Intravenous immunoglobulin (IVIg) is administered for various indications and generally considered a safe therapy. Most of the adverse effects (AEs) associated with IVIg administration are mild and transient. The immediate AEs include headache, flushing, malaise, chest tightness, fever, chills, myalgia, fatigue, dyspnea, back pain, nausea, vomiting, diarrhea, blood pressure changes, tachycardia, and anaphylactic reactions, especially in IgA-deficient patients. Late AEs are rare and include acute renal failure, thromboembolic events, aseptic meningitis, neutropenia, and autoimmune hemolytic anemia, skin reactions, and rare events of arthritis. Pseudohyponatremia following IVIg is important to be recognized. Renal failure, usually oliguric and transient, occurs mostly on using sucrose-containing products owing to osmotic injury. Among high-risk patients who have a previous renal disease, dehydration, diabetes mellitus, advanced age, hypertension, hyperviscosity, or are treated by other nephrotoxic medications, administration of a non-sucrose-containing IVIg product after accomplishing hydration, in a low concentration and a slow infusion rate while supervising urine output and kidney function, is recommended. Thromboembolic complications occur because of hyperviscosity especially in patients having risk factors including advanced age, previous thromboembolic diseases, being bedridden, diabetes mellitus, hypertension, dyslipidemia, or those receiving high-dose IVIg in a rapid infusion rate. Immediate AEs can be treated by the slowing or temporary discontinuation of the infusion and symptomatic therapy with analgesics, nonsteroidal anti-inflammatory drugs, antihistamines, and glucocorticoids in more severe reactions. Slow infusion rate of low concentration of IVIg products and hydration, especially in high-risk patients, may prevent renal failure, thromboembolic events, and aseptic meningitis.