Intravenous administration of acetylcysteine, especially in the large doses may result in nausea, vomiting and other gastrointestinal symptoms. Hypersensitivity reactions have been reported following intravenous administration of acetylcysteine. Bronchospasm may occur in conjunction with a generalised anaphylactoid reaction. The symptoms of the anaphylactic-like reaction to acetylcysteine include airway obstruction (bronchospasm), angioedema, dyspnoea, hypotension, shock, tachycardia, urticaria, and injection site reaction (including rash). These reactions occur most commonly either during, or at the end of the period of the loading dose infusion, and may in fact be dose related. Since these anaphylactic-like reactions usually occur following the loading dose, careful monitoring is recommended.