What happens when you take cbd with tacrolimus?
Tacrolimus is a calcineurin inhibitor used after solid organ transplant (kidney, liver, heart, lung) and for some autoimmune conditions. It has a notoriously narrow therapeutic window: too low and the graft can be rejected, too high and people develop tremor, high blood pressure, high blood sugar, kidney injury, nerve symptoms, and infections from over-immunosuppression. Cannabidiol (CBD) interferes with the same pathways your body uses to clear tacrolimus, and the result is that tacrolimus levels climb.
- CBD slows tacrolimus breakdown. Tacrolimus is broken down mainly by the CYP3A4 and CYP3A5 enzymes in your gut wall and liver. CBD inhibits these enzymes, so tacrolimus is cleared more slowly and accumulates in the blood.
- CBD blocks a gut transporter. Tacrolimus is also handled by P-glycoprotein, an efflux pump in the gut wall that normally pushes some of the drug back out. CBD inhibits this pump, so more tacrolimus is absorbed.
- Trough levels rise. Because tacrolimus is dosed twice daily and titrated to blood (trough) levels, the combined effect can push levels into the toxic range within days. Conversely, stopping CBD after the tacrolimus dose has been lowered can let levels fall quickly.
This is not a theoretical concern. A case report in the American Journal of Transplantation documented a clinically significant rise in tacrolimus levels when CBD was added, and a controlled Phase I pharmacokinetic trial later confirmed that CBD meaningfully increases tacrolimus exposure.
Why is this important?
In transplant medicine, anything that shifts calcineurin inhibitor levels is treated as a serious safety issue, because the consequences land on either side of a narrow band.
- Tacrolimus toxicity. A large rise in tacrolimus exposure can cause acute kidney injury, disabling tremor, high blood pressure, high blood sugar, and nerve symptoms, sometimes within days.
- Graft rejection risk. If CBD is stopped abruptly after the tacrolimus dose has been reduced around it, levels can drop and risk acute organ rejection.
- Not just high doses. The interaction has been reported with both prescription anti-seizure CBD and lower-dose consumer CBD products, so even over-the-counter oils and gummies warrant caution.
- Disclosure gap. Many people do not think of CBD as a real medication and leave it off intake forms, leaving the transplant team to chase confusing level swings without knowing the cause.
The same caution applies to cyclosporine, sirolimus, and everolimus, which share the CYP3A4 and P-glycoprotein pathways.
What should you do?
For solid organ transplant recipients on tacrolimus, this combination belongs in the critical category. The principle is simple: treat any CBD change like a tacrolimus dose change.
Before any change (starting, stopping, switching brands, or changing how much CBD you use):
- Tell your transplant team first. This includes prescription cannabidiol, over-the-counter CBD oils, tinctures, gummies, vapes, hemp softgels, and high-CBD topicals used over large skin areas.
- Do not start CBD on your own. Let the team plan any anticipatory tacrolimus dose adjustment and schedule a follow-up level check.
Every day, while taking both:
- Take tacrolimus exactly as prescribed and keep your usual dosing times consistent.
- Watch for signs of tacrolimus toxicity: new or worsening tremor, headache, insomnia, tingling in the hands or feet, high blood pressure, reduced urine output, swelling, or new confusion. Contact the transplant clinic promptly if these appear.
After any change:
- Expect a tacrolimus trough level check a few days after starting, escalating, switching, or stopping CBD, as your team directs.
- Do not stop CBD abruptly once tacrolimus has been re-titrated around it; coordinate the taper with your team so levels do not crash.
Review the full plan with your doctor or pharmacist rather than adjusting anything yourself.
Which specific products are affected?
The interaction has been documented for both pharmaceutical cannabidiol (prescription oral solution) and consumer CBD products including tinctures, capsules, gummies, sublingual sprays, and vapes. Full-spectrum hemp oils that also contain THC may add further enzyme inhibition and should be treated as a larger, more variable interaction.
Tacrolimus is sold as Prograf (immediate-release), Astagraf XL and Envarsus XR (extended-release), Hecoria, and various generics. Immediate-release and extended-release forms are equally affected, because the interaction occurs at the level of metabolism and absorption, not the specific formulation.
The closely related immunosuppressants cyclosporine (Neoral, Sandimmune, Gengraf), sirolimus (Rapamune), and everolimus (Zortress, Afinitor) share the same vulnerable pathways and warrant the same caution.
The science behind it
The mechanism and direction of this interaction are well supported by independent evidence:
- So et al., Clinical Pharmacology & Therapeutics (2025; PMID 39601108) — a controlled Phase I pharmacokinetic crossover trial in healthy volunteers confirming that CBD increases tacrolimus exposure. Link
- Leino et al., American Journal of Transplantation (2019;19(10):2944-2948) — a case report documenting evidence of a clinically significant drug-drug interaction between cannabidiol and tacrolimus, with tacrolimus levels rising after CBD was added. Link
- So et al., Clinical and Translational Science (2025) — an in vitro study showing that CBD and its metabolites inhibit tacrolimus metabolism, providing the mechanistic basis for the clinical findings. Link
Together, a real-world case report, a controlled human trial, and an in vitro mechanism study point in the same direction: CBD raises tacrolimus levels, and the effect is clinically meaningful in transplant patients.
Frequently Asked Questions
Can I use CBD if I take tacrolimus after a transplant?
Not without your transplant team's involvement. CBD can raise tacrolimus levels enough to cause toxicity, so any use needs to be planned with monitoring rather than started on your own.
Does this only apply to high-dose prescription CBD?
No. The interaction has been reported with both prescription anti-seizure CBD and lower-dose over-the-counter products. Consumer oils, gummies, and vapes still warrant caution.
Is stopping CBD safer than continuing it?
Stopping is not automatically safe if your tacrolimus dose was lowered while you were on CBD. Stopping abruptly can let levels drop and risk rejection, so any change should be coordinated with your team.
What symptoms should make me call the clinic?
New or worsening tremor, headache, tingling in the hands or feet, high blood pressure, reduced urine output, swelling, or new confusion can signal tacrolimus toxicity. Contact the transplant clinic promptly.
Do CBD topicals count?
High-CBD topicals applied over large skin areas can be absorbed in meaningful amounts, so they should be disclosed and discussed like any other CBD product.
Does this apply to other transplant medicines?
Yes. Cyclosporine, sirolimus, and everolimus share the same CYP3A4 and P-glycoprotein pathways and warrant the same caution with CBD.
Key takeaways
- CBD raises tacrolimus blood levels by inhibiting CYP3A4/3A5 and P-glycoprotein, the pathways that clear it.
- This is a critical interaction for transplant recipients: higher levels risk kidney and nerve toxicity, and stopping CBD abruptly risks rejection.
- The interaction has been reported with both prescription and over-the-counter CBD products, not only high doses.
- Tell your transplant team before starting, stopping, switching, or changing any CBD product, and treat every CBD change like a tacrolimus dose change with a level check.
- The same caution applies to cyclosporine, sirolimus, and everolimus.