Tacrolimus is a common immunosuppressive modality with a range of therapeutic applications, including for rheumatologic disease, nephrotic syndrome, and inflammatory bowel disease. The medication also plays an integral role in organ transplantation. However, tacrolimus has a significant side effect profile, which commonly includes nephrotoxicity, neurotoxicity, infection risk, and anemia. We describe an unusual case of tacrolimus toxicity in a cardiac transplant patient, manifesting as diffuse gastrointestinal ulcerations and pathergy. Our goal was to further characterize the toxicity of tacrolimus to include this rare presentation.