Can THC Help Prevent Transplant Rejection?

Tens of thousands of organ transplants help to save lives every year. However, it’s not always a happy ending. Complications, especially transplant rejections, can prevent the transplant from being a long-term success. Research shows us how THC may help prevent the immune system from rejecting a transplant.

Organ transplants have saved, and continue to save, thousands of lives every day around the world, but ensuring everything goes well isn’t as easy as it sounds. The main problem we must tackle is that our bodies are programmed to use our immune system to protect themselves from any external attacks. That includes transplanted organs.

The immune system can trigger a reaction or transplant rejection, which can have fatal consequences. However, a 2015 study by Nagarkatti and colleagues suggests that tetrahydrocannabinol (THC) can help delay the rejection of transplanted organs or tissues in rodents. THC is one of the best known and best studied cannabinoids, responsible for many, if not most, of the physical and psychoactive effects of cannabis.

The legalisation of medicinal, as well as recreational, cannabis is a prominent issue in many countries around the world. Some have already legalised it while others are in the process of doing so, or starting discussions regarding this issue.

Every day, more studies emerge that demonstrate and publicise the numerous medical and therapeutic benefits of the cannabis plant, and the cannabinoids it contains.

These studies help to dispel the misgivings of those who continue to oppose the legalisation of cannabis. They also highlight the need to make continued progress in scientific research so that such studies may be conducted in a clinical setting, but with human subjects.

Some of the more recent studies concern surgery. In this article, we’ll specifically focus on one of the most interesting ones published in 2015, adding another benefit to an already long list for cannabis and more specifically the cannabinoid THC.

The therapeutic value of THC

In 2015, a group of researchers from the Faculty of Medicine at the University of South Carolina published a study to test the effects of THC on skin grafts. According to this study, tetrahydrocannabinol (THC), one of the main compounds of the cannabis plant, can help delay rejection in incompatible organ transplant patients by activating cannabinoid CB1 receptors in immune cells.

 “More and more research is identifying potential beneficial effects of substances contained in marijuana, but a major challenge has been identifying the molecular pathways involved,” said John Wherry, deputy editor of the magazine Journal of Leukocyte Biology, in a statement.

The ability of THC to regulate the immune system was first identified in the 1970s. Following a series of tests conducted in rodents, the research by Nagarkatti and colleagues now suggests that THC may improve the outcome of organ transplants by blocking the immune response that causes the transplanted organs to be rejected.

As a result, more lives could be saved through transplants. Clearly, this provides yet more evidence of the obvious therapeutic potential of cannabis. This is particularly true for THC, which together with CBD, is the most studied natural cannabinoid.

Organ transplantation: what does it involve?

Organ transplants are one of the most significant examples of scientific progress in medicine today. When organs or tissues begin to fail due to illness, it may be necessary to replace the diseased organ or tissue. To do so and in order to prolong lives, there needs to be a donor and subsequently, the recipient’s immune system must not trigger a rejection.

Kidneys, livers, hearts, and bone marrow are among the most commonly transplanted organs and tissues. While some organs (such as the heart) can only be donated when the donor has died, others (such as the kidney, liver and bone marrow) can be donated by living donors.

Worldwide, the figures speak for themselves. Every day, hundreds of thousands of people continue to wait for an organ; thousands die while waiting for the arrival of an organ they need to survive. A single person can potentially save up to eight lives, since one person can donate eight organs. Approximately 10% of potential recipients die while waiting to receive an organ.

Transplant rejection: why does it happen?

Each of us has an individualised immune system, which is affected both by our genetics and our environment. This system recognises foreign bodies and infectious agents, helping to protect us against disease. Agents from outside the body may be infectious (such as bacteria or viruses), but so can cells that come from another person whose immune system and own individualised response are very different from ours.

Nucleated cells have markers on their surface that are recognised as foreign once they are inoculated or transplanted to another subject. These markers are called histocompatibility antigens (Ag) or transplantation antigens and they provide the tissues of every individual with unique characteristics that differentiate them from others.

Our “innate immunity” does an excellent job in protecting us and is characterised by:

  • a rapid response in its first line of defence (such as the skin, our largest organ) against infectious agents
  • its ability to stimulate non-specific immune cells that work to destroy potentially harmful substances that have entered the body

When the intrusion is so severe that the innate immune system can no longer cope, our “adaptive immunity” comes into play. Adaptive immunity is characterised by a more specific, slower, and longer-term response provided by specialised cells (such as T cells and B cells) against agents from outside the body. This is the kind of immunity that comes into play with transplant rejection.

