Cannabis linked to higher transplant rejection and graft failure rates

This study examined how cannabis use affects outcomes in heart transplant recipients, analyzing data from over 2,000 patients (1,054 in each group after matching) treated between 2005 and 2025. Researchers found that while overall survival rates at five years were virtually identical between cannabis users and non-users (17.9% vs. 17.8%), cannabis users experienced significantly higher rates of serious complications. The findings revealed 49% higher rates of transplant-related complications, including 50% more rejection episodes and 62% more graft failure cases among cannabis users.

Beyond rejection rates, cannabis use was associated with additional concerning outcomes: new-onset cardiometabolic side effects were 53% more common and cardiac allograft vasculopathy (a condition where blood vessels in the transplanted heart become diseased) was nearly three times more frequent among cannabis users. Rates of infection and kidney injury were similar between groups. These findings suggest cannabis use may directly interfere with transplant tolerance and long-term graft health, even though it doesn't appear to increase overall mortality in the short term.

The researchers emphasize that this retrospective analysis represents an important warning signal that warrants further investigation through prospective studies. The results may influence future heart transplant evaluation protocols and patient selection criteria, as they suggest cannabis use could meaningfully compromise transplant success despite not increasing death rates. Patients considering heart transplantation should discuss cannabis use history with their transplant team.