Tacrolimus is a common immunosuppression treatment used in pregnancy, typically in women with a solid organ transplant or autoimmune condition. These conditions put women at high risk of pre-eclampsia, however, accurate diagnosis of pre-eclampsia can be difficult to distinguish from tacrolimus toxicity and pre-existing medical comorbidities. Here we present the case of a pregnant women with IgA nephropathy and chronic hypertension, who was admitted at 25 weeks’ gestation with peripheral oedema, worsening hypertension, renal impairment, and thrombocytopaenia, representing a significant diagnostic challenge. The distinction between these conditions can be difficult, but is critical to appropriately target treatment, avoid iatrogenic harm from unnecessary pre-term delivery, and optimise maternal and neonatal outcomes.