Recently, intravenous iron supplements has become increasingly popular because it allows administration of large quantity of iron dosage with simple infusion and is more effective in raising the hemoglobin levels and have less drug-related side effects as compared to oral iron supplementation. Multiple IV formulations of iron are available. However, there have been reports of transient asymptomatic hypophosphatemia with its use. We report here a patient with iron deficiency anemia secondary to menorrhagia, who presented with confusion, disorientation, muscle cramps and severe fatigue 3 weeks following intravenous ferric carboxymaltase from hypophosphatemia.