Anaphylactic reactions may occur when I.V. Acetylcysteine is directly administered at high doses as well as when too fast rate is used. Treatments of those reactions must be symptomatic. Therefore, the product must be administered according to the 'Dosage & Administration' described hereby. Patients suffering from bronchial asthma or with a history of asthma, must be closely controlled since bronchospasm may occur during treatment. In such event the treatment must be immediately suspended. Intravenous administration must be done in a hospital under strict medical surveillance.