Hämäläinen 1997c.

Study characteristics
Methods	Randomized, double‐blind, placebo‐controlled, 4‐way cross‐over trial of oral dihydroergotamine
Participants	Children or adolescents < 18 years with a diagnosis of migraine per IHS 1988 criteria and at least 2 migraine attacks per month. Most participants had participated in a previous trial of paracetamol and ibuprofen versus placebo. Randomized (N = 16); 1 medication used (N = 13); analyzed (N = 12)
Interventions	Dihydroergotamine (DHE) mesylate oral solution 2 mg/ml and placebo. Each participant treated 1 migraine attack at home with DHE 20 µg/kg (DHE solution 2 drops/10 kg) and 1 with placebo. If the first dose provided any relief, a second dose could be taken after 1 h. If neither treatment produced an adequate response, 1 further migraine attack was treated with DHE 40 µg/kg and 1 with placebo after contact with the investigator.
Outcomes	Headache relief at 2 h (reduction of severe or moderate pain by at least 2 grades) Pain‐free at 2 h Use of rescue medications Adverse events Other reported outcomes: Patient preference
Headache severity scale	5‐point scale (5 severe, 3‐4 moderate, 2 mild, 1 no pain)
Funding source	Not specified
Publication	Journal
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: no information provided
Allocation concealment (selection bias)	Unclear risk	Comment: no information provided
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Quote: "each patient received two identical bottles" Comment: the taste may have been different between the bottles
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Comment: patients who were excluded were not described
Selective reporting (reporting bias)	Low risk	Comment: all expected outcomes reported