Inclusion Criteria:  Patient presenting with an acute ischemic stroke (non lacunar) as assessed by cerebral imaging (either CT or MRI), with or without visible vessel occlusion. Patient eligible to intravenous thrombolysis according to current criteria, including patients who will also benefit from endovascular treatment (if eligible). Personal or familial consent to participate in the study.  Exclusion Criteria:  Known hypersensitivity to N-Acetylcysteine or to any excipient from the formulation. Coma and/or NIHSS <4 or ≥20. Daily treatment with Nitrovasodilator before the inclusion. Known asthma or chronic obstructive pulmonary disease requiring bronchodilatators or steroids. Participation to another interventional study if it requires administration of an experimental treatment in the first 3 days after NAC treatment. Women of childbearing age (age < or = to 50) Known history of prior treatment with vitamin-K antagonist or direct oral anticoagulant. Known history of severe hepatopathy including cirrhosis, portal hypertension (esophageal varices) and evolutive hepatopathy.