Although organs and tissue transplants currently help to prolong peoples’ lives more than ever before, there are risks involved. There are several types of rejection. One of the main problems is when the recipient’s immune system (specifically, their T cells) recognises the new organ or tissue donor as “foreign” and begins to attack and destroy it.

For this reason, it’s essential that the recipient’s immune system is as similar as possible to the donor’s, which can be very difficult to coordinate given how unique everyone’s immune system is, and the speed with which organ failure can lead to death.

And this is where THC comes in.

The immune system: can rejection be avoided?

To avoid rejection, the tissue must be examined prior to transplantation in order to identify whether or not the antigens it contains are compatible with the recipient. Although tissue examination ensures the transplanted organ or tissue is as similar as possible to the recipient’s, there’s no such thing as 100% compatibility.

No one has antigens that are identical to those of someone else, except in the case of identical twins. For this reason, it’s necessary to use immunosuppressive drugs (which suppress our immune system) so the body doesn’t always trigger an immune response thus causing destruction of the foreign tissue.

About 25% of kidney recipients and 40% of heart recipients experience an episode of acute rejection during the first year following transplantation. Luckily, rejection episodes don’t necessarily mean the loss of the organ.

However, although more than 90% of acute rejections can be treated successfully with modern immunosuppression treatment, it’s important to note that the immunosuppressive drugs currently available to prevent transplant rejection can have harmful side effects themselves. These side effects can include:

  • Diarrhoea
  • Hypertension
  • Acne
  • Weight gain
  • High cholesterol
  • High levels of blood sugar
  • Susceptibility to infection
  • Dental problems

Taking all these factors into consideration, in addition to the fact that demand for organs is far greater than the available supply and that the majority of patients often only have one chance with a donor organ or tissue, transplant rejection can have devastating consequences, which can lead to death.

Organ transplant rejection: can THC help prevent it?

To conduct the study in question, Nagarkatti used mice that had undergone skin transplant surgery, transplanting the skin of a group of mice to another group of genetically different mice. The incompatible skin was treated with either a placebo or THC, the active cannabis compound.

By injecting donor spleen and skin cells in recipient mice (thus using rodents as models for humans undergoing organ transplant), the researchers found that the recipient mice treated with THC were less likely to reject the new tissue than those that were treated with the placebo. The study showed that by activating CB1 receptors, THC helped prevent rejection through several mechanisms:

  • Preventing an increase in the number of T cell receptors in the recipients’ lymph nodes, thereby reducing the likelihood of a rejection of the donor tissue
  • Effecting a decrease in inflammatory response signals
  • Stimulating myeloid suppressor cells, which act to decrease the response of the T cell receptor and prevent rejection
  • Increasing the duration of the survival of skin cells from donors

It’s worth remembering a previous study published in 2013 in the online magazine Journal of Pharmacology Neuroimmune. This study anticipated how THC could stop the immune reaction that causes the transplanted organs to be rejected, in this case through the CB2 receptors.

Although this study only used cell culture models, the researchers observed a dose-dependent effect: higher doses of THC led to higher levels of immunosuppression. In addition, two synthetic cannabinoids were also included, and it was found that they could work just as well.

Based on these results, the researchers concluded that cannabinoids are promising in terms of improving the success rate of organ transplants.

Study results: THC as a treatment for transplant rejection

This study by the University of South Carolina joins the growing body of evidence that shows that cannabinoids are useful in modulating and reducing inflammatory processes that are involved not only in transplant rejection, but also in autoimmune disorders, cancer, and many other serious debilitating diseases.

“Altogether, our research has shown that for the first time, in our understanding, cannabinoid receptors can provide a new method of treatment for graft versus host disease (GVHD) and prevent allograft rejection through the suppression of the immune response in the recipient,” the research team concluded.

Given the serious side effects associated with current treatments used to prevent transplant rejection, along with the very favourable safety profile of THC, the authors say that more effective treatments with fewer side effects are desperately needed. Unfortunately, advances in cannabis-based medicine appear to be driven by the development of synthetic compounds instead of pure scientific discovery.

“These data support the potential of this class of compounds as useful therapies for prolonging graft survival in transplant patients,” said Mitzi Nagarkatti.

Medicinal cannabis patients awaiting transplant are adversely affected

It seems incredible and paradoxical that although the THC content of medicinal cannabis can help transplant patients in many countries, patients who use medicinal cannabis may be denied an organ transplant. Yes, those who use cannabis to treat a large number of diseases (or relieve their symptoms) and test positive for cannabis may be denied. This is particularly ironic when it occurs in the United States, where medicinal cannabis is legal in many states.

