Intravenous : Acute flushing and erythema have been reported; usually occurs within 30-60 minutes and may resolve spontaneously. Serious anaphylactoid reactions have also been reported and are more commonly associated with IV administration, but also occur with oral administration (Mroz, 1997). When used for acetaminophen poisoning, the incidence is reduced when the initial intravenous loading dose is administered over 60 minutes. The acetylcysteine infusion may be interrupted until the treatment of allergic symptoms is initiated; the infusion can then be carefully restarted. Treatment for anaphylactoid reactions should be immediately available. Use caution in patients with asthma or history of bronchospasm as these patients may be at increased risk. Conversely, patients with high acetaminophen levels (>150 mg/L) may be at a reduced risk for anaphylactoid reactions (Pakravan, 2008; )