Cardiac tamponade due to minoxidil use: a case report and review of the literature

Minoxidil is a direct-acting vasodilator that reduces systemic vascular resistance by opening adenosine triphosphate (ATP)-sensitive potassium channels, leading to arteriolar smooth muscle vasodilation. While commonly prescribed for resistant hypertension and androgenic alopecia, minoxidil is associated with fluid retention, and in rare cases, pericardial effusion that can progress to cardiac tamponade. In this report, we present a case of an 81-year-old male with a history of chronic kidney disease (CKD) who developed cardiac tamponade while on chronic minoxidil therapy for hypertension. He presented with progressive dyspnoea, lower extremity oedema, and fever. Imaging revealed an enlarged cardiac silhouette, and a confirmatory echocardiogram demonstrated a pericardial effusion with right ventricular collapse. The patient underwent urgent pericardiocentesis, yielding 545 ml of pericardial fluid. Infectious, malignant, and autoimmune aetiologies were ruled out, and minoxidil was identified as the likely cause. Following discontinuation of minoxidil, the patient's symptoms completely resolved, with no recurrence at 1-month follow-up. In addition, we reviewed 26 previously reported cases of minoxidil-induced pericardial effusion and/or cardiac tamponade, 17 of which are summarized in this report. This case demonstrates the rare but potentially fatal complication of therapy and emphasizes the importance of early detection and clinical vigilance, particularly in vulnerable populations such as patients with CKD. LEARNING POINTS: This case highlights minoxidil-induced cardiac tamponade - a rare but fatal adverse effect requiring urgent intervention, especially underrecognized in clinical practice.Patients with chronic kidney disease are at increased risk for minoxidil-induced pericardial effusion due to altered fluid regulation and renin-angiotensin-aldosterone system activation.Clinicians should maintain a high index of suspicion and consider routine cardiac monitoring in minoxidil users, even for non-hypertensive indications such as hair loss.