However, various cases have been publicised by the media, such as that of a 64-year old patient named Norman Smith. He was informed his doctors would take him off the list of transplant patients unless he stopped consuming cannabis for at least six months.

They also required him to take part in a treatment program for substance abuse in this period. The irony is that, in that same medical centre, Smith had been given a prescription for medicinal cannabis to help him cope with the adverse effects of chemotherapy treatment for his liver cancer. Unfortunately, Mr. Smith died before being reinstated on the waiting list for a transplant.

Dr Colquhoun argued that they “must consider issues of substance abuse seriously since it does often play a role in the evolution of diseases that may require transplantation, and may adversely impact a new organ after a transplant”. Again, it’s ironic that this statement is not based on scientific evidence, given that cannabis use does not cause organ malfunction or failure.

Moreover, equating the use of a medicinal herb for pain relief in terminal disease with a substance abuse problem seems to be an error in judgment on the part of a healthcare professional. These statements appear to be based on stigma and ignorance.

Unfortunately, such decisions may have fatal effects on the lives of innocent people; people who are ill and require a transplant just as much as other patients in the same situation. Especially since a 2009 study found that cannabis users and non-users had similar survival rates after a liver transplant and that “Current substance abuse policies do not seen [sic] to systematically expose marijuana users to additional risk of mortality.”

Today, there are eight U.S. states that make it illegal to deny an organ transplant based on the use of cannabis. However, this is trickier than it sounds. The fight in Oregon to not discriminate against cannabis users is ongoing. But as Piseth Pich, community relations official for Legacy Health, told AP News: “That being said, it’s difficult to identify a specific number of patients who may be considered less for a transplant based on one factor alone”.

Undoubtedly, there’s a need for a change in existing policies that deny access to healthcare for these people, so that cannabis is recognised as a legitimate medicine. Policy makers would do well to take a page out of California’s book, where a law has been passed to protect such patients.

Proving that THC can help reduce transplant rejection

There’s a clear need for further and more in-depth research into the usefulness of THC in preventing the rejection process in humans. It’s disheartening that it hasn’t already been done, seeing as how THC’s usefulness in preventing transplant rejection has been a topic of discussion as far back as 1974.

The potential of THC in this field should be explored in order to prolong and save many more lives worldwide – lives that are given a second chance thanks to altruistic donations made by thousands of caring people. Lives which, thanks to THC, could overcome the awful prospect of rejection after receiving a much-needed transplant.

  • Disclaimer:
    This article is not a substitute for professional medical advice, diagnosis, or treatment. Always consult with your doctor or other licensed medical professional. Do not delay seeking medical advice or disregard medical advice due to something you have read on this website.


30 thoughts on “Can THC Help Prevent Transplant Rejection?”

  1. I had a liver transplant 3 and 1/2 years ago, I’m feeling well at the moment and all my labs results are good. I’m taking the normal anti rejection medicine – Prograf and Mychophenolate – but those drugs have a very bad side effects on my body.
    I came through this research a few months ago. My question is there are any trials with THC or CBD in US ? If yes I really appreciate have the information in order to pursue it. I leave in state of Virginia and I don’t have a clue where I could have access of this too and if there doctors in Hampton Roads area that can help with this matter.
    I really appreciate have someone reply to my message .



    1. Scarlet Palmer - Sensi Seeds

      Hello Ray,

      Thanks for your comment. Unfortunately I don’t know whether there are any trials in the US, but I suggest you get in touch with a local medicinal cannabis group (most states have at least one) as they may be able to provide you with information. A good start might be the Hampton Roads branch of NORML (just google ‘Hampton Roads NORML’ and you will find their contact details). If you do approach your doctor about it, this article about the use of cannabinoids in medicine for medical professionals may be helpful. Sorry I can’t be of more help, and good luck!

      With best wishes,


    2. Stewart Stephenson


      I had liver TX in 1997 at Mayo Rochester. Was using cannabis at the time of transplant(apparently it wasn’t a death sentence to transplant candidates then) and I have used every day three times a day for the last 19 years. I am healthy as a horse and drive my transplant coordinators absolutely batty…I relish telling them how idiotic their position is and jump at the chance to discuss the “morality” of the situation when they dare mention the word moral in our current discussions.
      I was diagnosed with Secondary Sclerosising Cholangitis in Febuary of 1998 and they DEMANDED that I cease cannabis use and alternatively start Xanax, Lamotrigine, and Zoloft. That experience nearly cost me my life; it certainly cost me my career and most of my friends. When I told the Mayo to pound sand and I went back to daily cannabis use, my life normalized again.
      Ray, smoke up, vape, edibles, whatever you like….don’t worry: I’ve done 19 years of research for you-your welcome!

