Adverse effects The main adverse effects of amphotericin B are Nephrotoxicity (most common) Hypokalemia Hypomagnesemia Bone marrow suppression Renal impairment is the major toxic risk of amphotericin B therapy. Serum creatinine and blood urea nitrogen (BUN) should be monitored before treatment and at regular intervals during treatment: several times / week for the first 2 to 3 weeks, then 1 to 4 times / month as clinically indicated.