

Cannabinoids THC and CBD and Their Effects

The marijuana plant is made up of over 400 different compounds, the most well-known being the cannabinoids delta-9-Tetrahydrocannabinol (THC) and Cannabidiol (CBD). Their molecular structure is the same, but they have differences in the arrangement of their atoms, which makes them affect the body differently.

The main difference between them is that THC is psychoactive, i.e. it gets you high, while CBD doesn’t. This is why you’ll mostly find CBD prescribed for inflammation, pain, depression, and anxiety, among other conditions. THC, on the other hand, causes relaxation, fatigue, and it alters your senses.

When they enter the bloodstream, CBD and THC are metabolized in the liver and then stored in the fat cells because they are fat-soluble. The higher your BMI (body mass index) is, the more cannabinoids your body will be able to absorb. The way they are processed is mostly dependent on the amount of weed you smoke, its strength, and your body’s tolerance and metabolic rate.

How Long Does Weed Stay in Your System?

Being fat-soluble makes cannabinoids a little harder to leave your system in a short amount of time. How long the weed stays in your body is entirely dependent on your weed habits. The presence of drugs is measured by the number of weed metabolites present in the system which remain detectable even after the effects have worn off.

So, for example, the results will be different for someone who smokes the occasional joint at a get-together and someone who’s using medical marijuana or regular cannabis on a daily basis. Therefore, chronic use of weed will certainly make it more detectable and able to stay in your bloodstream for longer compared to recreational cannabis use.

More specifically, occasional users will have traces of weed in their system 3 days after use, moderate users about a week, chronic users (daily) about two weeks, and heavy chronic users (multiple times a day) can have traces of weed in their system for up to four weeks. (Verstraete, 2004)

But does this matter to your local blood bank at the time of donation?

Do They Check Your Blood for the Presence of THC?

When thinking about donating blood, most cannabis enthusiasts are worried about whether their blood will be tested for the presence of THC. You should know that even though each donor’s blood goes through several lab tests and procedures before it is added to the blood supply, an FDA-ordered THC test is not one of them. The good news is that this information is confirmed in the FAQ section on the website of the American Red Cross. Therefore, you do not need to be worried about your weed use being a cause of deferral in the United States.

However, this information mostly applies to smoking marijuana. In their FAQ section, they also state that there are some concerns regarding prescribed synthetic marijuana, as some varieties “have been found to contain certain anticoagulants known to contaminate plasma.” For this reason, the final decision regarding donations from synthetic marijuana users will be up to each individual blood donation center. There is no additional info on other illegal drugs.

So, Can You Donate Blood If You Smoke Weed?

From what we’ve discussed above, it can be concluded that as long as you’re in good health and don’t have a serious medical condition, you are a potential donor. There are other disqualifiers for giving blood that don’t include smoking pot, like using injectable drugs. 

However, be mindful. Even though you won’t be tested for THC presence, the blood bank will need your full, sober consent and accurate information to fill in the form. If you show up to your appointment shortly after smoking a joint and are visibly under the influence, there is a strong possibility that your memory or comprehension will be impaired and you’ll be asked to come back another time.

Therefore, if you can’t skip taking weed that day, we recommend you wait at least until the effects have started wearing off before heading to your blood donation appointment.

Now that we’ve cleared that up, let’s look at some information on the process itself.

Can You Donate Plasma If You Smoke Weed?

According to the American Red Cross, the guidelines for cannabis users donating plasma are the same as those for donating whole blood. That means that as long as you’re feeling healthy and aren’t under the influence of weed, meaning you’re capable of giving sober consent for plasma donation, you won’t be turned down. However, some blood banks have some restrictions regarding the use of non-prescription synthetic marijuana because they could contaminate plasma. In this case, you should contact the support center and talk to a medical professional.

How Does the Blood Donation Process Go?

So, we’ve established that the legal or illegal use of marijuana doesn’t affect your eligibility. Let’s talk about the donor screening process. 

You will need to show your ID for registration and they’ll provide you with some info on giving blood. Next, you’ll talk to a medical professional and answer some questions regarding your medical and travel history, and then there’s a mini-physical exam where they’ll take your blood pressure and check for other vital signs.

Then it’s time for giving blood. You’ll be seated comfortably in a chair where a pint of blood will be drawn. This process usually lasts about 15-20 minutes, after which they’ll give you some refreshments before you’re ready to leave and move on with your day.

General Qualifications and Disqualifiers for Giving Blood

There are some specific disqualifiers for donating blood, like taking blood thinners, having an inherited blood clotting disorder, or having traveled to a high-risk country (in which case there is a waiting period). Alcohol use, cigarettes, and illicit drugs won’t disqualify you as long as you’re feeling well. For more on specific disqualifiers, you can check the American Red Cross eligibility criteria here.

However, whether you’re a weed smoker or not, there are general requirements you have to meet to be an eligible blood donor:

  • You must be 17 or older, though in most states you can donate at 16, but you will need parental consent;
  • You must be in good health and feeling healthy at the time of the donation. This means you shouldn’t go if you don’t feel capable of performing normal daily activities;
  • Your weight must be at least 110 lbs;
  • If you’ve donated blood in the past year, it can’t be sooner than 56 days.


Donating blood is a wonderful way to help someone in need. There is often doubt about whether marijuana users are qualified to give blood so a lot of people in the community often back away. However, the good news is that there are no restrictions for weed smokers, provided that they show up to their appointment when they’re not under the influence.

The important thing is the blood donated from one donor could save the lives of up to three people, so if you want to give blood, don’t shy away from it, any blood donation company will be happy to welcome you. And don’t forget to bring extra snacks.

Additional Sources

Verstraete, A.. “Detection Times of Drugs of Abuse in Blood, Urine, and Oral Fluid.” Therapeutic Drug Monitoring 26 (2004): 200-205. doi:10.1097/00007691-200404000-00020

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.