      1. Hi Stewart, sorry reply only today. But I changed my phone and lost this link.
        Thank you so much for your comments and input. I leave in Virginia and here I cannot get any vaper or edibles. I try talk to my doc but he said he couldn’t help me out. I would love any tip on how can I get any edibles or vape.

      2. I am 24 years in my transplant and on one medication once/day. I also partake in marijuana and many other great herbs!

        Cheers to being alive and well!

  2. I had a cadaveric kidney transplant nine years ago. The first five years I took all the standard ANTI REJECTION PHARMACEUTICALS which gave my tumors and skin cancer. I healed the cancer with cannabis. But more impressive is the fact the last three years, I am immunosuppressive pharmaceutical free. I have been using cannabis THC/ CBD in dosed concentrated form, mixed with coconut oil in capsules. Daily 100mg.
    I have not had any rejection episodes and I am on zero pharmaceuticals.
    I have zero side effects from this cannabis therapy by natural suppression of my immune system.
    My kidney transplant is functioning better today than when I was on all those pharmaceuticals.
    Thanks for sharing, Brian

    1. Hi Brian thank you for your reply. Sorry just saw today the comments. I had to changed the phone and I had lost this link. I am very happy to hear all your comments, but I leave in Virginia and here I cannot get any vaper or edibles. I really appreciate have someone give me a tip on how to get it. To get start on this, the pharmaceutical anti rejection medicine are very hard and very expensive. Any help are very welcome.

    2. Tiffany Tate

      I would love to know how you are doing now ? I am a2x double lung transplant recipient . I also just go diagnosed with esophageal cancer . I am working on my medical card as we speak and want to know if I can take the weed with my antisupressant meds. Any help would be great
      Thanks tiff

    3. actually had a doctor that let you get off of your anti rejection meds to use cannabis?

      I see your post was from 2016. How are you doing these days?

    4. Christina K

      Wow…that is AMAZING! I had a liver transplant in 2005 and I am on two anti-rejection meds. I am sitting here looking at a bottle of full spectrum CBD wondering if it would harm me to take. I ordered it due to pain everywhere in my joints. I want to take it, and I am waiting right now for my transplant doctors to let me know if it would be alright to take these… But, knowing at the same time that they will most likely tell me no way to cover their behind. What I am reading on here today is so promising to me though today.

    5. Kevin Hopf, I too am free of anti rejection meds for 16 years. But I use no cannabis

      I am on Facebook if anyone wants to know what I did to stop using pharmaceuticals

      1. Curt duboise

        Re: kevin kopf,,,I would like to know how you are preventing rejection.

  3. I had a kidney pancreas transplant and am losing weight and not gaining it back . My wife who dont and has never smoked has no clue . I am a smoker of 25 yrs will smoking damage anything or react bad with the rejection meds i never miss taking them. Can someone help that has more knowledge its been 2 weeks so far and ive lost 25 lbs

    1. Scarlet Palmer - Sensi Seeds

      Dear Joey,

      Thank you for your comment. We are sorry to hear about your situation. Unfortunately, as Sensi Seeds is not a medical practice, we are not able to provide any advice relating to medical situations other than to consult your doctor or other licensed medical professional. This article, written specifically for healthcare providers who may not be aware of the many properties of cannabis, may be useful to you in talking with your doctor. You could also try to contact local medicinal cannabis support groups, if you have not already done so. In the UK, there is the United Patients Alliance (you can find them on Facebook) and in the US and EU there are many branches of NORML (google NORML followed by your area name). We hope this is helpful.

      With best wishes,


  4. I would absolutely love to know more about this! I’m 20 months post double lung transplant and take Pharmaceuticals to suppress my immune system along with many other drugs. I do on occasion partake in edibles. And if this would help more with rejection that would be wonderful!

  5. Steven Buonomo

    I am 10 yrs post liver tx. I fight with my drs to get off the immunosupressants and they insist that i must take them. I have weened down to 25mg cyclosporine 2x daily and cellcept 250mg 2x daily. But I feel like the meds are poison and will kill me . I show” non-detectable” in my cyclosporine level blood test(whats the point in taking it then RIGHT). I want to ween myself off the meds while using CBD oil and smoking some weed. What are thoughts on my plan?

