Dosage is Induction: Foscarnet 60 mg / kg IV every 8 hours for 2 to 3 weeks Maintenance: Foscarnet 90 to 120 mg / kg IV once a day Adverse effects of IV foscarnet are significant and include nephrotoxicity, symptomatic hypocalcemia, hypomagnesemia, hyperphosphatemia, hypokalemia, and CNS effects.