It has been determined that continuing with enrollments in this study is no longer justified due to the lack of significant impact on the expected outcomes.

The purpose of this study is to evaluate the efficacy of clorazepate in addition to the usual medication for treating migraine attack in the emergency room

Each patient will receive the usual migraine treatment: IV ketoprofen 100 mg and, if he suffers nausea and/or vomiting, additional IV metoclopramide 10 mg.

Depending on randomization assignment, patient will receive additional placebo (standard treatment arm) or additional IV Clorazepate 20 mg (study arm). The central pharmacy will be responsible for preparing the medications, using a double-blind protocol.

Inclusion Criteria:

• Age from 18 to 70
• Patient suffering migraine or probable migraine (diagnosis made by neurologist according to IHCD3)
• Present migraine attack lasting ≤ 72 hours
• Headache intensity moderate or severe on the verbal ordinal scale (4 levels: no headache, mild, moderate or severe)
• Patient requiring parenteral treatment
• Affiliation to the French Health-care System "sécurité sociale"

Exclusion Criteria:

• abnormalities of neurological exam, seizure, fever (≥ 38°C), and/or SBP≥180 and/or DBP≥110 mmHg
• suspicion of secondary headache
• inability to understand the consent or scales
• pregnancy or breast-feeding
• known respiratory or liver insufficiency
• acute alcohol consumption or alcoholism
• myasthenia
• Patient requiering treatment with sumatriptan SC, particularly in the event of failure of an anti-inflammatory drug at an effective dose taken within 6 hours
• recent use of benzodiazepines (< 24h diazepam, clonazepam, clorazepate ; < 6h alprazolam, lorazepam, midazolam)
• recent use of pain killers (< 2h)
• contraindication to any of the investigational medication
• contraindication to intravenous access
• previous participation to this study