    1. Scarlet Palmer - Sensi Seeds

      Dear Steven,

      Thank you for your comment. We are sorry to hear about your situation. Unfortunately, as Sensi Seeds is not a medical practice, we are not able to provide any advice relating to medical situations other than to consult your doctor or other licensed medical professional. This article, written specifically for healthcare providers who may not be aware of the many properties of cannabis, may be useful to you in talking with your doctor. You could also try to contact local medicinal cannabis support groups, if you have not already done so. In the UK, there is the United Patients Alliance (you can find them on Facebook) and in the US and EU there are many branches of NORML (google NORML followed by your area name). We hope this is helpful.

      With best wishes,


  6. I had A Single Lung transplant 10 months ago, I take CBD oil as well as edibles to get the THC
    As for me my labs are normal and have had my drugs reduced by more than half, it’s those meds that cause me problems not the CBD or THC
    I have had no sign of rejection or any complications
    I wish there was somewhere I could provide my test data to a study, that way at least it would track my progress compared to those who only take the drugs. I had bladder cancer in 2005 so seeing that the oil has been proven to cause cancer cells to die, is important to me since cancer is a very valid concern for those on rejection drugs, so if this helps prevent a reoccurrence I’m going to continue my use. I get blood work every Monday and it has remained stable to this point.
    I feel great, the oil even reduced the ringing of my ears, if any other lung transplant folks are taking CBD/THC please let me know your results

    1. David White

      Hi Brad,
      How are things going for you currently? I am a bi-lateral candidate for lung TX and have been following the potential new discoveries and benefits of cannabis in anti rejection therapy. I, like yourself, am not completely confident in current anti rejection medicines and seek input from others and their experience with cannabis in an effort to minimize prescribed dosing levels of anti rejection medicines.
      Thank you.

  7. David White

    Hi Brad,
    How are things going for you currently? I am a bi-lateral candidate for lung TX and have been following the potential new discoveries and benefits of cannabis in anti rejection therapy. I, like yourself, am not completely confident in current anti rejection medicines and seek input from others and their experience with cannabis in an effort to minimize prescribed dosing levels of anti rejection medicines.
    Thank you.

    1. Scarlet Palmer - Sensi Seeds

      Hi Bill,

      Many of the studies mentioned are linked to from within the article (the text in green), or can be found using google. However, for some it is necessary to pay in order to download and read the entire article, although you could try contacting the authors directly and asking them for a copy. Good luck!

      With best wishes,


  8. Arnold R Bunty

    Hello, I am a 66 year old man, received kidney transplant Oct. 1, 2001, I also had Crohn’s disease, which I put in complete remission with RSO (Rick Simpson Oil) been 2 1/2 years since I had any symptoms, I am taking (oil) with Immune suppressants, Cellcept, and 3mg Prograf daily, I haven’t noticed anything, from what I see, my health has improved so much since I started taking the oil! It controls my weight, cured my acid reflux, controlling my Blood Pressure, I have eliminated the Crohn’s Disease Meds, the BP Meds, the acid reflux Meds, I read about a compound in Cannabis that lowers your immune system, (still researching) Research Rick Simpson oil, it’s the Best thing I ever did, costing me $100.00 a month! I feel 20 years younger, I am convinced this is a Miracle Cure for many ailments!

  9. Post liver transplant here, this article would go great in conjunction with one regarding the DANGERS of CBD in concomitant use with immunosupressants, Tacrolimus in particular. They both metabolize on the same cytochrome p450 3a4 enzyme, thus if CBD is used, it inhibits the enzyme and toxic levels of tacrolimus become released in the blood. Let’s just say, from my personal experience, my 2mg of Prograf BID which currently has me at a safe 6-7 trough value with THC use, was 27-29 (toxic) with CBD. It took approx 4 weeks for my levels to return, the average clearance time for cannabinoids.

    THC – yes post tx
    CBD – no post tx if taking immunosupressants

  10. Does thc affect the heart negatively, even if no heart was transplanted & it is your original heart at birth?

    1. Scarlet Palmer - Sensi Seeds

      Hi Jim,

      Thank you for your comment. As Sensi Seeds is not a medical agency or practitioner, we cannot give any kind of medical advice other than to consult your registered healthcare professional. This article about the potential benefits of cannabinoids might be useful for you to show your healthcare provider if they are not familiar with them.

      You may also find it helpful to contact a support group for medicinal cannabis patients. In the UK there is the United Patients Alliance, and throughout much of the rest of the world there is NORML, who should be able to put you in touch with a group in your area (search United Patients Alliance or NORML followed by your area name).

      With best wishes,


  11. Spot on with this write-up, I honestly believe that this web site needs a great dsal more attention. I’ll probvably be back again to see more, thanks for thee advice!

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