| Study | Reason for exclusion |
|---|---|
| Chabriat 1993 | Abstract (full data in Chabriat 1994) |
| Diener 2005 | Mixed migraine and tension-type headaches |
| Limmroth 1999 | Intravenous administration - self-administration not possible |
| Nebe 1995 | Mixed migraine and tension-type headaches |
| Tfelt-Hansen 1980 | Not randomised or double-blind |
| Tfelt-Hansen 1984 | Included patients with mild headaches, headaches not IHS classified |
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