Can You Donate Blood If You Use Cannabis?
Can You Donate Blood If You Use Cannabis?
Donating blood is one of the most impactful ways to contribute to public health. In the UK, however, fewer than 10% of eligible adults regularly donate. While many factors influence this, one common concern among medical cannabis patients is whether their treatment excludes them from donating blood.
As a CQC-registered UK medical cannabis clinic, we’re often asked: “Can I donate blood if I use cannabis?” The answer isn’t entirely clear-cut — but in this blog, we’ll explore the current NHS guidelines, the role of medical cannabis, and what patients need to know.
Contents
Blood donation in the UK: who is eligible?
Blood donation in the UK is managed by NHS Blood and Transplant (NHSBT), which sets strict eligibility criteria to protect donors and recipients alike.
To donate blood, you must:
- Be in good general health
- Be aged between 17 and 65
- Weigh between 50kg (7st 12lbs) and 158kg (25st)
- Have suitable veins (assessed during your appointment)
You cannot donate blood if you:
- Have certain heart conditions or cancers
- Are living with HIV or hepatitis B/C
- Have received blood products since January 1980
- Have had an organ transplant
- Have used non-prescribed injectable drugs
Cannabis use isn’t specifically listed as an exclusion — but being under the influence during your appointment could make you temporarily ineligible.
Can you donate blood if you use medical cannabis?
The short answer: yes, you may still be eligible. However, you must not be impaired at the time of donation. NHSBT’s main concern is whether the donor is able to give informed consent and whether there’s increased risk of side effects like dizziness or fainting.
Medical cannabis differs significantly from recreational use. Prescribed cannabis-based products for medicinal use in humans (CBPMs) are tightly regulated and typically dosed in a way that avoids intoxication.
Despite this, NHSBT doesn’t yet offer specific guidance for patients using prescribed cannabis. Each case may be judged individually depending on your prescription and the nurse overseeing your donation.
What about prescribed medications?
Being on medication doesn’t automatically disqualify you. Many common prescriptions — including antibiotics — require only a short deferral period.
In theory, prescribed medical cannabis could fall into this category, especially if it doesn’t cause impairing effects. Some patients have shared that they were able to donate after disclosing their prescription, provided they weren’t under the influence at the time.
However, experiences may vary depending on the staff member, donation centre, and your personal health profile.
Why is there confusion?
Cannabis remains a stigmatised and often misunderstood medicine — even though it’s been legal in the UK for eligible patients since 2018. Many people, including some clinicians, may still associate it solely with recreational use.
This can lead to hesitance, miscommunication, or uncertainty when patients try to do the right thing by disclosing their treatment.
The lack of concrete NHSBT guidance also reflects the need for further research on how medical cannabis interacts with blood donation and donor safety.
What should medical cannabis patients do?
If you’re a medical cannabis patient and want to donate blood, here’s what to keep in mind:
- You may be eligible — depending on your individual health and medication
- You must not be under the influence of cannabis at the time of donation
- Always disclose your medication during your pre-screening
- Staff may ask you to delay donation as a precaution
To be safe, call NHS Blood and Transplant at 0300 123 23 23 or use their eligibility checker before booking.
Still have questions?
At CB1 Medical, we believe that medical cannabis patients should be supported and informed — especially when navigating systems like blood donation.
As awareness grows, we hope donation policies will evolve to reflect the reality of modern, prescribed cannabis care.
In the meantime, our team is here to help you understand your treatment options, your rights, and how to speak openly with healthcare professionals.
Curious if you’re eligible?
Try our free Eligibility Checker to see if medical cannabis is right for you.
